Bi-Monthly Research Notes: Vol 13, No 1-6

DEPARTMENT OF AGRICULTURE
SCIENCE SERVICE-FOREST BIOLOGY DIVISION
Vol. 13
REPORT
Number 1
BI-MONTHLY PROGRESS REPORT
Jan: Feb.
1957
Published by Authority of the Right Hon. James G. Gardiner, Minister of Agriculture, Ottawa
CURRENT ACTIVITIES
ATLANTIC PROVINCES
Virus Symptoms Associated with Birch Dieback. —During the past two years the possibility that dieback of white
and yellow birch, Betula papyrifera Marsh. and Betula lutea
Michx. f., is a virus disease has been studied. In 1955 and
1956 selected diseased and healthy yellow birch trees in
New Brunswick and in Nova Scotia were examined frequently during both the growing and the dormant seasons
to secure more information on the symptoms. Several
complicating factors were encountered. It was not always
possible to distinguish clearly between symptoms associated
with the unknown primary cause of the disease, symptoms
associated with unknown minor maladies, and symptoms
associated with secondary invaders, such as the bronze
birch borer, Agrilus anxius Gory. Some of the most striking
symptoms, such as ring spot, that appeared on typically
diseased trees only, were not persistent. On the other hand,
a number of symptoms that have often been associated
with virus diseases, such as leaf roll and tatter leaf, were
found as frequently on trees considered free of dieback as
on typically diseased trees. For these reasons, the description of the symptoms of birch dieback that follows must
be considered tentative.
The most conspicuous symptom of the malady on yellow
birch was an atypical growth habit. In the spring many
of the buds on the previous year's growth failed to develop
or produced distorted shoots that withered away very early
in the growing season. A continuation of this process
resulted in the death of twigs and branches. With further
development of the disease the foliage was often clumped
near the ends of branches due to, (a) the failure of many
of the spur buds farther back on the branches to produce
leaves, (b) leaf development from proliferated bud masses,
(e) a tendency of the leaves to be rolled and pendant, or
more rarely, (d) rosetting. As dieback of the shoots progressed some of the lateral spur buds farther back on the
affected branches produced willowy, upright shoots. As the
tips of this new growth died back, buds farther back on
the same stem produced more upright shoots, which sometimes resulted in the development of witches' brooms throughout the crown of the tree. Over a period of several years
the larger branches died back to the boles. This stage
in the development of the disease was generally characterized by the production of a large number of adventitious
shoots on the main stem and by severe borer attack,
followed by death of the tree or occasionally apparent
recovery. The mortality within the crowns of affected trees
was accompanied by a high mortality of rootlets and a
marked reduction in radial increment.
Many parts were affected by the disease, the buds,
the aments, the leaves, and the twigs all exhibiting symptoms.
The mature buds were swollen and yellowish rather than
reddish-brown. The sterile aments also were yellowish
rather than reddish-brown and at maturity frequently failed
to attain normal elongation. Pollen cells from diseased trees
were often plasmolysed and irregular in size. The fertile
aments were frequently somewhat shrivelled when immature
and at maturity were variable both in shape and in size
with reflexed bracts. The seeds generally were rounded
rather than spindle-shaped, and were often sterile. The
leaves on diseased trees were exceedingly variable. In some
cases, particularly in the upper crown, they were small,
cupped, and yellowish. These fell from the trees prematurely and the following season only a few scattered leaves
replaced them. The remaining leaves in the crown were
abnormally thick, distinctly waxy, off-colour, and often
cupped. From time to time many non-persistent symptoms
including crinkle, mild mosaic, vein clearing, a conspicuous
ring spot, and leaf roll were present on the leaves. There
was much variation in the size of leaves on diseased trees.
Spur leaves near dying tips sometimes were abnormally
large; sometimes the leaves were of normal size; and sometimes, particularly in the periphery of the crown, they were
very small, irregularly shaped, and generally distorted. Small
71521
necrotic lesions were frequently found on the midveins and
petioles of the leaves. Small, black lesions with sharply
defined margins often occurred on the smaller branches and
twigs. These lesions gradually enlarged to girdle the stems
and resulted in the production of small, cupped, yellow
leaves distally, and a relatively sudden dieback of shoots.
Since many of these symptoms seemed to be typical of
virus diseases, a wide variety of transmission trials were set
out in growth chambers, in greenhouses, in nurseries, and
in the field. Several methods were employed. To test
seed transmissibility, seedlings were grown from the seed
of both healthy and diseased white and yellow birch. Eventually, these seedlings will be tested as sources of inocula.
In separate experiments, imported, 4-year-old, previously
healthy, yellow birch seedlings, and in some cases also white
birch seedlings, received scions from either healthy or diseased trees and were grown in the growth chambers, in_
the greenhouse, or in the nursery. Some of the healthy
seedlings were approach-grafted, either by roots or by
stems to typically diseased trees in the field. Many of the,
seedlings that received scions from diseased trees showed
striking symptoms during the second growing season following the grafting. Symptoms of these seedlings resembled
those found in the periphery of the crowns of typical dieback trees. The checks remained healthy. All the seedlings that were approach-grafted by stems to dieback trees
became diseased during the same season the grafts were
made. Eight weeks after grafting the seedlings were removed
by excising the branches of the mature trees immediately
below the approach-grafts. The seedlings with the shoots
of the originally diseased trees now grafted onto them were
set out in the nursery. During the following growing season,
typical dieback foliage was produced on the scions and the
seedlings had some of the symptoms of birch dieback,
Conclusive results have not been obtained yet with seedlings that were approach-grafted to roots of dieback trees.
In the nursery an attempt was made to secure transmission
of the disease with leaf hoppers. This experiment and a wide
variety of trials designed to test mechanical transmissibility
were inconclusive.
In a series of field experiments, apparently healthy 40to 60-year-old yellow birch trees received scions or pollen
from diseased and healthy trees. Whip, cleft, a variety of
side grafts, and bark patch grafts were applied. The attempt
to transmit the disease with pollen from diseased trees
failed. Conclusive results have not yet been obtained where
the top grafts were applied, but ten out of twelve of the
trees that received bark patches from diseased trees exhibited
definite symptoms the second season after the attempted
inoculations. These were suggestive of the early symptoms
of birch dieback. A corresponding number of check trees
remained healthy. Thus, although many of the transmission
trials have failed or have not yet yielded conclusive information, the results to date have shown promise. An infectious
agent has been transmitted from typical dieback trees with
virus-like symptoms to previously healthy seedlings and
mature trees. It is not yet known whether the disease that
has been transmitted will prove sufficiently severe to account
for the recent and continuing wide-spread mortality of
white and yellow birch in Eastern Canada and in the
Northeastern United States.—J. G. Berbee.
QUEBEC
Spruce Budworm Development in the Gaspe Peninsula
in 1956.—In 1956 budworm emergence began somewhat
later than in 1955, about May 27 at the lower elevations,
and about June 8 in the Shickshock Mountains and in the
eastern part of the Gaspe Peninsula. In 1955 the difference
in development for the various regions became less apparent
as the summer progressed, and, almost everywhere in the
Peninsula, close to 50 per cent of the population had reached
the adult stage by mid-July. In 1956 development at lower
elevations was two weeks behind that of 1955 throughout
the summer. At higher elevations, development was even
more retarded; by mid-July there were as yet no pupae,
Collecting Wood-boring Beetle Adults by Turpentine
and Smoke.—Current long-term studies of the immature
stages and life histories of cerambycid beetles at Laniel,
Que. necessitate collecting large numbers of adults for
rearing stocks. Collecting live specimens of other than
flower-visiting species by the usual methods is time-consuming
and often unsuccessful from the standpoint of numbers
taken. In 1956, an attempt was made to attract adults to
baits. Fermenting solutions of molasses and of honey were
tried, with only mild success. Previous observations of
insects congregating around fresh paint, and of high borer
populations in forest fire areas, suggested the use of turpentine and smoke, and when these materials were used highly
satisfactory results were obtained.
Turpentine was placed in a shallow, screen-covered metal
pan on a stand 4 feet from the ground. Beetles were
observed to alight from 2 to 10 feet away rather than
immediately around the pan, and collecting was therefore
facilitated by placing the bait near a landing surface such
as a wall or a tree trunk. Most success was obtained during
the latter half of June on warm, humid days with a light
wind, and particularly in the late afternoon. On good days,
results came swiftly when the bait was set out, and within
minutes scores of insects would appear that had not been
present in the immediate area before.
The following cerambycids, all of which infest dead or
dying conifers, were taken at turpentine baits (the species
are listed in descending order of numerical occurrence) :
Asemum atrum Esch., Acmaeops proteus (Kby.), Rhagium
inquisitor (L.), Evodinus monticola (Rand.), Tetropium cinnamopterum Kby., Monochamus scutellatus (Say), Sachalinobia rufipennis (Swaine and Hopping), Xylotrechus
undulatus (Say), Pogonocherus mixtus Hald., Phymatodes
dimidiatus (Kby.,). Among the other Coleoptera attracted,
the following, which also infest conifers, have been identified:
Cleridae, Thanasimus dubius (F.) ; Scolytidae, Dendroctonus
valens Lee., Ips pini Say, Hylurgops pinifex Fitch, Polygraphus rufipennis Kby.; Curculionidae, Pissodes affinis
Rand., Hylobius congener D.T. Large numbers of a
rhagionid fly, Rhagio sp., also congregated around the bait.
In employing smoke as a bait, a small fire of resinfilled red pine chips was made in a metal pail, and fed with
black spruce gum and coniferous foliage. Results were best
in the late afternoon when there was a light, steady wind.
Four species of cerambycids were attracted in large numbers:
in June and July, T. cinnamopterum, A. proteus, and A.
atrum; and, in September, Anoplodera canadensis (Oliv.).
It is of interest that T. cinnamopterum was attracted in
much larger numbers by the smoke than by the turpentine.
The bark beetle D. valons was also strongly attracted by
the smoke.
There could be no doubt about the attractiveness of the
smoke. Insects were repeatedly observed to fly in directly
along the smoke, pass the "smoke generator", and alight
on the first convenient surface. Although no estimate was
made of the distance the smoke exerted its attraction, beetles
were seen many times to fly in on surprisingly direct paths
from as far away as the eye could pick them up, a distance
of about 75 feet. This reaction to smoke appears to explain
the huge populations of wood-boring insects found in forest
areas devastated by fire.
It is interesting that collecting by the above methods
ONTARIO
was highly successful in an area at least a mile from any
recent cutting, and where there had been no fire or windIt is regretted that the following table was inadvertently
throw to provide breeding sites for large borer populations.—
omitted from the text of Mr. Erik Jorgensen's contribution
L. M. Gardiner.
entitled "Note on the distribution of Fomes annosus (Fr.)
Cke. in Plantations in Ontario" which appeared in the last
PRAIRIE PROVINCES
issue of the Bi-Monthly Progress Report.
TABLE I
Jack-pine Budworm in Pine Plantations in the Spruce
HOST INDEX AND KNOWN DISTRIBUTION OF FOmes annosus IN ONTARIO
Woods Forest Reserve, Manitoba, in 1956.—The Spruce
Locality
Woods Forest Reserve in south-central Manitoba covers an
Host
area of approximately 200 square miles consisting largely
Midhurst
St. Wi lliams
Vivian
Forest Nursery
Forest
Forest Nursery
of grass-covered sand dunes formed on the site of a glacial
delta. White spruce, Picea glauca (Moench) Vasa, occurs
Juniperus Plt.
in scattered clumps throughout the area. The only other
virginiana Nat.
naturally occurring coniferous tree species are black spruce
Rep.
and tamarack, which are confined to swampy sites. During
Plt.
Pinus the period 1904-1929, a nnumber of plantings of jack pine,
Nat.
banksiana
Rep.
X
lodgepole pine, and Scots pine were undertaken, and their
Plt.
Pinus establishment has met with varying success (Jameson, Dept.
Nat.
resinosa
Northern Affairs and National Resources, Forest Res. Div.
Rep.
Tech. Note #28, 1956).
x
Plt.
Pinus The presence of the spruce budworm, Choristoneura
Nat.
sylvestris
fumiferana (Clem.), in this area has been known for two
x
x
Rep.
decades. Native white spruce has periodically suffered severe
Finns Plt.
defoliation but no significant tree mortality has resulted.
strobus
Nat.
Rep.
X
The jack-pine budworm, Choristoneura pinus Free., was first
Picea Plt.
recorded in the Reserve, by the Forest Insect Survey, in
Nat.
glauca
1954 and the first evidence of severe defoliation by this insect
x
Rep.
was noted in 1956. Defoliation surveys were conducted in 59
plantations; of these, 43 showed some degree of defoliation.
Plt.—Planted Nursery Stock.
Nat. Rep.—Natural Reproduction
and by the end of August 50 per cent of the pupae were
still unemerged.
Oviposition occurred mostly in September, over a period
of several weeks. Although the days were relatively warm
and sunny in September and October, the nights were generally cold and frosts were frequent. The average maximum
and minimum temperatures at Berry Mountain Depot (elevation 1000 feet) was 60° and 34°F. for September, and 55°
and 29°F. for October.
During early November branch samples were obtained
from balsam fir trees from eight different localities varying in
altitude between 1,800 and 2,500 feet in the vicinity of St. Anne
Lake, Madeleine Lake, and Brandy Brook. These branches
were examined for pupae and egg-clusters. Thirteen per cent
of the pupae were unemerged, and when 63 of these were
kept at room temperature, two Phaeogenes hariolus (Cress.)
and three Itoplectis conquisitor (Say) were obtained. These
parasites usually emerged about the end of July, but in
1956 were reared during the second week in August from
pupae collected at lower elevations. After three weeks'
exposure at room temperature the unemerged pupae were
dissected. Fifty per cent contained dead hymenopterous
parasites, the other 50 per cent had died as pupae in varying
degrees of development. The death of at least some of
these parasites and pupae can probably be attributed to the
cold weather.
The egg-mass population was high in all localities and
ranged from 509 to 814 egg-masses per 100 square feet of
branch surface. Of these egg-masses, 53 per cent were
unhatched, 10 per cent partially hatched and only 37 per
cent totally hatched. In two localities as many as 80 per
cent of the eggs were unhatched. The unhatched egg-masses
were apparently healthy, but when 150 of them were kept
at room temperature none produced larvae. The nonviability of these eggs could not be attributed to their not
having been fertilized since embryonic development was
quite advanced in many of them. When the eggs were
counted for 100 clusters, the average number per cluster
was found to be 11.0 ± 0.8. This is somewhat lower than
some previous records obtained in New Brunswick and in
northwestern Ontario where the average number of eggs per
cluster was close to 20.
Although the unusually cool wet summer was largely
responsible for the drastic retardation in the development
of the budworm at high altitudes, it was not the only
factor involved. The year 1956 was a heavy flowering year
for balsam fir throughout Gaspe and consequently shoot
growth was much reduced. Where the insect population
was high, the current year's growth was soon destroyed, and
larvae were forced to feed on old foliage. Approximately
two years' previous growth were destroyed in the region of
the Shickshock Mountains. It has been shown that a diet
of old foliage greatly retards development and reduces
fecundity. The situation that prevailed because of poor
weather was aggravated by a shortage of proper food.
For the reasons given above it is expected that in 1957
the budworm population will be considerably reduced at
elevations above 1,800 feet in the Gaspe Peninsula. This
represents approximately one-tenth of the infested territory.
Elsewhere in the Peninsula, and throughout a large section of
the Lower St. Lawrence, the insect was able to complete its
cycle and heavy populations are again expected in 1957.J. R. Blais.
The prevalence of staminate flowers in all infested plantings
was recorded using the following classification:
Heavy
Trees with the majority of the branches
bearing large numbers of male flowers
Moderate
Trees with a few branches bearing large
numbers of male flowers
Light—nil
Trees with a few scattered male flowers
or none
The following table summarizes the results of these surveys, which were conducted by L. L. McDowall:
RELATIONSHIP BETWEEN DEFOLIATION AND STAMINATE FLOWER PRODUCTION IN
PINE PLANTATIONS INFESTED WITH JACK-PINE BUDWORM
Defoliation of
current foliage
Tree species
Number of Plantations in Various
Flowering Classes
Heavy
Moderate
2
1
3
3
1
Severe jack pine Scots pine lodgepole pine Moderate jack pine Scots pine lodgepole pine 5
6
2
Light jack pine Scots pine lodgepole pine 3
2
Light-nil
7
3
2
All three species of pine were attacked. A marked difference in the degree of defoliation in neighbouring plantations
was evident, and this appeared to be attributable to differences in the prevalence of male flowers. The more severely
defoliated trees were those bearing heavy crops of male
flowers, as is commonly the case in jack-pine budworm
outbreaks.
Due to an unusual combination of factors, the lodgepole
pine plantations suffered the most severe damage. During the
winter of 1955-56, "winter drying" killed most of the foliage
of these trees. Subsequently many of them were heavily
infested with budworm, resulting in the complete destruction
of the new foliage. These trees will probably succumb.
An interesting biological sidelight of the current outbreak was a breakdown in the usual temporal isolation of the
two budworm species (S. G. Smith, Bi-Mon. Progr. Rept.
9 (3) : 2, 1953). This was probably a result of the abnormally
cool weather in May which was followed by a short period
of very high temperatures in early June. These high temperatures stimulated activity in both species.
A small group of early instar larvae, from white spruce,
jack pine, and Scots pine, was collected in mid June and
reared in the laboratory in Winnipeg. The period of adult
emergence for the spruce budworm was as follows:
Males
June 29 to July 5
June 29 to July 4
Females
Emergence of the jack-pine budworm adults occurred as
follows :
Males
July 4 to July 8
Females
July 8 to July 10
Thus the mating and oviposition of the two species overlapped. Smith (loc. cit.) has stated, however, that in the
absence of temporal isolation, reproductive isolation is normally effective in preventing hybridization.—R. J. Heron and
R. M. Prentice.
Notes on Damping-off in the Prairie Nurseries in
1956.—Damping-off incidence was moderate during 1956
in the three forest tree nurseries inspected. Isolations from
diseased seedlings suggested that the main causes were
Pythium spp. Other common isolates suspected of virulent
pathogenicity were Rhizoctonia solani Kühn, and at Indian
Head, Sask., Phytophthora cactorum (Leb. & Cohn) Schroet.
On red pine (Pinus resinosa Ait.) the incidence of P. cactorum
was as high as that of Pythium spp.
Although it is commonly assumed that no damping-off
occurs in new seed-beds established on forest soils, considerable losses occurred in such beds in the Pineland Nursery
in Manitoba. Damping-off was severe in red pine' in scattered
patches on low-lying areas. The beds had been established
in 1956 on a slightly acid site which had been occupied by
aspen. Unusually late sowing and humid weather may have
favoured the disease. In 1955 little damping-off occurred in
similar newly established beds, but isolations showed that
both Pythium spp. and R. solani were present. Two routine
applications of Arasan FX drench at 25 lb./acre given one
week before and three weeks after seeding did not prevent
damping-off.
Many seedlings in the same nursery were damaged by
animals. A part or all of the cotyledons had been * cut away.
These symptoms resembled the common damage by birds,
but may have been caused mainly by chipmunks. A number
of the damaged seedlings succumbed to damping-off. On the
other hand, some seedlings with only a part of the cotyledons
left, later recovered.
In another nursery damping-off of jack pine (P. banksiana Lamb.) was fairly heavy on certain areas. It appeared
that hail damage predisposed the seedlings to damping-off.
The hail occurred at the end of June, and damaged only
seedlings in a tender developmental stage.—O. Vaartaja.
ROCKY MOUNTAIN REGION
Red Stain in Lodgepole Pine.—Red stain is the term
applied to the incipient or early stage of decay in lodgepole
pine. Previously, red stain has generally been attributed to
one principal fungus, Fomes pini (Thore) Lloyd, but recent
investigations in Alberta have shown that at least one other
fungus may predominate.
At Strachan, Nordegg, and Water Valley, a "new"
fungus, Stereum pini (Schleich. ex Fr.) Fr., was isolated from
87% of 148 infections of red stain which were associated with
Basidiomycetes. In the vicinity of Marlborough, 72% of
98 infections of red stain yielded isolates of this "new"
fungus. Other fungi associated less frequently with red stain
were: Fomes pini, Polyporus anceps Pk., Polyporus circinatus
var. dualis Pk., and Stereum sanguinolentum Alb. & Schw. ex
Fr. (Table I).
The firm reddish-brown stage of S. pini in the heartwood
of lodgepole pine has been previously described by Denyer,
1952, Nordin, 1954, and Nordin et al., 1955. Laboratory
inoculations of wood blocks with S. pini have produced red
stain with the subsequent consistent re-isolation of the fungus
from the discoloured blocks. The advanced stage of decay
has not been observed or described in nature, but Nobles
has reported that wood blocks inoculated with S. pini were
discoloured a reddish-brown, and, within a one-year period,
an advanced decay resulted which was described as a "yellow,
fine stringy rot".
This predominance of Stereum pini in pole-size stands
of lodgepole pine is significant because the development of standards for poles and ties exhibiting red stain are
based on experimental results with only the one fungus,
Fomes pini. At present, very little is known about S. pini
and the effect this fungus may have on the quality, strength,
and durability of various forest products such as poles, pulp,
lumber, and ties. Accordingly, data of this nature are urgently
required for S. pini.—V. J. Nordin and E. J. Carmichael.
TABLE I
PERCENTAGE OF INFECTIONS OF IDENTIFIED BASIDIOMYCETES ASSOCIATED WITH
RED STAIN IN LODGEPOLE PINE* IN ALBERTA
Percentage of Infections
Fungus
Strachan, Water-Valley,
and Nordegg**
Marlborough
Stereum pini 87
73
Fomes pini 7
is
Stereum sanguinolentum 3
6
Polyporus anceps 3
Polyporus circinatus
var. dualis 2
Lodgepole pines averaging 85 years old.
** The incidence of fungi is relatively the same in each location.
BRITISH COLUMBIA
Flight Muscle Change During Adult Life in the
Scolytidae.—It was reported recently that in the ambrosia
beetle, Trypodendron, the indirect flight muscles undergo
a marked change during the brood-establishment period
(Nature 177: 1183, 1956). Both before and after broodrearing the flight muscles are large and the beetles fly
readily when tossed into the air. When dug from galleries
containing eggs or larvae, however, the flight muscles are
greatly reduced in size and the beetles do not fly when
tossed. The above report suggested that such a change
would be likely to occur in other scolytids also, because of
the similarity of the pattern of life within this group.
Characteristically scolytids fly briefly when seeking or leaving logs or other plant material but most of their active
life is spent within plant tissue excavating galleries and
establishing brood. Frequently they carry out more than
one attack-brood-production cycle.
During the past season specimens of the following
scolytid genera were dug from galleries and their flight
muscles examined: Dendroctonus (two species), Dolurgus,
Dryocoetes, Gnathotrichus, Hylurgops, Ips (two species),
Phloeosinus, Pseudohylesinus, Scolytus. Most but not all
beetles came from galleries containing eggs. Almost all
individuals, of either sex, had very small flight muscles,
obviously incapable of sustaining flight. A few specimens
with large muscles presumably represented the very early
or very late stage of gallery activity.
The occurrence of reduced flight muscles during the
brood-establishing phase in these genera supports the view
that a temporary flight muscle change, while adults are
active within plant tissue, is a characteristic feature of
scolytid life. Such a change has many implications for the
physiological and ecological study of this important group
of forest insects.—J. A. Chapman.
Aerial Reconnaissance of Beetle -killed Ponderosa
Pine, Aspen Grove Area.—On May 30, 1956, the British
Columbia Forest Service made an aerial reconnaissance of
the timber in the Aspen Grove area to assess the severity
and extent of winter damage during 1955-56. Invited on
the flight were personnel of the Vernon Forest Biology
Laboratory, who were primarily interested in the feasibility
of using aircraft in damage appraisals of beetle-killed
ponderosa pine, especially in areas which contain trees
with winter injury symptoms. The object was to establish
criteria for distinguishing from the air beetle-killed trees
from trees showing winter damage symptoms and to determine the years in which beetle-killed trees were attacked.
Several weeks before the flight a preliminary ground
survey was made on ponderosa pine trees of known years
of beetle attack in the Aspen Grove area to determine
roughly to what degree trees of different years of attack
could be distinguished. At a distance of about 100 yards,
1955-attacked trees could be distinguished from trees attacked
in 1954, though from a greater distance they were indistinguishable and would have to be treated as a single group.
Trees attacked in 1953, 1952, and 1951 were variable in
appearance and would also have to be treated as a group
distinct from the 1955-and 1954-attacked trees. Trees
infested in 1950 and earlier were, as a group, distinguishable
from the preceding groups. Severely winter-damaged trees
could be confused with 1955-attacked trees.
Before the flight, two white canvas sheets 6 feet square,
were pegged on the ground west of Alleyne Lake each
near one of two distinct groups of beetle-killed trees. One
group consisted of 1955-and 1954-attacked trees and the
other contained 1954-and 1953-attacked trees.
The white sheets were readily seeen and the beetle-killed
trees detected from the air at 5,500 feet. At 10 a.m. the
"beetle trees" would have been difficult to distinguish from
neighbouring winter-damaged trees. In spots where winter
injury was light, beetle-killed trees, which usually occurred
in isolated groups, were more easily distinguished.
At about 1 p.m. visibility improved and at 5,500 feet
the groups of "marked" trees could be easily seen as well
EDMOND CLOUTIER, C.M.G., O.A., D.S.P.,
as other beetle-attacked trees. At an altitude of 800-1000
feet the "marked beetle trees" were easily recognized, the
1954-53 trees being more distinct than the 1955-54 trees,
which resembled severely winter-damaged trees.
Aircraft could probably be used to advantage in conducting damage appraisals of beetle-killed ponderosa pine.
Beetle-killed trees seem to occur in distinct groups that
are not difficult to detect at altitudes up to 5,500 feet except
when in the midst of severe winter damage. These groups
are usually so spaced that the speed of the aircraft would
not interfere greatly with tallying the trees. Possibly criteria
could be established to aid in assessing damage by years
(or groups of years) of attack which might be applied to
aerial surveys.
If aerial surveys of beetle-killed ponderosa pine are
contemplated, they should be conducted at the time of year
when most of the trees have recovered from the effects
of winter-injury and flights should be made during periods
of optimum visibility.—S. F. Condrashoff.
RECENT PUBLICATIONS
Carroll, W. J.—History of the hemlock looper, Lambdina
fiscellaria (Guen.) in Newfoundland, and notes on its
biology. Can. Ent. 88 587-599. 1956.
Denyer, W. B. G. and Etheridge, D. E.—A punch card for
decay studies. For. Chron. 32: 429-432. 1956.
Fraser, D. A.—Ecological studies of forest trees at Chalk
River, Ontario, Canada. II Ecological conditions and
radial increment. Ecology 37: 777-789. 1956.
Hedlin, A. F.—Notes on the life history and habits of a
chalcid, Bruchophagus caraganae (Nik.), infesting seeds
of caragana. Can. Ent. 88: 622-625. 1956.
Lyons, L. A.—Insects affecting seed production in red pine,
Part I Conophthorus resinosae Hopk. Can. Ent. 88:
599-608. 1956.
Morris, R. F., Webb, F. E., and Bennett, C. W.—A method of
phenological survey for use in forest insect studies. Can.
J. Zool. 34: 533-540. 1956.
Reeks, W. A. and Smith, C. C.—The satin moth, Stilpnotia
salicis (L.), in the Maritime Provinces and observations
on its control by parasites and spraying. Can. Ent. 88:
565-579. 1956.
Tripp, H. A. and Hedlin, A. F.—An ecological study and
damage appraisal of white spruce cone insecte. Foi.
Chron. 32: 400-410. 1956.
Queen's Printer and Controller of Stationery, Ottawa, 1957.
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DEPARTMENT OF AGRICULTURE
SCIENCE SERVICE-FOREST BIOLOGY DIVISION
Vol. 13
REPORT
Number 2
March-April
1957
BI-MONTHLY PROGRESS REPORT
Published by Authority of the Right Hon. James G. Gardiner, Minister of Agriculture, Ottawa
CURRENT ACTIVITIES
QUEBEC
Hylobius Inju ries as Infection Courts of Root and
Butt Rots in Immature Balsam Fir Stands.-The pathological condition of immature balsam fir stands with related
problems was studied in nine temporary sample plots established in stands of Hylocomium-Oxalis site type in the southwest section of Laurentide Park during the summer of 1956.
Seven sample plots were located in stands originating from
advanced growth after the overstory was clear-cut several
(4-10) years ago and two plots in 36- and 52-year-old stands
of natural origin.
During the course of study, the root systems of 1,926
living trees were examined in order to obtain information on
their pathological condition and on the infection courts of
root and butt rotting fungi. It was found that, on the
average, 26.3 per cent of the trees examined had root systems
which were affected (injured, decaying, or partially dead).
While the percentage is rather low (6.1) in stands up to 10
years old, it increases sharply, as illustrated in Table 1, up
to 67.0 per cent in little more than 10 years.
TABLE I
No. of trees
examined
Age class of stand
Trees with affected root
systems
No.
Per cent
6-10
522
32
6.1
11-15
417
51
12.2
16-20
622
185
29.8
21-25
197
132
67.0
36-40
104
68
65.5
51-55
64
39
61.0
1926
507
Average 26.3
Total The slight decline in the frequency of affected root
systems in stands older than 25 years is probably due to
mortality which becomes rather heavy as the age of the
stand increases, eliminating trees with affected root systems.
The various types of injuries encountered during the
studies and their frequencies by age classes are given in
Table II.
TABLE II
Age class
of stand
No. of trees
examined
Hylobius
injuries
Frequency of
mechanical
injuries
No.
Per
cent
No.
Per
cent
6-10 522
10
1.9
2
0.4
11-15 417
26
6.2
1
0.2
16-20 622
114
18.3
4
21-25 197
36
18.3
36-40 104
28
26.9
51-55 64
23
35.9
Exposed
roots
No.
Per
cent
3
0.7
Unknown
injuries
No.
20
Per
cent
3.8
22
5.3
0.6 74
11.9
3
1.5 99
50.2
0
0 45
43.3
3
4.7 16
25.0
Quite prominent among them, are the injuries caused
by the larvae of Hylobius species which increase in frequency
as the stands become older. The larvae prefer the dominant,
codominant, and intermediate trees of all age classes, although
the suppressed trees are not entirely free from attack.
The larvae bore tunnels under the bark in individual
roots and root-collars, sometimes causing complete girdling.
Although some of the injuries, particularly the smallest, are
soon covered with resin and later overgrown by callus, a
87602
certain proportion remains exposed to infection by various
fungi. The infection may also occur indirectly through the
roots killed by girdling and extensive tunnelling.
Of 237 trees injured by Hylobius, 56.5 per cent were found
to be infected by various fungi, the frequency of infection
increasing with the stand age. To some extent this may be
related to the age and size of wounds.
TABLE III
Age class of stand
6-10 11-15 16-20 21-25 36-40 51-55 Total No. of trees
injured by
Hylobius
Infected injuries
No.
10
26
114
36
28
23
11
63
23
18
18
237
134
Per cent
10.0 42.3 55.2 64.0
63.3
78.2
Advanced decays
No.
Per cent
3
15
4.3
16.7
83.3
Av. 56.5 Total 19 Av.
The first advanced decay which could be associated with
Hylobius injury was observed in the 22-year old stand.
Infections became more numerous (Table III) in older stands,
the majority of them belonging to the white stringy rot type.
Thirty-three different fungi were isolated from injured
roots or root-collars or from advanced decays confined to
roots, root-collars, and butts, which could be linked with
Hylobius injuries. Most frequently obtained in stands of all
ages were several staining fungi which, in a number of
instances, prevented successful isolation of wood-destroying
fungi from advanced decays. Only one wood-destroying
fungus, Stereum sanguinolentum Alb. and Schw. ex Fries, has
been identified so far. The importance of the remaining
fungi is not yet known.
This investigation indicates that a certain proportion of
root and butt rotting fungi, which in a 52-year old stand may
be as high as 60 per cent, enter through injuries caused by
Hylobius larvae.-Edgar Smerlis.
ONTARIO
A New Record of Thrips on Jack Pine in Ontario.A species of thrips, Gnophothrips piniphilus Cwfd., was collected for the first time by the Ontario Forest Insect Survey
in 1956. So far as is known, this constitutes the first record
of this insect in Canada. Preserved specimens were identified
by Miss K. O'Neill and Dr. L. J. Stannard, United States
National Museum, Washington, D.C., in co-operation with
Dr. W. R. Richards, Systematic Entomology and Biological
Control Unit, Ottawa.
The insect caused slight injury to jack pine trees (Pinus
banksiana Lamb.), growing in mixed stands on rocky slopes
in the Temagami Lake area of Ontario. Two partially shaded
trees were found to be heavily infested, the needles of which
were shorter than usual with yellow spots indicating the
feeding sites. The first collection of the thrips was made on
August 14 when nymphs and a few adults were present; a
second collection on August 27 yielded chiefly adults.
The original description of the adult of G. piniphilus was
published by J. C. Crawford in Proc. Ent. Soc. Wash., Vol. 40,
No. 2, 1938. The adults are described as being for the most
part brachypterous, with occasional macropterous forms. This
holds true for the material collected in Ontario. The female
is brownish-black and both forms are about 2mm. in length
when distended. The male is somewhat more brownish than
the female, the brachypterous form being about 1.75 mm. in
length and the macropterous form about 1.32 mm. Nymphs
collected in Ontario were lighter in colour than the adults and
had a reddish tinge.
The species is known to occur in the States of New York
and Rhode Island where Crawford reported severe injury to
nursery stock of Austrian pine. No previous record is known
in North America of G. piniphilus causing injury to native
pines.-O. H. Lindquist and A. A. Harnden.
14.2
PRAIRIE PROVINCES
Damping-off Control by Antibiotic Plant Substances.—
The following experiment was conducted to get preliminary
information regarding various plant materials as agents capable of controlling fungal diseases of tree seedlings.
From a large number of damping-off pathogens, a strain
of Rhizoctonia solani Kuhn was chosen which was highly
virulent on pine seedlings and relatively tolerant to fungicidal
chemicals and various degrees of acidity. This strain was
cultured in glass jars containing 25 cc. of half-strength cornmeal agar. After three days, 50 cc. of mixtures of vermiculite
and various powdered materials of plant origin (see table)
were added on top of the cultures, and moistened. Fifty
seeds of jack pine (Pinus banksiana Lamb) were planted in
each jar. Four jars (control A) contained only vermiculite,
and four jars (control B) vermiculite and 8 mg. of Orthocide
75. This fungicide contains 75 per cent captan (-N-trichloromethylthio)-4-cyclohexene-1,2-dicarboximide. The jars were
kept in the laboratory under fluorescent tubes (General Electric cool white type) which gave a light intensity of 300 ft. c.
After 13 days the following survival of the seedlings was
recorded:
Additive Material
Percentage concentration of
additive material
50
20 5
1
(Number of living seedlings)
1. Leaves of:
P. banksiana 1 (natural site) P. banksiana 2 (prairie plantation) Picea glauca (Moeneh) Voss Abies balsamea (L.) Mill Populus tremuloides Michx Betula papyrifera Marsh Ulmus americana L
Acer negundo L 19
4
25
3
4
9
4
13
32
6
10
8
16
26
24
31
15
17
0
26
22
21
22
7
28
6
0
12
2
0
0
0
36
12
20
32
18
11
22
18
4
9
2
12
P. banksiana P. glauca P. tremuloides o
e
o
o
o
1
o
o
o
o
o
4. Sphagnum
Fresh Sphagnum sp Commercial moss Commercial peat 4
1
6
3
0
1
0
0
0
2
0
0
18
4
0
1
2. Bark of:
P. glauca A. balsamea P. tremuloides 3. Humus and litter of forest stands of:
o
above. The control of Rhizoctonia and other pathogens by
common natural plant substances, as demonstrated above,
may have great ecological importance and may also be
usefully applied in some forest nurseries. Further studies on
this subject appear justified.-0. Vaartaja.
The Susceptibility of Seedlings of Various Tree
Species to Phytophthora cactorum. —Investigations in forest
nurseries in Saskatchewan have suggested that Rhizoctonia
solani Kuhn, Pythium spp., and Phytophthora cactorum (L. &
C.) Schroet. are the most virulent fungi commonly associated
with damping-off of trees. Since there is little or no information available on the pathogenicity of P. cactorum on seedlings of many tree species, the following inoculation
experiment was conducted. An isolate (No. 1341) of P.
cactorum, obtained from diseased Caragana arborescens Lam.,
was cultured on agar in test tubes. Seeds of 13 tree species
were surface sterilized and germinated in petri dishes. Five
germinating seeds of each species were dropped into each of 4
tubes with the fungus and 2 tubes without. The survival of
the seedlings was recorded daily. The technique is reported
in detail in an earlier study which also demonstrated the high
potential pathogenicity of this fungus to seedlings of Pinus
banksiana Lamb. and C. arborescens. (Vaartaja, O. and W. H.
Cram. Damping-off pathogens of conifers and of caragana
in Saskatchewan. Phytopathology 46: 391-397. 1956.)
The cultures were kept in the laboratory under two
different light intensities provided by fluorescent tubes. The
results were as follows:
Av. survival period
Species
Larix sibirica Lebed L. laricina (Du Roi) K. Koch Picea abies (L.) Karst P. glauca (Moench) Voss P. mariana (Mill.) B. S. P P. sitchensis (Bong.) Carr Pinus sylvestris L
P. contorta Dougl. var. latifolia Engelm P. ponderosa Laws P. resinosa Ait Thuja plicata Donn Ulmus americana L Betula papyrifera Marsh 250 ft. c.
80 ft. c.
(days)
(days)
5
64
11
5
7
7
6
4
6.5
6.5
4
7
3
4.5
6.5
5
6
4
6
4.5
23.5
7
8
180+
9
8
5. Lichen
Cladonia alpestre (L.) Rabh 6. Controls
A, Vermiculite, no additive materials
(ay . of 4 replications) B, Vermiculite and Orthocide 75 (ay of 4 replications) 0.2
25.2
Results in the controls, and earlier experience with similar
technique, indicate that this kind of test very sensitively
separates strongly fungicidal materials (including possible
chemotherapeutants) from materials giving poor or no control.
Thus the experiment indicates that materials of groups 1, 2,
and 5 contain fungicidal substances.
Materials originating from Sphagnum are commonly used
to reduce damping-off, but their performance in this test was
poor. The benefit derived from their use in practice may be
indirect, perhaps through the encouragement of common
antagonistic fungi, such as Trichoderma sp. All the materials
from leaves and bark gave some or good control, especially
with the concentration of 20 per cent. Some materials suppressed germination of the seed at higher concentrations;
spruce bark seemed to stimulate germination.
Subsequent weekly survival recordings showed that the
protection by most of the materials gradually decreased, but
less rapidly than that by Orthocide. For instance, after 4
weeks the survival in the spruce bark treatments was still
29, 27, 10, and 2, while it had dropped to 0.2 in the Orthocide
treatment. Lichen was tested also in a garden soil in pots
in the greenhouse. The results were essentially similar to
those above, but in some replications much higher survivals
were recorded.
The control by the various materials was not correlated
with the differences in pH. The very acid materials, such as
peat (pH 4.3 at 50 per cent in 4 weeks), gave poor control,
while alkaline aspen leaves (pH 8.1) gave fair control. Most
of the materials had a nearly neutral reaction. Spruce bark
exhibited the following acidity (in 4 weeks, at the 4 concentrations) : 5.4, 6.0, 7.1, and 7.4.
Water extracts from some of the materials were tested
with distinctly poorer results. This suggests that the antibiotics that caused the disease control either were not readily
soluble in water or were rapidly decomposed in solution. Spruce
bark is used for tanning purposes and may contain large
quantities of antimicrobial tannins. However, no control was
obtained with tannic or gallic acids in a test similar to the
The control seedlings survived for the whole experimental
period of 180 days under 250 ft. c. and for periods varying
from 40 to 180 days under 80 ft. c. The root systems of the
surviving seedlings of T. plicata became visibly diseased in
the tubes containing the fungus while they remained healthy
in the control tubes.
Summary of results: P. cactorum is potentially pathogenic on a number of tree species. T. plicata, and possibly
L. laricina, are less susceptible than most other species. The
disease developed faster on the seedlings which were under
low light intensity.-0. Vaartaja.
ROCKY MOUNTAIN REGION
Red Belt, Atropellis Canker, and Tree Mortality of
Lodgepole Pine in Alberta. —Severe reddening of lodgepole
pine foliage was evident on hilltops near Robb and Lovettville in west-central Alberta during the summer of 1954. This
damage was attributed to climatic causes. The symptoms
were those of the well known red belt disease. The stands in
this region are heavily affected with stem cankers associated
with Atropellis piniphila (Weir) Lohman & Cash. The
effect of red belt on these stands was examined.
One ridge in particular afforded ideal conditions for study
because it supported areas of both green unaffected trees
and moderately to severely reddened trees. Two sample
areas were located within 330 yards of each other on the
top of this ridge where moisture conditions were apparently
similar. Both samples were from stands of about 55 years
of age. Records were made for each area on the percentage
of crown discoloured, the incidence, in 1954, of the canker
caused by Atropellis, and the tree mortality in 1955 and 1956.
Sixty trees from each area were chosen at random from
the collected data using a table of random numbers. The
data are summarized in Table I.
TABLE I
Sample area
Number of trees
with 25% or more
Number of trees
of the crown
dead in 1955
discoloured in 1955
Number of trees
dead in 1956
Area I 22
4
19
Area II 0
2
5
The data on tree mortality were compared, with the
Chi square test revealing a statistically significant difference
(1 per cent level) in tree mortality between area I and
area II in 1956, but there was no statistically significant
difference in tree mortality in 1955. Atropellis canker incidence was similar in both samples with 100 per cent of the
trees cankered.
This evidence indicates that heavy tree mortality may
occur in lodgepole pine stands severely attacked by Atropellis
piniphila after these stands suffer severely from red belt.
This mortality may be delayed at least two years after the
appearance of the climatic damage. Trees severely discoloured in 1954 were green in 1955 but showed thin crowns,
the reddened needles having fallen. There was no red belt
in the region in 1955 or 1956. The probable importance of
delayed tree mortality in stands suffering from other disorders should be stressed in damage appraisals of red belt.
Similarly, susceptibility of Atropellis infected stands to injury
by red belt should be considered in evaluating damage
caused by this canker.—R. J. Bourchier.
New Needle Miner in Banff National Park.—During
sampling for the lodgepole needle miner formerly referred to
as Recurvaria miller?, Busck, a few collections were made of
a needle miner of dissimilar habits. A few collections were
made from 4,080 branches of lodgepole pine. In habits the
larva resembles the miner found by D. K. Campbell at
Squilax, B.C. (Bi-Monthly Progress Report Vol. 7, No. 1,
1951) identified as Recurvaria sp. The larva forms a silken
web about the base of two or three needle bundles and mines
the needles from the base distally. As many as five needles
were partially mined by a single larva during rearing. Larvae
were seen moving from needle to needle within their silken
webs. Unfortunately, none of the rearings were successful
and no observations could be made on the length of the life
cycle. All specimens found were in the larval stage.—R. W.
Stark.
Bruce Spanworm, Operophtera bruceata, (Hulst) in
Alberta.—Two reports of large moth flights of this insect in
the fall of 1956 led to an investigation of its history in
Alberta. Two outbreaks are recorded in the literature, one in
1903 by J. J. de Gryse (Injurious shade tree insects of the
Canadian Prairies. Can. Dept. of Agr., Pamphlet No. 47
N. S. 1925.) and the other in 1913 by F. H. Wolley Dod
(Further notes on Alberta Lepidoptera. Can. Ent. 45: 301,
1913.) who wrote as follows:
"The larvae of this species have again denuded
hundreds of acres of Populus tremuloides in this district
during the present year (1913). The denudation is greater
in extent than it was ten years ago, though none has
been observed during the intervening period. After
starving themselves out on a patch of poplars they spread
to neighbouring species of Salix".
The "district" referred to by Wolley Dod is not defined
but is presumably that around Calgary. Since 1913 this
species has not been sufficiently common to be mentioned in
the literature.
Machine analysis of the material received in 1955 and
1956 revealed that this spanworm was increasing in numbers
in Alberta. The samples from which this information was
taken were made during routine beating of poplar trees by
forest biology rangers and should not be taken as quantitative
samples. The analysis showed that 31 collections containing
approximately 130 insects were received in 1955 and 57 collections containing approximately 530 insects were received in
1956. Although too much emphasis should not be placed
on the actual figures, the rise in population level is obvious.
When the collections were plotted on a map four widely
separated centres of infestation were shown: a small outbreak
of light intensity in the southern end of Kootenay National
Park; an area of light intensity but of considerable extent
covering the aspen belt south of the Red Deer River; a
moderate sized infestation centred around Edson where severe
defoliation occurred at the centre and lessened as it spread
outward; and a small area of light defoliation north of Peace
River. The reports of large moth flights at Calgary and
Edson were from areas where fairly large populations of
larvae were found.
Throughout most of the area the larvae fed on poplar
and willow; in the southern end of Kootenay National Park
they occurred on mountain maple, honeysuckle, alder, and
birch.—C. E. Brown.
BRITISH COLUMBIA
An Induced Differential Bark -beetle Attack.— Provided
that trees are cut during the season when bark beetles are
attacking, most bole inhabiting species will attack conifers
shortly after they are felled. Some aggressive species such as
the Douglas-fir beetle (Dendroctonus pseudo tsugae Hopk.)
which kill healthy or only slightly weakened trees, will often
attack felled trees within a few hours after cutting. In contrast to this, an interesting habit of Trypodendron lineatum
(Oliv.) that has been brought out by earlier studies is that
the initial spring attack of this species is heaviest on trees
that are felled during the preceding autumn and winter,
rather than on spring-felled trees cut one or two months
prior to attack. This attack preference may be due to differences between the chemical composition of winter and spring
sapwood. It is well known that the quantity and quality
of stored food reserves in the sapwood of most trees varies
considerably throughout the year. If this were the only
factor involved, exceptions to the winter-felled preference
would probably be rare. However, a number of outstanding
exceptions have been noted, among them severe attacks on
trees felled in late spring. This leads one to consider environmental factors that may effect chemical changes in the trees
after they have been cut. If temperature or moisture extremes
cause rapid death of the sapwood cells, the resulting chemical
changes may differ considerably from those which take place
in sapwood in which the cells remain alive for a long period
after cutting. It has been shown that heavy Lyctus attacks
occur on winter-felled oak and ash in which stored starch is
retained by killing the sapwood cells rapidly. On the other
hand, these attacks are averted by storing wood under conditions that keep the cells alive long enough to deplete the
starch reserves (Wilson, S. E., Ann. Appl. Biol. 20: 661-90.
1933). The compound effect of variable stored food reserves
and environmental conditions may account for the normal
attack habits, as well as apparently anomalous attacks of
Trypodendron and other scolytids.
In 1955, a small experiment was designed to test some
environmental effects on spring-felled trees. Three western
hemlock and two Douglas fir were felled on April 7 in a
partly opened stand at Cowichan Lake. Two of the hemlock were left uncut, but four 16-inch blocks were sawn
out of each of the other three trees at mid-bole (30 feet
from the butt). These blocks were left in the forest until
April 22, when three of each set of four were removed for
treatment. The fourth of each group was left in place for
control. Three blocks (one from each tree) were weighted
and immersed in the lake, which was 7°C. at the time. The
six other blocks, three of which were wrapped in polyethylene
sheeting, were placed indoors at about 20°C. On May 6 all
blocks were replaced in the field. The first Trypodendron
attacks occurred on May 15. By May 25, all the blocks were
attacked, and attacks were noted at the cut ends of the
remaining tree boles from which the blocks had been cut
out. Counts of ambrosia beetle boring dust piles showed
that most of the attacks had been sustained by June 8.
Moisture content samples were taken on June 15, and the
number of attacks carefully counted at the end of August.
The blocks were de-barked, and 16-inch long samples were
peeled from the remaining boles adjacent to where the short
logs had been removed, and ten feet up and down the boles
from the cut ends. All attack densities were converted to
number of entrances per square foot of sapwood surface.
As shown in the accompanying table, all the 16-inch
blocks were severely attacked, while the remaining boles were
only lightly attacked by Trypodendron. Most of the attacks
on the main boles of the firs were confined to within 1 or 2
feet from the cut ends adjacent to where the short blocks
had been cut out, but the remaining boles of the hemlock
were entirely free of attack. Of the short blocks, the controls were attacked the heaviest; the water immersion and
room temperature treatments reduced the number of entries.
The treatment averages in the table are ranked from greatest
to least attack.
In direct contrast to the Trypodendron attacks, Dendroctonus entries were wanting in the short Douglas fir
blocks, but were abundant along the remaining boles. As
stated previously, this species commonly attacks living or
very "fresh" trees. Therefore, this preference for the long
logs is in keeping with the normal habits of the beetles,
and is further evidence that the short blocks had passed
through a definite stage of decomposition.
Gnathotrichus, an ambrosia beetle that does not show the
same preference for log age groups as Trypodendron, displayed no clear choice between the short blocks and the
remaining boles.
Sapwood moisture content samples taken from the outer
one-half of the sapwood did not show clear differences
between short blocks and long logs. For instance, the short
blocks of the hemlock averaged 99 per cent moisture of
oven dry weight, while the average of three samples taken
from attack-free parts of the long logs was 85 per cent.
Corresponding values for the two firs were the reverse of
this; the short block and bole sample averages were 120
and 130 per cent respectively. More confidence could be
placed in these moisture measures had they been taken
sooner after attack commenced.
The other two hemlock trees that were felled in April
were not attacked during 1955, but in the spring of 1956
both Gnathotrichus and Trypodendron infested these trees.
In the same location, 15 of 20 other fir, felled on December 2,
1954, were attacked by Trypodendron during May 1955.
These data show that Trypodendron attacks were induced
on otherwise unsusceptible spring-felled trees by sawing logs
into short lengths. In the same manner, Dendroctonus
attacks were deterred. The reasons for these differences are
not clear, but it is possible that the sapwood cells in the
short blocks were killed rapidly, thus giving rise to different
decomposition products, than in long logs in which the
storage xylem cells probably remained alive for a relatively
long period.-J. M. Kinghorn.
1
Sample
Description
Treatment Blocks:
Control Immersed Room Temp.
-Wrapped Room Temp.
-Unwrapped Upper Bole:
-End Adjacent to
Blocks -10 Feet Above
Blocks T-Trypodendron
pseudotsugae.
2
Douglas-fir
T
Lower Bole:
-10 Feet Below
Blocks -End Adjacent to
Blocks 3
Average
Hemlock Trypodendron
Attack
Douglas-fir
GD
T
G
D
T
G
Entrance Holes per Square Foot
2.3
5.7
3.8
0.8
4.2
1.0
0.0 1.0
1,0
20.4
2.4
2.8 120.3
4.8
0.3
0.0 0.0
46.9
102.5
86.7
1.1
0.6
0.0 87.0
0.0 77.4
2.0
2.5
0.0 67.0 3.8
0.0 47.0 2.7
85.5
70.4
64.0
2.9
0.0 60.9
4.0
0.0 48.6 2.2
57.8
72.5
1.2
0.0 57.3
0.5
0.0 21.0 0.9
50.3
59.5
1.4
1.8 (No Sample)
22.8
2.9
3.4
lineatum,
0.8
1.8
G -Gnathotrichus
0.3
0.0 0.0
29.8
0.0 0.9
7.9
sp.,
D-Dendroctonus
RECENT PUBLICATIONS
Barter, G. W. Studies of the bronze birch borer, Agrilus
anxius Gory, in New Brunswick. Can. Ent. 89: 12-36.
1957.
Basham, J. T. A technique for the sterilization and inoculation of wood cut from living trees. Can. J. Bot. 35: 31-34.
1957.
Bradley, G. A. Two new species of the genus Cinara Curtis
from Picea mariana (Mill.) B.S.P. Can. Ent. 88: 706-708.
1956.
Brown, N. R. and Clark, R. C. Studies of predators of the
balsam woolly aphid, Adelges piceae (Ratz.) II An
annotated list of the predators associated with the balsam
woolly aphid in eastern Canada. Can. Ent. 88: 678-683.
1956.
Buckner, C. H. Population studies on small mammals of
southeastern Manitoba. J. Mammalogy 38: 87-97. 1957.
Buckner, C. H. Home range of Synaptomys cooperi. J.
Mammalogy 38: 132. 1957.
Condrashoff, S. F. Advance of the satin moth, Stilpnotia
salicis (L.) into the interior of British Columbia. Proc.
Ent. Soc. B. C. 53: 26-27. 1957.
Evans, D. A revision of the genus Poecilonota in America
north of Mexico (Coleoptera: Buprestidae). Ann. Ent.
Soc. Amer. 50: 21-37. 1957.
Grant, J. Notes on a variety of the western tent caterpillar,
Malacosoma pluviale (Dyar), Proc. Ent. Soc. B.C. 53:
1.6-18. 1957.
Hedlin, A. F. Studies on the balsam-fir seed chalcid,
Megastigmus specularis Walley. Can. Ent. 88: 691-697.
1956.
Miller, C. A. A technique for estimating the fecundity of
natural populations of the spruce budworm. Can. J. Zool.
35: 1-13. 1957.
Reid, R. W. The bark beetle complex associated with lodgepole pine slash in Alberta. Part II-Notes on the
biologies of several hymenopterous parasites. Can. Ent.
89: 5-8. 1957.
Ross, D. A. and Evans, D. Annotated list of forest insects of
British Columbia. Part V-Dioryctria spp. (Pyralidae),
Proc. Ent. Soc. B.C. 53: 10-11. 1957.
Wellington, W. G. The synoptic approach to studies of
insects and climate. Ann. Rev. Entomology. 2: 143-162.
1957.
The following single-page illustrated leaflets have just been.
issued.Publication 1000 The European pine shoot moth in.
Ontario
Publication 1001 The yellow-headed spruce sawfly in
Ontario
Publication 1002 The red-headed pine sawfly in Ontario
Publication 1003 The white pine weevil in Ontario
Publication 1004 The elm leaf beetle in Ontario
Copies may be obtained on request from:
Forest Insect Laboratory,
Box 490,
Sault Ste. Marie, Ont.
or
Information Service,
Department of Agriculture,
Ottawa, Ont.
EDMOND CLOUTIER, C.M.G., O.A., D.S.P., Queen's Printer and Controller of Stationery,
z
Ottawa, 1957.
CANADA
DEPARTMENT OF AGRICULTURE
SCIENCE SERVICE-FOREST BIOLOGY DIVISION
Vol. 13
REPORT
Number 3
May-June
1957
BI-MONTHLY PROGRESS REPORT
Published by Authority of the Right Hon. James G. Gardiner, Minister of Agriculture, Ottawa
CURRENT ACTIVITIES
ATLANTIC PROVINCES
Aerial Spraying Against Spruce Budworin in New
Brunswick-1956 —This is the fifth annual contribution to
the Bi-Monthly Progress Report summarizing immediate
results of this large-scale forest spraying program. The 1956
operation was the largest yet undertaken and covered approximately 2 million acres. Half of this represented respraying
of areas treated in other years, principally 1953, and the
other half involved new areas of severe attack, chiefly in the
central and northeastern areas of the Province. This raised
the net acreage treated one or more times to 4,610,000 and the
total acreage including respraying to 6,325,000. Approximately
3 per cent of sprayed areas has been treated 3 times and about
31 per cent has been treated twice.
Operations were carried out under the same management
as in previous years and costs were again shared equally by
Industry and the Provincial and Federal Governments. The
aerial fleet consisted of 89 Stearman spray planes and 12
Cessna single-engined observation planes. These operated
out of 11 airstrips, four of which were constructed in the fall
of 1955. Insecticide consisting of a solution of 1 pound technical grade DDT in 1 U.S. gallon of naphthenic solvent
(Imperial Oil No. 164) was formulated in New Brunswick for
the first time and was applied at the average emitted dose
of 1/2gal./creCostinudgpcrtionse
1952 have been $3.15, $1.40, $1.05, $0.85 and $0.80 per acre
for the respective years.
Difficulties were encountered in timing operations in 1956
owing to unusually delayed and erratic seasonal development
and to the complicating influence of heavy host flowering.
This phenomenon was general on balsam fir in New Brunswick for the first time in six years although heavy flower
crops had been produced by this species every 2nd or 3rd year
for at least 30 years previously. The effects of flowering
together with some shoot killing by late spring frosts tended
to invalidate techniques of assessing insect and host development that had proved useful in timing operations in previous
years. Development was found to vary widely within individual operational areas and operational difficulties were complicated by the necessity of spraying on a limited scale out
of most of the bases at once rather than at full capacity out
of a few bases selected in turn. Spraying commenced along
the Main S.W. Miramichi on June 6 from Dunphy airstrip;
the last flights were made from Home's Gulch airstrip in the
northwest corner of the Province on June 27.
Assessments of immediate results are based on data from
(1) 18 permanent sampling locations, 11 of which were sprayed
in 1956, and (2) 379 additional survey locations selected more
or less at random in sprayed and unsprayed areas and sampled for survival only. Population data from permanent plots
are expressed in terms of entire mid-crown branches for longterm studies and in terms of 18-inch branch tips for immediate assessments. The 18-inch unit was used in the postspray survey and counts were made according to a sequential
method devised for the purpose in 1956. Counts at all locations are supported by ocular estimates by trained observers
of degree of current and total defoliation on sample trees.
Studies of effects on tree growth and survival were continued
on a system of permanent plots and additional cruising was
undertaken to assess the extent of tree mortality in small
patches of advanced damage located by aerial survey.
Large-scale aerial and ground surveys of defoliation and
damage were again used to map the total extent of light,
moderate, and severe infestation and to obtain estimates of
hazard for 1957. The low-level line-strip technique used
in previous aerial surveys was retained for southern areas of
more recent attack. In the older outbreak areas a sketchmapping technique was reverted to in order to map areas
of advanced damage and imminent severe tree mortality.
Ground surveys included egg counts to estimate infestation
in 1957 and were modified only slightly from previous years
to allow for a shorter working period due to the delayed
season,
87604
An analysis of immediate results shows that survival in
sprayed areas at adult emergence averaged 89 per cent less
than in comparable unsprayed areas. This compares favourably with other years but the net preservation of the
current foliage crop, 25 per cent was relatively poor. The
factors that are likely to have contributed to indifferent
results in 1956 are:
(1) The flowering of host trees was favourable to budworm development but was unfavourable to the growth of
the trees.
(2) Optimum timing was difficult owing to the delayed
and erratic seasonal development. In some cases this was
further complicated by the difficulty of accommodating
operations to recommended timing schedules.
(3) In some areas late spring frosts aggravated the
effects of severe early feeding on the scanty foliage crop.
(4) Excessive exemption of patches of non-susceptible
forest in some areas produced a complicated boundary pattern that reduced the chances of accurate flying and uniform
coverage, and probably increased the loss of insecticide
through drift on to non-scheduled areas.
A number of the survey points were located in areas
treated by variations in dosage. The average assessments in
these areas are compared with those for standard dosage as
follows:
Dosage
lb./acre
Percentage reduction in budworm survival lb./acre
One app li cation Two applications
89
96
Percentage current foliage preserved 25
82
33
6
The relatively good results obtained from a double
application, one to two weeks apart, supported conclusions
reached in 1953 regarding the greater effectiveness of this
technique. Relatively poor results were obtained from a
dosage of 3/8 lb. DDT in 1/2gal.soventprc
Analyses of sample foliage provided counts of other
lepidopterous defoliators, parasites of the spruce budworm
that pupate on the branches, and predatory forms including
some known or suspected to attack the budworm. Results
were similar to those obtained in 1955. Post-spray populations of other defoliators averaged about 2 per cent of those
of the spruce budworm in unsprayed areas and were reduced
by 57 per cent in sprayed areas. Griselda radicana Wlshm..
was again the most frequently found, followed by Diorycta
reniculella (Grote) and Eucordylea sp. The effects on parasites and predators are summarized in the following Table:
Spraying history
Unsprayed, or
sprayed prior
to 1955
Spruce budworms Parasites Predators Percentage
population
reduction
in 1956 sprayed
areas
Sprayed • Sprayed
in
in
1955
1956
NUMBER OP INSECTS PER UNIT OF FOLIAGE
Parasites: budworms
Predators: budworms 188
23.6
1.1
78
19.8
2.5
21
7.0
0.7
89
70
36
SURVIVAL RATIOS
`
1:8
1:171
1:4
1:31
1:3
1:30
I
—
These data again reveal the interesting fact that these
parasites and predators are not reduced by spraying -to the
same extent as the host and that this result in proportionately
higher post-spray parasite/host and predator/host ratios in
that in unsprayed areas. Parasite species in.
sprayed
unsprayed areas (including areas sprayed prior to 1955)
occurred in the following order of abundance: Glypta fumiferanae, Apanteles fumiferanae, Meteorus trachynotus, and
dipterous parasites, being found in 84, 63, 16, and 13 per cent
of the samples, respectively. Percentage reduction of the
species by spraying was estimated to be 50, 25, 69, and 23
respectively. As in previous studies (Bi-Monthly Progress
Report 12(2), 1956) Apanteles appears to have been less
severely affected than Glypta, and this resulted in a reversal
of the relative predominance of these two species in sprayed
areas. The most abundant predators were coccinellids followed
by syrphids, pentatomids, aphis lions, and spiders. Aphids
and mites were not abundant in either sprayed or unsprayed
areas.
Large "flights" of adult moths were recorded less frequently than in 1955 and total catches were smaller at
most light traps operated in New Brunswick by staff of the
Fredericton and Green River Laboratories. Exceptions
include record catches in the extreme northwestern part of
the Province on several nights in early August and extraordinarily large invasions of the town of Campbellton,
on the nights of August 6 and 7. Infestation of 1956 sprayed
areas by the next generation averaged 179 egg masses per
100 sq. ft. of branch area. This was about 40 per cent less
than in unsprayed areas, where populations showed a tendency to increase over 1955. The highest populations of the
main outbreak area (roughly the northern half of the Province) were found in the east but numbers were sufficiently
high throughout the area that moderate to severe attack is
likely to be general again in 1957. Because of this and the
weakened condition of many stands following the severe
1956 season high hazard conditions (mortality expected to
result from 1957 attack in the absence of spraying) were
estimated to occur in all areas so far treated plus approximately 1/2milonacresfwhzdlongtesuar
boundary.
Comparisons between sprayed and check areas continue
to provide convincing proof that spraying has forestalled or
delayed the type of widespread damage that is characteristic
of full-scale budworm outbreaks. Aerial observations in particular reveal that unsprayed check areas in the Upper
Charlo and Kedgwick watersheds, each of about 20 to 30
square miles, present a neatly uniformly grey appearance
owing to partial or complete loss of foliage following 7 years'
continuous severe attack. The first mortality in these areas
was observed in 1954. The most advanced damage now
occurs in mature to overmature stands in the Kedgwick area
where as many as 60 per cent of firs above the suppressed
understory are now dead and the rest are dying. Figures
from younger stands in the Charlo area, including some
dating from the previous outbreak, reveal average mortality
in fir of 27 per cent by stems and 18 per cent by basal area.
Comparable figures for the same range of size classes in
spruce (2 inches D.B.H. and up) are 16 and 14 per cent
respectively but the difference arises chiefly from a heavier
concentration of fir mortality in the smallest diameter classes.
In both check areas, however, there remain patches of young
forest in which present mortality is negligible and prospects
remain good for recovery provided the infestation declines
within the near future.
Although protection in sprayed areas has generally been
good, its uneven and temporary nature became evident in
1956 from the appearance of advanced damage in scattered
patches throughout the older outbreak areas. Estimated total
extent of these areas was about 400,000 acres and mortality
in representative stands averaged about 22 per cent of all
fir above 2 inches D.B.H. As a general rule, however, these
stands are not as severely affected as those in check areas
since many of the remaining trees have responded well to
protection and show good prospects of surviving with continued protection.
Records are being analysed each year to determine the
rate at which mortality occurs in the various tree classes.
Although mature and overmature stands have been most
severely affected, early fir mortality within individual stands
has been largely concentrated in smaller diameter classes.
There is also evidence of a relationship to density of stocking
and predominance of fir. The following table summarizes
the crown class distribution of firs recorded as dead from
spruce budworm on permanent sample plots in 1955 and
1956.
Year of
tree
death
Percentage distribution of dead trees by crown classes
Crown class
Dominant
Co-dominant Intermediate
1955 1956 6
13
33
27
37
46
Together 10
29
42
Suppressed
Q
24
14
19
Plans for 1957 involve a continuation of the program
on the largest scale yet, probably involving 5 million acres—
F. E. Webb.
QUEBEC
Aerial Spraying Against Spruce Budworm in Quebec.
—1956.—In 1956, the third consecutive year of operations
in Quebec, 446,000 acres were treated in the Lower St. Lawrence and Gaspe regions. Respray areas amounted to about
10 per cent. To date, a total of 1,800,000 acres, comprising
close to one-half of the softwood stands in the Gaspe and
the eastern section of the Lower St. Lawrence, have been
treated. In 1956 the sprayed territories consisted mainly of
widely scattered and relatively small areas compared with
the three large blocks sprayed in 1955.
The operation was sponsored by Quebec Forest Industries
Association Limited, and the cost was shared jointly by the
Provincial Government and the participating companies.
Spraying operations were carried out under the management
of B. W. Flieger. The formulation of the spray, the dosage,
and the method of application were similar to those previously
described by Flieger (Bi-Monthly Progress Report 9 (5),
1953).
The program of biological assessment was carried out
from a newly established field station at New Richmond, by
a crew of ten employees of the Quebec Forest Biology
Laboratory and four employees of the Provincial Bureau of
Forest Entomology. Work on the egg-mass survey was
done by personnel of both organizations in cooperation with
employees of limit holders.
Timing of operations, based on insect development, was
determined by aerial surveys, and by ground reconnaissance.
Biological sampling was carried out from eleven permanent
plots and 218 temporary plots. Some of the plots were in
sprayed (1954, 1955 or 1956), others in adjacent unsprayed
areas. In 79 temporary plots, budworm populations were
assessed before and after spraying, while an additional 139
temporary plots were sampled only after spraying. In the
permanent plots, populations were counted on one 18-inch
branch tip from each of ten trees, and in the temporary plots
on the same unit length of branch from each of five trees.
All branch-samples were obtained from the midcrown of
co-dominant balsam fir trees by means of pole clippers.
Insect material from the permanent plots was reared for
parasite studies.
A defoliation and damage survey for the Gaspe Peninsula, adjoining regions of the Lower St. Lawrence, and Anticosti Island was conducted from the air. Extensive observations were made from the ground to confirm the aerial survey
in all regions but Anticosti Island. As in previous years a
survey was conducted to obtain information on the distribution and relative abundance of budworm egg masses throughout the infested territory. The procedure was essentially the
same as in 1955 (see Bi-Monthly Progress, Report 12 (2) ).
Spruce budworm populations were generally higher in
1956 than in 1955. Emergence in 1956 was later and development considerably more retarded than for the previous year
(see Bi-Monthly Progress Report 13 (1) ). Spraying began
on June 18, and lasted until July 1, areas at lower elevations
being treated first. Because of local differences in development, insecticides were applied nearly everywhere at the
optimum time, namely when the larvae were mostly in the
fourth and fifth instars.
At the time of the pre-spray samples (third instar), the
average population in unsprayed localities was approximately
24 larvae per 18-inch branch. In the localities treated in
1955, populations were relatively low with approximately
three larvae per 18-inch branch. In localities sprayed in 1954,
populations were as high as for unsprayed localities, indicating the reinfestation of these territories was fairly general.
In the post-spray samples the average number of insects
per 18-inch branch was 5.6 for unsprayed and 0.5 for localities
sprayed in 1956, giving an average control of 91 per cent.
In localities treated in 1955 the residual population was 59
per cent less, and in those treated in 1954 220 per cent
greater than in untreated localities.
The average defoliation of the current year's growth was
5 per cent in untreated localities. The localities treated in
1956 retained 48 per cent more, and those treated in 1955,
80 per cent more of the 1956 growth than untreated localities.
Defoliation of the current year's growth varied considerably
in localities treated in 1954 being generally higher in the
Patapedia than in the Metis Lake and Rimouski River
watersheds.
Total defoliation refers to the accumulated defoliation
since the first year of attack and was classified as light (1 to
2 years), moderate (2 to 3 years), and severe (3 years and
over). Results of the aerial survey indicated that in unsprayed territories total defoliation varied, the largest sector
of light defoliation occuring along the northeastern part of
the Gaspe Peninsula. Relatively large areas of moderate
defoliation occured in the interior of the Peninsula between
the Bonaventure and Grande Cascapedia rivers, and in the
southeastern region between Perce and the Grand Pabos
River. In most of the remaining unsprayed territory,
wherever mature stands of balsam fir occur, total defoliation
was severe. In stands sprayed in 19M and 1955, classification
of total defoliation becomes very complex since most of these
exhibit varying degrees of discontinuous defoliation, i.e. years
of severe defoliation followed by years of light or moderate
defoliation. Therefore, total defoliation in sprayed territories
cannot readily be compared with that in unsprayed territories and for this reason will not be discussed here.
The total area where the mortality due to budworm
defoliation occured covered approximatively 200 square
miles. Mortality was generally restricted to higher elevations
indicating that the epidemic probably started in stands growing on mountain tops and high plateaux. The greatest incidence of mortality prevailed in a band of territory about
6 miles wide and 60 miles long stretching from the headwaters of the Assemetquagan River to the Bonaventure River,
and in the region lying between the Patapedia and Matapedia
rivers. Tree mortality also occured, but more sparingly, near
Matane Lake, northwest of Metis Lake, and in the Rimouski
River watershed.
A total of 612 locations were sampled for spruce budworm eggs in 1956, 63 per cent by company personnel and
37 per cent by government crews. The pole pruner method
was used at 405 locations and the axe method in the remainder. The proportion of the locations sampled in each of
the unsprayed and sprayed areas is as follows: unsprayed
65 per cent; sprayed 1954, 6 per cent; sprayed 1955, 19 per
cent; sprayed 1956, 10 per cent. A total of 1,345 trees were
sampled with an average of 2.2 trees per location.
The average number of egg-masses per 100 square feet
of foliage was 259; numbers varied from 0 to a maximum
of 2,457. Negative samples were obtained in only 9 per cent,
but in 23 per cent of the locations the population exceeded
500 egg-masses, i.e. 2.5 times the number necessary to cause
severe defoliation.
Conditions as observed in 1955 and 1956 are compared
in the following synopsis:
TABLE I
LENGTH OF LARVAL PERIOD (DAYS)
Female
Non-infected
Year
1955 46
9
45
1956 28
11
61
The above figures indicate that there was an increase in
the number of egg-masses deposited in 11956. It must be
mentioned however that some mortality is expected, particularly at higher elevations, owing to the late deposition of
eggs.
The egg pouplation was generally high in unsprayed
areas, the watersheds situated between the Bonaventure
burn and the York River being the most heavily infested.
The northeastern section of the Peninsula was the only one
classified as lightly infested; high populations were found,
however, in localized areas such as Marsoui, Rivière à Claude
and the Dartmouth watershed.
In sprayed areas egg density varied depending upon the
number of years since spraying occured. In areas sprayed in
1954 an increase was recorded and the population was
generally heavy. In the areas sprayed in 1955, the sampled
locations were about equally divided between the light and
severe categories. The areas sprayed in 1956 were generally
well protected, although some reinfestation apparently occurred in a few cases.
Spraying operations will again take place in the Lower
St. Lawrence and Gaspe in 1957. On the basis of results
obtained through the defoliation and egg surveys it is planned
to spray approximatively 1,200,000 acres. All but one-tenth
of this territory will be treated for the first time. Operations
will encompass a territory extending from Rimouski to the
extreme eastern tip of the Peninsula—J. R. Blais and R.
Martineau.
Mal
Infected
Non-infected
Infected
No. insects 20
11
14
9
Total days 608
428
369
296
Mean days 30.4
38.9
26.3
32.9
The differences between the means of the infected and
non-infected insects in this and all succeeding tables were
compared by the "t" test; in Table I the differences were
found to be significant at the 1 per cent level. It is apparent
that the diseased larvae do develop at a slower rate than the
non-infected larvae. The increased period required for the
development of diseased larvae evoked questions concerning
the pupal and adult periods. To answer these questions, lateinstar larvae were removed from the Uxbridge forest and
reared individually until death; the number of days required
to pass the pupal and adult stages was recorded for male and
female insects, infected and non-infected. The effect of the
disease on the development of the pupae is shown in Table II.
TABLE II
LENGTH OF PUPAL PERIOD (DAYS)
Female
Non-infected
Male
Infected
Non-infected
Infected
No. insects 28
13
33
17
Total days 220
112
266
146
Mean days Percentage of Egg-mass populations
by categories
Light
Moderate
Severe
7.9
8.6
8.1
8.6
In the case of the females the difference was found to be
significant at the 1 per cent level, the difference between males
was significant at the 5 per cent level. It is apparent that
the non-infected pupae develop somewhat faster than infected
pupae. Although under test conditions the difference is small,
lower temperatures, which tend to increase the period of pupal
development, might increase the effect of the disease.
The length of the adult period of infected and noninfected adults was determined from the same material used
for the pupal measurements. The results are shown in
Table III.
TABLE III
LENGTH OF ADULT LIFE (DAYS)
Females
Non-infected
Males
Infected
Non-infected
Infected
No. insects 28
13
33
17
Total days 442
114
320
122
Mean days 15.8
8.8
9.8
7.2
The length of life of Perezia-infected adults is considerably shorter than that of non-infected adults, the differences
being significant at the 1 per cent level.
From the above results it is quite apparent that budworm
infected with Perezia fumiferanae develop at a slower rate
during both the larval and pupal stages and have a shorter
adult life than non-infected insects. Females are affectefd
more than males.—H. M. Thomson.
ONTARIO
The Effect of a Microsporidian Disease on the Rate
of Development of the Spruce Budworm.—While studying
the effects of a microsporidian disease of the spruce budworm
caused by Perezia fumiferanae Thom., it was noticed that the
Perezia-infected larvae seemed to develop much more slowly
than non-infected larvae. To check this observation, secondinstar larvae from the Uxbridge Forest, Ont., were forced out
of hibernation in the laboratory and reared individually until
pupation. The pupae were then examined for the presence
of the disease. This particular population was chosen because
approximately 30 per cent of the larvae were known to be
infected. Records were kept of the number of days from
emergence to pupation and of the sex of the larvae. The
results are shown in Table I.
BRITISH COLUMBIA
A Test of Three Disinfectants in Nursery Soil. —Three
soil disinfectants were tested at the Duncan forest nursery in
1956 for control of damping-off and weeds. They were:
chlorobromopropene (CBP), 4.4 oz. with emulsifier in 27 qts.
of water per 100 sq. ft.; ally' alcohol (AA), 4.4 oz. in 27 qts.
of water per 100 sq. ft., and dimethyl tetrahydrothiazine
thione (Mylone) at 4.4 oz. in 20 qts. of water per 100 sq. ft.
The experiment was limited to one rate for each material, and
to plots each 11.1 sq. ft. replicated four times. Highest
recommended rates were avoided because, if weather had
been cool, concentrations remaining at sowing might have
been phytotoxic. The weather, however, was normal. In
the four days before treatment mean air temperature was
50°F. with .01 in. of rain. Chemicals were applied to the
seed-bed May 4. In the thirteen days after treatment mean
air temperature was 55.8°F. with .09 in. of rain. Stratified
Douglas fir seed was then sowed May 17 and covered with
one-half inch of sandy soil relatively free of seeds and
pathogens. For the 53 days after sowing, mean temperature
was 60.5°F. with 4.07 in. of rain. The test area was not
irrigated. As in the rest of the nursery, the soil was sandy
loam with porous subsoil. This area, which had been covercropped several years, showed a low incidence of damping-off
and weed emergence. The bulk of the weed growth was
formed of a few early-emerged weeds averaging 31/2 per control
plot and I per treated plot. The freedom of Douglas fir on
the AA and Mylone plots from smothering was obviously
significant compared with the controls. Further, the average
numbers of weeds of all sizes counted on the plots, control,
CBP, AA, and Mylone were, respectively, 46.0, 34.3, 21.0*,
and 21.8*. (*Significant. L.S.D. at .05 was 18.4). At the rates
used CBP was erratic in effect, AA appeared to control spring
emergence of erect knotweed, wild buckwheat, common chickweed, sand spurrey, and orchard grass, and Mylone appeared
to control the weeds named except orchard grass. Other
weeds, notably clover and fine grasses, were present but were
small and of sporadic occurrence. Many of the weeds counted
after 53 days were assumed to have seeded in after the
chemicals dissipated and, although willow was obviously
present, no attempt was made to identify weeds in the
cotyledon stage.
Increases in stand of Douglas fir were associated with soil
treatments but were non-significant. The increases with CBP,
AA, and Mylone were 10.3, 3.3, and 3.3 per cent, respectively,
53 days after sowing. Douglas fir seedlings were a normal
green in the treated plots, but in two of the four controls
they were chlorotic, possibly from competing and shading
weeds or from low availability of nitrogen which sometimes
is associated with growth of microorganisms on green manure
in the soil.
Under 1956 conditions and rate of application of the
disinfectants the results suggest the following. Only the seedbed and not a cover soil that is reasonably weed- and diseasefree need be treated. Partial soil sterilization may sometimes
increase the stand of Douglas fir seedlings possibly as an
indirect result of increasing the vigour of the seedlings, as
well as by decreasing pathogens in the soil. For AA and
Mylone, the rate tested shows promise if only susceptible
weeds are present or if resistant weeds are few.
Further tests of the soil-disinfectant method of weed
control appear worth while since Douglas fir tends to be
sensitive to post-emergence application of selective herbicides.
In addition, the increases in stand from soil disinfection were
comparable in magnitude, though not in statistical significance,
with the 4.3 per cent increase in stand 56 days after sowing,
EDMOND CLOUTIER, C.M.G., O.A., D.S.P.,
obtained by treating Douglas fir of the same seed-lot with
Thiram before sowing it in the same part of the nursery.P. J. Salisbury.
RECENT PUBLICATIONS
Atkins, M. D. and Chapman, J. A. Studies on nervous system anatomy of the Douglas fir beetle, Dendroctonus
pseudotsugae Hopk. Can. Ent. 89: 80-86. 1957.
Basham, J. T. The deterioration by fungi of jack, red, and
white pine killed by fire in Ontario. Can. J. Bot. 35:
155-172. 1957.
Bird, F. T. On the development of insect viruses. Virology
3: 237-242. 1957.
Clark, J. and Gibbs, R. D. Studies in tree physiology IV.
Further investigations of seasonal changes in moisture
content of certain Canadian forest trees. Can. J. Bot.
35; 219-253. 1957.
Kinghorn, J. M. Two practical methods of identifying types
of ambrosia beetle damage. J. Econ. Ent. 50: 213. 1957.
Kushner, D. J. Effect of alcohols on the synthesis of lecithinase by Bacillus cereus. Nature 179: 781-782. 1957.
Lyons, L. A. Insects affecting seed production in red pine II.
Dioryctria disclusa Heinrich, D. abietella (D. and S.),
and D. cambiicola (Dyar). Can. Ent. 89: 70-79. 1957.
Lyons, L. A. Insects affecting seed production in red pine
III. Eucosma monitorana Heinrich, Laspeyresia toreuta
Grote, Rubsaamenia sp. and other insects. Can. Ent.
89: 150-164. 1957.
Morris, R. F. The interpretation of mortality data in studies
on population dynamics. Can. Ent. 89: 49-69. 1957.
Parker, A. K. Europhium a new genus of the Ascomycetes
with a Leptographium imperfect stage. Can. J. Bot. 35:
173-179. 1957.
Prebble, M. L. and Graham, K. Studies of attack by ambrosia
beetles in softwood logs on Vancouver Island, British
Columbia. For. Sci. 3: 90-112. 1957.
Redmond, D. R. The future of birch from the viewpoint of
diseases and insects. For. Chron. 33: 25-30. 1957.
Redmond, D. R. Infection courts of butt-rotting fungi in
balsam fir. For. Sci. 3: 15-21. 1957.
Reid, R. W. The bark beetle complex associated with lodgepole pine slash in Alberta. Part III-Notes on the biologies of several predators with special reference to
Enoclerus sphegeus Fab. and two species of mites. Can.
Ent. 89: 111-120. 1957.
Silver, G. T. Separation of the species of arbovitae leaf
miners in New Brunswick. Can. Ent. 89: 97-107. 1957.
Silver, G. T. Studies on the arbovitae leaf miners in New
Brunswick. Can. Ent. 9: 171-182. 1957.
Vaartaja, O. Photoperiodic responses in seedlings of northern
tree species. Can. J. Bot. 35: 133-138. 1957.
Virkki, N. Structure of the testis follicle in relation to evolution in the Scarabaeidae. Can. J. Zool. 35: 265-277. 1957.
Queen's Printer and Controller
•
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Stationery, Ottawa, 1957.
CANADA
DEPARTMENT OF AGRICULTURE
SCIENCE SERVICE—FOREST BIOLOGY DIVISION
Vol. 13
REPORT
Number 4
July-Aug.
1957
BI-MONTHLY PROGRESS REPORT
Published by Authority of the Hon. Douglas S. Harkness, Minister of Agriculture, Ottawa
CURRENT ACTIVITIES
ATLANTIC PROVINCES
Sampling Techniques for the Overwintering Stage of
the Larch Casebearer.—Population records of the larch casebearer, Coleophora laricella Hbn., have been maintained since
1949 on a study plot at Fredericton, New Brunswick. Certain
of the data have already been used to describe some
aspects of population distribution within the tree and in the
stand (Webb, F. E., 1953. An ecological study of the larch
casebearer. Dissertation Abstr. 13(5) : Univ. Microfilms, Ann
Arbor, Mich.). Spare-time observations have been continued
on the plot since 1952 to measure population trends between
and during outbreak periods and to assess the role of certain
control factors, chiefly the introduced parasites Chrysocharis
larricinellae (Ratz.) and Agathis pumilus (Ratz.) first released
in the area in 1943. This has involved population counts
twice-yearly to measure (1) overwintering populations and
(2) populations at the time of pupation and emergence of
adults. This is a report of progress in developing sampling
methods for the overwintering stage.
Counts for the period 1950-1956 were made at three
crown levels for each of 50 tagged trees covering a range of
infestation from very high to very low. Sample branches
were cut at random from about the centre of each crown
section and a count was made of the number of casebearers
on twig growth of the most recent year per 100 buds or needle
fascicles. Analysis showed a highly significant variation in
population between crown levels, greater than that between
trees, with larvae/bud ratios usually highest at the base of
the crown and decreasing toward the tip. This and nonuniform distribution within the branches would have to be
accounted for in designing a sampling method to measure
absolute populations expressed, for example, in numbers of
insects per acre. For comparing infestation levels from place
to place and from year to year, it is more convenient to
restrict the universe to a given crown level and to express
counts in terms of population intensity, i.e., number of larvae
per unit of food. Lateral fascicles of needles (so-called
"short-shoots") provide convenient units for this purpose; in
the overwintering stage these are referred to as "buds". The
sampling methods described here have been developed for the
measurement of population intensity in the lower crown from
which samples may be collected quickly and easily without
the use of special apparatus. The recommended method of
counting individual samples is to examine entire twigs until
the fascicle or bud count equals or exceeds 100, as the use
of partial twigs to reach exactly 100 buds may introduce a
bias because of non-uniform distribution of casebearers on the
twig. Population intensity is calculated in terms of individual
units but may be expressed in terms of 100 units to allow a
more convenient placement of decimal points. Tallies of
feeding or pupated casebearers are usually made in the field
as the samples are drawn. Twig samples for counts of the
overwintering stage may be more conveniently placed in
marked bags and analysed later under more convenient conditions in the laboratory.
Calculations of required sample size to ensure a minimum
statistical reliability of population estimates are based on
estimates of variance between trees and within the specified
crown level. These were obtained from replicated lowercrown counts for infestation levels ranging from very high
to very low. The original counts were first transformed to
logl c(x -}- k/2) to randomize the negative binominal relationship between mean and variance. The constant k was computed as the common weight value for the population range
represented in the data (Bliss and Calhoun, 1954. An outline
of Biometry, Yale Co-Operative Corporation, New Haven,'
Conn.). In most cases between-tree variance was greater
than that within the crown level, but this was proved signifi87606
cant only at very high levels of population. This relationship
between inter- and intra-tree variance may be the; general
rule for populations of forest defoliators and calls for 'greater
emphasis on inter-tree sampling than on replication within
the crown level.
The following table has been calculated using appropriate
components of variance to show the various combinations of
samples per tree and numbers of trees required to define
overwintering populations so that standard error is within
10% of the mean.
Number of
samples
per tree
2
4
Infestation level
(Number of overwintering casebearers/100 buds)
I
1
5
20
10
I
Number of trees required
40
'I
;80.'
101
34
28
25
24
23
69
23
19
17
17
16
58
20
16
15
14
53
18
15
13
13
12
The optimum combination of trees per plot and samples
per tree is a function of the relative time required to move
from tree to tree compared to the time required to obtain.
individual samples within the tree. This will be influenced
by several variables including ease of movement within the
stand, distance between sample trees and whether special
equipment such as pole pruners is required. It will also
depend upon whether counts are made in the field or in the
laboratory. In the latter case, counting time is not a limiting
factor in the field procedure and should be excluded from the
calculations. The following shows the optimum number of
samples per tree for various time-study ratios:
Ratio of time required to move from
tree to tree/time required to
obtain an individual sample
within the tree
1:1 2:1to3:1 4:1 to 7:1 8:1 to 11:1 Optimum
number
of samples
per tree
1
2..`
3
4
Limited time-studies involving collecting time only indicated average ratios in the range 4:1 to 7:1 for the sampling
of roadside tamarack stands by experienced personnel at
Fredericton. This suggests that 3 samples per tree is the
optimum for this type of work.
An additional objective of these studies has been the
development of a quantitative sampling system for the more
extensive purposes of the Forest Insect Survey. A tentative
counting procedure involving a fixed sample-size has been in
use since 1953 to measure population intensity at the completion of the feeding stage at more than 50 permanent
sampling stations in the Atlantic Provinces. (Ann. Repts.
For. Insect Survey, Div. For. Biol., Can. Dept. Agric., Maritime Provinces section, 1953-56) Beginning in the present
season tests are to be made with the co-operation of staff
of the Forest Insect Survey of the following sequential
sampling system for the overwintering stage. The objective
of the sampling is to classify overwintering populations, within a probability of 90 per cent, in three levels according to
potential infestation. The potential is said to be "high"
when mean population intensity equals 40 or more overwintering casebearers per 100 buds, since previous studies
indicated that this level of population at the feeding stage
usually resulted in complete browning of host trees. Infestation potential is defined as "moderate" for overwintering
populations from 10 to 20 per 100 buds, and "low" for
mean populations of 5 or less. The following table is for
the use of counters:
CUMULATIVE NUMBER OF OVERWINTERING CASEBEARERS
PER 100 BUDS
Infestation potential
Sample
No.
r
2
3
4
5'
6
7
8
9
10 Low
Uncertain
Moderate
Uncertain
High
0-16
5-22
12-29
19-36
26-43
33-50
40-57
47-65
54-71
61-79
23-27
30-55
37-83
44-111
51-139
58-167
66-195
72-223
80-251
0-52
28-80
56-108
84-136
112-164
140-191
168-219
196-247
224-275
252-303
53 or more
81
109
137
165
192
220
248
276
304
4 or less
11 " "
18 "
25 "
32 ` "
39 " "
46 "
53 ` "
60 "
CC
CC
CC
CC
CC
et
CC
CC
le
CC
CC
The table is used as follows: A single count will suffice
only if it exceeds 52 casebearers on the first sample. Otherwise additional samples must be drawn until the accumulated
counts fall within the limits for "low", "moderate" or "high",
after which sampling may be discontinued. Calculated
operating characteristics of the table indicate that the required
number of samples should average between three and four.
Since samples will not be counted as they are drawn in the
field it is proposed for the first season to collect a fixed
number of 10 samples at each location, one per tree to ensure
a degree of inter-tree replication. The sequential system will
be applied to laboratory counts and excess samples will be
discarded. It is probable, however, that 10 samples per
location may prove unnecessarily excessive and may be reduced for future seasons.
The analysis will be continued as time permits to compute
similar tables for use in sampling populations at the completion of the feeding period. Results of the Forest Insect
Survey sampling will be studied to test the possibility that an
improved sampling schedule can be developed for this insect
involving counts of the overwintering stage to measure infestation trends, and restricting observations later in the
generation to ocular assessments of defoliation and damage
and collections for parasite rearings. This would have the
advantage of shifting a time-consuming sampling task to
a . less-crowded period in the Forest Biology Ranger work
schedule.
F. E. Webb.
ONTARIO
A note on the Predation of Spruce Budworm Pupae.
—During the summer of 1956, considerable predation of
spruce budworm (Choristoneura fumiferana (Clem)) pupae
was noted in the Uxbridge Forest, Ont. To obtain an estimate
of this predation, 400 pupal sites were examined at random
throughout the infestation and the pupae classified as whole
or attacked by predators. If the predators were caught in
the act, a tentative identification was made. This survey
was conducted three days before the start of adult flight;
hence it may be assumed that the bulk of the population
was in the pupal stage. The results of the examination are
shown below:
CONDITION OF PUPAE
Attacked by Predators
Whole Bud- worm
Number....
327
Percentage..
81.8
10
2.5
Coleop- Dioryc- Syrphitera
tria
dae
9
2.2
23
5.8
2
0.5
Unknown
Total
29
73
7.2
18.2
All observed predation by budworm larvae involved
sixth-instar larvae feeding upon new pupae; pupae less than
24 hours old were probably selected because of their soft
pupal cases. It is possible that predation by budworm larvae
was unusually high in this survey as approximately 40 per
cent of the Uxbridge population was infected by a microsporidian disease that retards larval development. This
resulted in more larvae than usual being present while the
bulk of the population was in the pupal stage.
The Coleoptera found feeding on budworm pupae were
adult Elateridae and Coccinellidae.
Dioryctria reniculella (Grt.), the spruce coneworm, was
the most commonly encountered pupal predator. This insect pupates slightly later than the budworm, and hence the
last-instar larvae are able to feed upon the defenceless budworm pupae. Frequently a Dioryctria pupa was found amid
the debris of a budworm pupa. (See also Warren, G. L.
Bi-monthly Progress Report 10 (3) :3, 1954).
Dipterous larvae were twice found feeding on budworm
pupae; these are believed to be larvae of the Syrphidae,
but positive identification was not made.
Pupal debris only was found in 72 per cent of the pupal
sites; as the insects responsible could not be identified, these
cases must be classified as "unknown". It is possible that
nocturnal predators, in addition to those listed, may have
contributed to this mortality.
In addition to the insects mentioned in the table, ants
may be of considerable importance as predators. These insects were not encountered during the survey but have been
observed feeding on pupae on other occasions. A cage
placed 4 feet off the ground and containing a large number
of pupae was repeatedly invaded by small reddish-brown
ants, which carried off many of the pupae. If these ants
behave in the same fashion towards pupae in their natural
sites, considerable mortality might result but would not be
recorded in the present survey.
Insect predators had caused 18 per cent pupal mortality
by the time the census was taken and this mortality would
obviously be greater by the time the adults had emerged.
This is a considerable mortality for a comparatively short
period in the budworm life-cycle, and indicates that predacious insects may be of notable importance in some areas.
—H. M. Thomson.
PRAIRIE PROVINCES
Sawflies of the Genus Platycampus Schiodte on
Trembling Aspen in the Canadian Prairies. —Four species
of Platycampus were listed in Hymenoptera of America north
of Mexico (U.S.D.A., Agric. Monog. 2: 35-36. 1951). However, the host plants were not given for any of the species.
According to Ross (Ill. Biol. Monog. 15(2) : 82. 1937) the
status of the species of Platycampus is indefinite. Consequently, any biological information greatly assists in the
determination of the various species.
To date only two of the four recognized species of
Platycampus, have been found in the Prairie Provinces. Both
were feeding on the foliage of Populus tremuloides Michx.,
and have been tentatively identified as Platycampus americanus (Marl.) and P. albostigmus (Roh.).
Larvae of these species have an enlarged thorax; conical,
4-segmented antennae; a pair of prolegs on each of abdominal
segments 2-7 and postpedes on segment 10. They were
collected in late July to mid-September, and feeding was
characterized by holes in the leaves of trembling aspen.
Mature larvae drop to the ground and construct a doublewalled cocoon in the soil; they emerge as adults the following
spring.
The two species can be readily distinguished in the larval
stage by colour and markings. The species identified as P.
albostigmus (Roh.) has a yellow-green body and two black
patches on the thorax, with a faint mid-dorsal line. P.
americanus (Marl.) has a greenish-black dorsum with light
coloured transverse spots on it, and a light green ventrum.H. R. Wong.
ROCKY MOUNTAIN REGION
Pitch Nodule Maker in Banff` National Park. —In the
summer of 1956, during the course of other investigations,
observations were made on the occurrence of a pitch nodule
maker on lodgepole pine. During lodgepole needle miner
sampling, 8 pitch nodules were recovered from a total of
4080 branches. In addition, special search for the nodule
maker was made in three locations as follows:
1. The junction of the new Trans-Canada Highway
and the Banff.-Jasper road. The stand was even-aged,
pure lodgepole pine, about 55 years old, average height
30 feet. A total of 20 trees was examined; 15 contained
nodules, with fresh nodules on 9 of them. There were
10 fresh nodules in all, more than the number apparently
one or more years old.
2. Mount Eisenhower Field Station. Fifty trees,
mostly regeneration, were examined. All but five were
11 feet high or less. Only 18 nodules were found and
these all occurred on trees taller than 9 feet. There
were three fresh nodules and there appeared to be no
change in number from the previous year's attack.
3. Approximately 5 miles west of the field station
on the Kootenay Park highway. The stand is very dense,
pure lodgepole pine, about 11 feet in height. A total
of 70 trees was examined, 50 from inside the stand, 20
from the border. Growth was much better in the latter.
Only three old attacks were found on the inner trees,
11 on the border trees. There were no fresh attacks.
Considering all samples, it was evident that the insect
has a 2-year life cycle, 1956 being predominantly a larval
• year. Of the 13 fresh nodules found, nine contained larvae
of about the same size; three contained parasitized larvae
and one contained a live pupa. The larvae remained alive
until fall and obviously would have overwintered as such.
One of the parasites failed to emerge. The adult material
was sent to the Systematics Division, Ottawa, and was
identified as follows:
1 Petrova metallica Bsk. (Ident. by T. N. Freeman).
1 Phrynofrontina sp. (Ident. by G. Shewell).
2 Hyssopus benefactor (Cwfd.) (1 female, 1 male) (Ident.
by O. Peck) .
The male and female Hyssopus were found in the same
nodule feeding on a Petrova larva. They formed naked black
pupae and emerged August 6. The Phrynofrontina sp. was
found in the larval form on June 14 and emerged July 17.
The Petrova specimen was in the pupal stage on June 14 and
emerged July 5, 1956.—R. W. Stark.
Observations on Coryne sarcoides (Jac q.) Tul.—In
earlier reports (10(4): 3-4-1954; 11(6) : 3. 1955), the occurrence and distribution of Coryne sarcoides in the heartwood
of decayed and healthy trees in Alberta were considered in
some detail. Although there was no evidence that this fungus
could cause decay, its relatively high incidence in living trees
and its frequent association with decay fungi indicated that
it might influence the development of decay. During the
past two years laboratory experiments and field observations
have provided further data on this interesting fungus.
The incidence of C. sarcoides in lodgepole pine and white
spruce was determined by examining records of isolations
made from samples of decay collected during 1955 and 1956
in various localities in Alberta. Consistent with the earlier
observations, the incidence of C. sarcoides was greater on
spruce than on lodgepole pine, and the fungus occurred more
frequently with brown rots than with white rots. The fungus
was associated with 7.5% of 335 samples from lodgepole pine
and 35% of 138 samples from white spruce. The incidence
of C. sarcoides in samples from black spruce, Douglas fir, and
balsam fir was about the same as that obtained for white
spruce. Eight decay samples from balsam poplar and 75
decay samples from trembling aspen were examined during
this work but these failed to yield cultures of the fungus.
The survey confirmed that C. sarcoides is the most common
organism occurring in the heartwood of living white spruce.
The previous data concern the occurrence of C. sarcoides
in living trees. By using data obtained from a study dealing
with the succession of fungi associated with the deterioration
of lodgepole pine slash at Strachan, Alberta, it has been
possible to examine the occurrence of this fungus in slash
from trees at intervals of 2, 3, and 4 years after felling. The
results shown in Table I are based on isolations made from
slash from 21 lodgepole pine trees which had been randomly
selected each year for the purpose of studying fungal successions.
TABLE I
THE INCIDENCE OF Coryne sarcoides IN LODGEPOLE PINE
SLASH IN RELATION TO THE NUMBER OF YEARS AFTER FELLING*
No. of
after
fchling
No. of rot
samples
examined
No. of samples
yielding
C. sarcoides
Percentage
of
occurrence
2
209
15
7.2
3
155
16
10.3
4
260
36
13.8
*Trees were felled in 1952.
In the three years, 1954-1956, the incidence of C. sarcoides
almost doubled in the slash which might indicate that this
fungus was assuming dominance and replacing certain heartrot fungi. However, it is not known to what extent the
replacement of rot-fungi by C. sarcoides occurs, although the
fact that this fungus is frequently isolated from the incipient
and advanced decay, often to the exclusion of the causal
wood-destroying fungus, suggests that some replacement of
decay fungi occurs in the living tree. The presence of this
fungus in the 4-year-old slash suggests that replacement
of rot fungi may continue throughout the course of succession.
Recently, studies have been made in the laboratory with
several isolates of C. sarcoides in an attempt to gain information regarding its function in the development of decay.
Tests made to determine its action on wood showed that
blocks of wood infected with this fungus had little .or no loss
in weight after incubation for periods of from 3 to 5 months,
whereas, after 3 months, control blocks infected with cultures
of wood-destroying fungi had lost up to 20% of their weight.
In the experiments with C. sarcoides there were few changes
in the gross characteristics of the blocks although several
of the blocks bore fruiting-bodies (conidial stage) of the
fungus and these were associated with a purple staining of
the wood. Microscopic examination of the stained tissues-
revealed the fungus at depths of several millimetres below
the surface of the wood; hyphae were observed penetrating
the cell-walls as well as passing through the bordered
pits. The bore-holes formed by the hyphae passing
from cell to cell were extremely thin, the hyphae being
much constricted at each bore-hole. The formation of such
minute bore-holes and constricted hyphae appear to be
characteristic of non-decay-producing fungi and has been
associated with the inability of these fungi to penetrate the
cell-wall by enzymic action. However, the ability to attack
cell-wall components by enzymes cannot be entirely lacking
in C. sarcoides since tests have shown that most isolates of
this fungus are able to attack cellulose, some isolates being
more active in this respect than isolates of wood-destroying
fungi. It is possible that certain constituents of the wood
are decomposed by the enzymic action of C. sarcoides but
that the action is too slow or of a kind that cannot be
measured by the loss in weight method. Further studies
must therefore aim at determining by other means the
effect on wood by C. sarcoides.
Cultural studies on the interaction between C. sarcoides
and wood-destroying fungi have been continued with some
interesting results. Previously, it was noted (11(6) :3. 1955)
that C. sarcoides was completely overgrown by a number of
species of wood-destroying fungi when the fungi were grown
together on malt agar. Recently, by screening a larger
number of isolates, certain strains of C. sarcoides have been
found to produce an antibiotic which is antagonistic to several
species of wood-destroying fungi. Although many of the
isolates tested were quite inactive, several were very active
in preventing the growth of Coniophora puteana (Schum.
ex Fr.) Karst. on agar plates, and the antagonism of one
isolate was shown to the extent that decay by C. puteana
and Polyporus tomentosus Fr. was reduced by from 50 to
75% of that obtained in controls. Further investigations are
planned to determine the incidence of strains antagonistic
against wood-destroying fungi.—D. E. Etheridge and Elizabeth
Carmichael.
BRITISH COLUMBIA
Volatile Wood Constituents in Relation to Ambrosia
Beetles. —Earlier studies (Bi-Monthly Progress Report 12(1) :
3-4, 1956) reported by us indicated that volatile substances
obtained by carrier gas distillation from Douglas fir sapwood
attractive to Trypodendron lineatum induced them to bore
into otherwise non-attractive bark treated with these extracts.
Gas chromatographic methods, specially designed to suit
the material of this study, are now proving capable of
separating the extracts into pure constituents. A number of
components is now indicated. Furthermore, the method has
detected differences, of as yet undertermined significance,
between extracts from different trees. Each gas chromatogram
consists of a line on a chart showing a series of peaks, each
of which is caused by one of the constituents of the mixture
under test. Under constant operating conditions the position of each peak with respect to the starting point is
characteristic of it, and of a size proportionate to the quantity
present.
The two major constituents of gas-distilled extracts from
both attractive and non-attractive wood possess retention
volumes identical with those of alpha- and beta-pinene. The
peak size showed that the quantity of the alpha isomer
exceeds that of the beta in the ratio of about 12 to 1.
The identity of the two chief constituents as alpha- and
beta-pinene has been confirmed by infra-red absorption spectra
determined by Dr. R. H. Wright of the B.C. Research
Council, and by nuclear magnetic resonance spectra determined by Dr. C. Reid of the Department of Chemistry,
University of British Columbia. We wish hereby to acknowledge our gratitude to them for this generous co-operation.
Trypodendron lineatum adults caught in flight this spring
failed to attack bark surfaces treated with alpha- or betapinene or with extracts from new wood containing large
amounts of these substances. There is even slight evidence
that these materials are a deterrent to boring by the
beetles.—A. E. Werner and K. Graham.
The Relation of Bark Moisture to the Development of
Canker Diseases with Particular Reference to Cryptodiaporthe Canker on Willow.—During the dormant season of
1956-57 it was observed that heavy mortality was occurring
in young shoots of willow in Vancouver as the result of stein
cankers with the associated fungus Cryptodiaporthe salicina
(Curr.) Well. Further, an examination of the annual ring of
wood beneath the lesions demonstrated that canker development had occurred after the end of the 1956 growing season.
In February, numerous incipient cankers in an actively growing condition could be found on a single stem, the lesions
originating at buds, lenticels, and insect wounds. A survey
for cankers on other hosts led to the general observation that
this type of disease appeared to be more common in Vancouver than in areas examined in Eastern Canada. It
appeared that the moderate climate of Vancouver may be
favourable to the continued spread and growth of C. salicina
(and other pathogens causing canker diseases) during the
dormant season when the host bark tissues were low in
moisture and in an otherwise inactive condition.
During the period from September, 1956, to April, 1957,
except for the months of December and January, the monthly
average temperatures were higher than the minimum required
for the growth of C. salicina on potato dextrose agar.
Laboratory experiments on the development of natural
and artificially induced cankers have proved that canker
growth is rapid in bark with a moisture content of 50 to
55 per cent of the weight of the green bark. The moisture
content of the bark of dormant willow falls within this range.
An increase in bark moisture to approximately 60 per cent
resulted in a cessation of canker growth. Such an increase
occurs with the breaking of dormancy. The bark moisture
content of willow in the field from April to June has ranged
from 66 to 72 per cent, which has coincided with no further
canker growth and the production of callus tissue by the
host around the margins of lesions which are excluding the
diseased areas.
Little variation was evident in the bark moisture content
of different dormant cuttings. However, dormant infected
cuttings planted in pots in the laboratory varied in their
ability to increase and maintain bark moisture at a level
above 60 per cent, in this way preventing further canker
growth. It was evident that the bark moisture content increased more rapidly and to higher levels in cuttings with
dark green bark tissues than in cuttings with yellowishgreen or brownish-green bark. Apparently the rate and
degree of rise in bark moisture was correlated with the
photosynthetic capacity of the bark tissues or, in other
words, the general vigour of the cuttings.
The present study illustrates the importance of bark
moisture as it affects the condition of the host and the
expression of disease. Under temperature conditions within
the range for the growth of the pathogen a determination
of bark moisture at any season or locality may provide a
valuable index into the relative susceptibility or resistance
of willow to Cryptodiaporthe canker.
It has been common practice- in forest pathology to
examine the trees on large numbers of sample plots to
correlate the incidence of canker diseases with complex
ecological and climatic factors. Frequently a compilation
of the results led to a number of multiple correlations
which are most difficult to assess or define. The present
studies indicate the possibility of using a more direct approach
through the investigation of moisture content, and determining its importance to the host and pathogen in the specific
EDMOND CLOUTIER, C.M.G., O.A., D.S.P.,
tissues that are being invaded. With this information it
may prove a simple matter to correlate disease vulnerability
with the more complex ecological and climatic factors.J. E. Bier, Professor of Forest Pathology, University of
British Columbia, Vancouver.
RECENT PUBLICATIONS
Atkins, M.D. An interesting attractant for Priacma serrata
(Lec.). Can. Ent. 89: 214-219. 1957.
Bourchier, R. J. Variation in cultural conditions and its
effect on hyphal fusion in Corticium vellereum. Mycologia
49: 20-28. 1957.
Cram, W. H. and Vaartaja, O. Rate and timing of fungicidal
soil treatments. Phytopathology 47: 169-173. 1957.
Etheridge, D. E. Differentiation of white- and brown-rot
fungi by an oxidase reaction. Nature 179: 921-922. 1957.
Finnegan, R. J. Elm bark beetles in southwestern Ontario.
Can. Ent. 89: 275-280. 1957.
Gardiner, L. M. Deterioration of fire-killed pine in Ontario
and the causal wood-boring beetles. Can. Ent. 89:
241-263. 1957.
Greenbank, D. O. The role of climate and dispersal in the
initiation of outbreaks of the spruce budworm in New
Brunswick- II . The role of dispersal. Can. J. Zool.
35: 385-403. 1957.
Harvey, J. K. Improved technique for inflating and mounting insect larvae. Can. Ent. 89: 280-283. 1957.
Hord, H. H. V., van Groenewoud, H., and Riley, C.G. Low
temperature injury to roots of white elm. For. Chron.
33: 156-163. 1957.
Kushner, D. J. An evaluation of the egg-yolk reaction as
a test for lecithinase activity. J. Bacteriology 73: 297-302.
1957.
Kushner, D. J. and Heimpel, A.M. Lecithinase production
by strains of Bacillus cereus Fr. and Fr. pathogenic for the
larch sawfly, Pristiphora erichsonii (Htg.). Can. J.
Microbiol. 3: 547-551. 1957.
Lyons, L. A. Insects affecting seed production in red pine.
IV. Recognition and extent of damage to cones. Can.
Ent. 89: 264-271. 1957.
Pomerleau, R. and Ray, R. G. Occurrence and effects of
summer frost in a conifer plantation. Can. Dept. North.
Aff. & Nat. Res., For. Br. Tech. Note 51. 1957.
Raizenne, H. Forest sawflies of southern Ontario and their
parasites. Pub. 1009 Can. Dept. Agr. 1957.
Rose, A. H. A technique for differentiating annual rings in
increment cores from diffuse porous woods. For. Chron.
33: 139-140. 1957.
Thomson, M. G. Appraisal of western hemlock looper infestations. For. Chron. 33: 141-147. 1957.
Wellington, W. G. Individual differences as a factor in
population dynamics: the development of a problem.
Can. J. Zool. 35: 293-323. 1957.
Queen's Printer and Controller of Stationery, Ottawa, 1957.
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CANADA
DEPARTMENT OF AGRICULTURE
SCIENCE SERVICE-FOREST BIOLOGY DIVISION
Vol. 13
REPORT
Number 5
Sept.-Oct.
1957
BI-MONTHLY PROGRESS REPORT
Published by Authority of the Hon. Douglas S. Harkness, Minister of Agriculture, Ottawa
CURRENT ACTIVITIES
PRAIRIE PROVINCES
Aphids of the Genus Cinara Curtis in Canada. —Seven
species, which apparently have not previously been found in
Canada, have recently been identified and added to the
reference collection. These species, and the host trees they
were collected from, are as follows:
Host Tree
Species
Picea glauca
Pinus monticola
Abies grandis
Pinus contorta var. latifolia
Pinus banksiana
Juniperus scopulorum
Picea engelmannii
Cinara braggii (Gillette) " ferrisi (Swain) " occidentalis (Davidson) " oregonensis (Wilson) " pinivora (Wilson) " sabinae (Gillette and Palmer) " vandykei (Wilson) The various species of Cinara were highly selective in the
sites that they occupied on the host trees. Some species, such
as C. fornacula Hottes, were always found on the small twigs
or current shoots. Other species, such as C. curvipes (Patch),
although they may begin feeding on the twigs in the early
spring, occur on the larger limbs or trunks throughout most
of the season. The length of the rostrum has been found
to be related to the feeding site. The species in which the
rostrum is short are those that are invariably found feeding
on the new shoots, twigs, or small branches. Species which
feed on the larger limbs or trunk have long rostrums. It is
thought that this relationship between the feeding site and
the length of the rostrum will prove useful in dividing the
genus into groups of similar species, as the first step in
devising a key to the Canadian species.—G. A. Bradley.
Effects of Trichoderma on Tree Seedlings and on
their Pathogens.—Several experiments have been made by
the author to explore the importance of Trichoderma species
in relation to tree seedlings. The results are summarized
here, although definite conclusions have not yet been reached.
However, the tentative conclusions may be of use since it is
likely that other workers are studying this interesting and
common soil fungus.
Preliminary experiments performed with various Finnish
tree species in quartz sand media suggested that Trichoderma
sp. might be pathogenic to heavily shaded seedlings. This
possibility was tested further by inoculating half-strength
potato dextrose agar in jars with a Finnish Trichoderma
strain, and sowing surface-sterilized seed of Pinus banksiana
Lamb. on the colonies. In addition to this Trichoderma
strain (F), suspected of being pathogenic, strains isolated
from a seedling of P. banksiana in Saskatchewan (S) and
from soil in Connecticut (C) were similarly tested. The
jars were kept under two different light intensities at 20°C.
The survival percentages were as follows:
P
C
S
20 41
25
11
450 65
66
56
Light, ft. c.
LSD •5
0.05
57608
The results indicate that Trichoderma strains are potentially pathogenic, especially under weak light, and that the
strains differ in their pathogenicity. These conclusions were
confirmed in other tests with these and other strains and with
seedlings of P. banksiana, P. sylvestris L., Betula pubescens
Ehr., B. lutea Michx. f., and Caragana arborescens Lam. on
various sterilized agar media.
To study the effects of Trichoderma on an important
pathogen the following experiment was conducted. Potato
dextrose agar plates were inoculated at one edge with a
Rhizoctonia solani Kuhn strain which has been proved strongly
virulent on various tree seedlings. The opposite edge was
inoculated with a strain of Trichoderma. Eleven strains of
Trichoderma were used in this manner. The tests were
repeated at three temperatures, 7, 15, and 25°C. All the
fungi grew well at these temperatures. Every strain of
Trichoderma reduced growth of R. solani antibiotically from
a distance of several centimetres. When Trichoderma colonies
contacted the R. solani colonies, these ceased to enlarge and
were overgrown by Trichoderma.
As a next step, Trichoderma was studied in certain soils.
Seedlings of P. banksiana were grown in pots in sterile and
non-sterile garden soils and in Sphagnum peat. Each soil
was heavily inoculated with spore suspensions of two Trichoderma strains. All combinations were replicated under three
slightly different light conditions. No significant effects were
detected. Rather than being pathogenic, Trichoderma appeared
to increase slightly the survival of the seedlings. In another
experiment Trichoderma strains were at first inoculated on
agar in jars. Soil was then poured on top of the colonies
and seeded with P. banksiana. This soil was sandy loam from
a nursery and was known to contain both R. solani and
Pythium ultimum Trow. The soil was either left in normal
state (N), amended by 2/100 malt syrup (M), by 1/3 lichen
powder (L), or autoclaved (A). The survival percentages in
three weeks were as follows:
N
Control Trichoderma (ay. of 3 strains) M
A
11
5
55
4
6
59
Neither pathogenicity nor biological control by any of
the Trichoderma strains could be demonstrated in this test.
The results were the same when Trichoderma was allowed to
invade the soil layer before the seeding was done. The high
mortality caused by Pythium and Rhizoctonia flora in all
non-autoclaved soils appeared to be slightly decreased by
the soil amendments. Further tests are being made with
other amendments to find if some may exert a worth-while
reduction of damping-off.
These studies demonstrated potential pathogenicity and
potential antagonism to other pathogens by Trichoderma, but
cast considerable doubt on the actual importance of either
action in certain soils. One explanation of this is that the
fairly phytotoxic and strongly antifungal antibiotics known
to be produced by Trichoderma may accumulate under certain
conditions but not under others. For instance, they may be
largely inactivated by fine particles of soil.-0. Vaartaja.
ROCKY MOUNTAIN REGION
LSD
0.01
=9
Relationships Between Site and Decay in Subalpine
Spruce in Alberta. —A systematic survey of the East Slope
Region of the Canadian Rockies was made in 1953 to examine
site factors in relation to root and butt infections of subalpine
spruce. The following is a report on a preliminary analysis
of the data.
G
The study was based on 53 sample plots established within
the spruce type in uncut stands representing a variety of site
and stand conditions. Records were made on elevation, aspect,
slope, and ground cover composition, and samples were taken
from the "B" horizon of the soil for laboratory determinations
of total nitrogen, pH, and texture. The depth of the Ao
horizon was measured. Basal infections were determined from
samples obtained with an increment borer from the base of
the trees. Infection ratings for each plot were determined
by calculating the ratio of infected spruce trees to the total
number of living spruce trees occurring on the plots. Usually,
the sample consisted of 10 spruce trees on each of the plots.
For the vegetation analysis, the plot data were first separated
into three distinctive geographical regions which were determined by watershed limits, and then arranged into two groups
of plots representing low (0 to 20%) and excessive (40% or
more) numbers of basally infected trees. The presence of
specific indicator plants on the plots in each infection class
was determined by using Braun-Blanquet's method for estimating the significance of plant indicators in plant associations. Depending upon the relative occurrence of low-infection
and high-infection indicator plants, the plots were then
separated into three site types each of which represented a
natural unit of vegetation; each presumably having a similar
environment.
Within each site type, the trees were arranged in age
classes and the incidence of infected trees was calculated for
each class. This analysis showed that the percentage of
infected trees increased with increasing age of the trees at
different .rates for the three sites. The average infection
values obtained for the three site classes were 12.1%, 222%
and 35.1%. This appraisal led to the conclusion that the
disease status of the site types could be designated I, II,
and III, thus providing site indexes for stands having low,
moderate, and high numbers of basally infected trees respectively.. At the advanced age of 270 years, only 15% of the
spruce trees that were examined on the class I sites were
infected, while all the trees of this age on the class III
sites possessed some basal rot. The sites also appeared to
be characterized by different rates of stand deterioration as
demonstrated by the different age structures in the groups.
Thus, the older age classes, viz, those in excess of 150 years,
contained 57% of the trees on the class I sites, 44% on the
class II sites, and only 37% on the class III sites.
Differences in the vegetation occurring between the low
infection and high infection sites appeared to reflect differences
in the moisture conditions, since indicator plants for the low
infection sites include such xerophytic plants commonly
associated with dry sites in Alberta as Juniperus canadensis,
Shepherdia canadensis, Arctostaphylos uva-ursi, Fragaria
glauca, and Pinus contorta. On this basis class I sites with
a low incidence of disease might be described as dry, and
the class III sites, where hydrophytic plants dominated, as
moist.
Observations also indicated the existence of a definite
link between the rate of diameter growth and susceptibility
to infection in the trees. There was a consistent increase in
the number of infections with an increasing width of the
annual rings. Using height as a criterion of growth, a similar
but less pronounced trend was obtained but this might be
attributed to the fact that average height values unlike the
average diameter values were not based on all the spruce
trees occurring on plots, but on one or two dominants.
Attention was next directed to the possibility of discovering if other criteria exist which demonstrate the ecological
distinctiveness of the pathological sites. The positive or
negative association of any particular site factor, e.g., high
or low nitrogen content of the soil, or high or low elevation,
with a particular site, was appraised by first separating the
plot data into two groups, each group representing one of
the two opposing effects to be tested. The data were then
arranged in 'contingency tables under the appropriate site
class designated for the plot. If a relationship was absent,
the observed frequency of plots falling into a particular site
class should approximate the calculated expectations, and the
resulting chi square value would be small. For example,
Table I shows how the frequencies for the plots from high
and low elevations are distributed among the three site classes.
' Initially an arbitrary altitude value defining the class
limits was employed and the value which gave the best
contingency chi square value was taken to represent the
critical value for the maximum environmental effect of the
factor on infection. In this case, an elevation of 4400 feet
above sea level gave a significant chi square value (P = .01).
The results of analysing the factors employing this method
are given in Table II.
The importance of such . physiographic features of sites
as elevation, aspect, and slope can be seen from these data.
Thus, stands of spruce which are located on a west, southwest,
or south slope having a gradient in excess of 15.5% at
altitudes below 4400 ft. above sea level, might be expected
to support more infected trees than stands which do not
have these features. There is also evidence that more infected
trees occurred on acid soils, i.e., pH 6, than on neutral or
alkaline soils. Most severely infected stands were associated
with soils characterized by a relatively thin humus layer.
D. E. Etheridge.
TABLE I
Frequencies
Altitude
(ft. above sea level)
Site I
Obs.
Site II
Cal.
Obs.
Site III
Cal.
Obs.
Cal.
Below 4400 0
5.4
7
4.2
8
5.4
Above 4400 19
13.6
8
10.8
11
13.6
Totals 19
19
15
15
19
19
Nom—Total chi square =11.886, P= .01
TABLE II
Site factors having a
positive influence on
the rate of infection
Sample
basis
Contingency chi
square,
Probability
West, southwest 23
Aspect W. SW. S 52
7.371
6.475
< . 05
> .02
Altitude Below 4400 ft 53
11.886
< 14.5 per cent 53
14.173
53
0.132
Not sig.
47
6.157
> .02
53
0.043 to
2.240
53
6.420
< .05
> .02
Aspect Slope Soil texture Critical
level
Light vs. heavy Depth of humus (As). < 1.75 ins Soil nitrogen (total)..
Soil pH Over range 0.100% to
0.140% < 5.95 .01
.001
G .05
Not sig.
Degree of windfall...
Light vs. heavy 42
1.990
Not sig.
Site indexes.
I (dry) II (Intermediate)...
Incidence of infs 0-20% 21-40% 53
53
22.839
.001
III (Moist) >-40% 53
1 Degree of freedom=2, except for the site index item which is 4.
BRITISH COLUMBIA
A study of the Effect of Nematodes and Mites on
Douglas-fir Beetle Flight.—The effect of nematodes and
mites on the flight capacity and response to ffight stimulation
of the Douglas-fir beetle, Denroctonus pseudo tsugae Hopk.,
was tested as a step in an investigation of the insect's flight
behaviour. Two experiments were carried out, the first to
determine the effect of mites and nematodes on response to
flight stimulation and the second to determine their effect
on the beetles' flight capacity. The insects used in the experiments were young adults collected within one day of emergence from logs overwintered near Lumby, B.C.
One hundred and twenty beetles were subjected to a
flight stimulus, immediately after capture, by tossing each
individual into the air in a room with one unshaded window.
After each beetle had been tossed three times it was placed
in one of four categories of response. Two responses, good
and poor flight were considered positive, while the other
two, fluttering and merely opening the elytra were considered
negative.
Following the flight stimulation tests, each beetle was
dissected to observe the gut condition. (full or empty), sex,
and the presence or absence of mites and internal and external
nematodes. The results of this test are condensed in Table I.
To date, identifications indicate that there are at least
seven species of nematodes, belonging to five genera, which
are directly associated with the Douglas-fir beetle. Due to
the complexity of the nematode larval stages, the lack of
knowledge on their relation to the host, and the difficulty of
identification, it has not been possible to determine which
of these round worms is the most important. Because it
was impractical to count any other than the adult stage due
to occurrence of high numbers, relative expressions were used.
If the majority of these nematodes are true parasites,
one would expect the internal species to be in the most
favourable position to be a drain on the beetles' metabolic
reserves and thus have the greatest effect on the beetles'
At the completion of the tests each individual was dissected
and observations made as in the first experiment. Only four
beetles had mites so their effect was disregarded.
Student's "t" test was used to compare the mean flying
times of the uninfested males and females, and showed no
significant difference. The mean flying time of all uninfested
beetles was then used as a basis for comparison of the various
degrees of infestation (internal nematodes only, external
nematodes only, both internal and external nematodes, and
internal nematodes regardless of infestation by external forms).
There was no significant difference in any of the comparisons.
The means, degrees of freedom and "t" values are given in
Table II.
condition. However, it was noted that 12 of 87 beetles
recorded as having good response had numerous internal
nematodes and 13 of 22 beetles with a negative response
had no internal nematodes.
The mites were external in all but two cases. Most were
six-legged immature forms under the elytra.
In the second experiment, samples of beetles showing a
strong flight response, as indicated by tossing, were attached
to individual flight mills described by Chapman (Forest
Biology Laboratory, Victoria, B.C., Interim Report. 1954).
Thirty beetles were flown for a 4-hour period. As most of
the beetles tended to fly intermittently the starting and
stopping times were recorded and the flying time totalized.
TABLE I
FLIGHT RESPONSE AND DISSECTION RESULTS OF 120 DOUGLAS-FIR BEETLES
Positive Negative Total Nematodes
Sex
Gut con'dition
Response
Male
Female
98
7
91
30
68
6
1
20
1
4
2
24
22
3
19
8
14
0
120
10
110
38
82
6
Comparison and infestation
Mean flying
time
Uninfested males d.f.
156.7 min.
...
147.4
152
"
.0016
min.
-• 1 External nematodes only 152
17
2 Internal nematodes only 148
13
.0913
3 Internal and external nematodes 181
12
.9500
4 Internal nematodes* 163
28
.4570
CI
.0000
*Any beetles with internal nematodes regardless of external forms.
The first test indicates that the presence of mites and
nematodes has no significant effect on the flight response of
the insect immediately following emergence. The second
test indicates the nematodes do not affect flight duration at
this time.—M. D. Atkins.
Dieback of Douglas Fir.—Damage to the leaders and
laterals on reproduction and sapling-sized (under 35 feet tall)
Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) was noted
in the spring of 1956. An examination of young stands in
widely separated regions showed the damage to be general
and restricted to Douglas fir. Although light damage, under
1 to 2 per cent incidence of dead leaders, was found in most
areas, moderate damage was noted near Salmon River in both
natural regeneration and plantations, and severe damage near
Sooke in natural regeneration. Sample plot analysis showed
that dead leaders averaged 22 per cent and 52 per cent in
damaged areas at Salmon River and Sooke respectively.
Both areas of concentrated damage were on exposed dry
slopes underlain with deep gravel which lacked ground water
during the growing season. Despite this dryness Douglas fir
was making good height growth. In the other areas examined
the disorder appeared to occur on a random basis and was not
correlated with exposure, elevation, or aspect. Frequently
those areas with the best height growth had dieback damage.
A severe cold period, with dry air and strong winds
which began on November 11, 1955, suddenly terminating a
previous moist mild period, is believed to have caused the
damage noted.
The dieback was evidenced by a yellowing, reddening,
and then a thinning or loss of needles, followed by cracking
of the bark and dying of the 1955 leader or top laterals.
In the fall of 1956 there was extensive callusing and bark
splitting at the juncture of the killed and healthy tissue.
Side branches at and between whorls were observed to turn
yellow and die. At Sooke, in addition to the above damage
and frequently on the same trees, although not necessarily
associated with the same fungi, there were trunk cankers at
Mites
only
Mites
and
Nematodes
23
6
54
7
2
14
30
8.
External Internal and
only
External
Empty
TABLE II
Total uninfested vs Internal
only
Full
ANALYSIS OF TOTAL FLYING TIMES IN 4-HOUR PERIOD OF 30 DOUGLAS-FIR
BEETLES WITH VARIOUS DEGREES OF INFESTATION
Uninfested females No. Parasites
Total
68
the juncture of branch and trunk. These cankers enlarged
throughout the summer to girdle the bark, and killed the
distal portion of the tree. Resinosis was generally absent
except where the Douglas-fir bark beetle (Dendroctonus pseudotsugae Hopk.) was active.
Progressive dying in successively older branch whorls was
observed at Sooke as the fungi which entered through the
weakened or dead tops moved down the sapwood of the
trunk. Some trees with this type of infection have already
died. Trees have also been killed by trunk cankers. Resin
soaking observed in the new springwood has not halted the
lateral spread of fungi in the trunk. Where the tip of a
leader is killed, and one lateral shows dominance, the spike
of dead sapwood provides an entrance court for decayproducing fungi.
The most frequently isolated fungi from damaged leaders
have been Pullularia sp., and Phomopsis sp. From the trunk
cankers, Dasyscyphus sp., and Stereum sanguinolentum (Alb. &
Schw. ex Fr.) Fr. have been isolated. These fungi have all
been recorded previously as weakly parasitic under conditions
of host injury or weakening. Inoculations are in progress in
both field and greenhouse to test the pathogenicity of these
fungi. Douglas-fir seedlings weakened by cold and by drought
as well as healthy plants have been inoculated.
The possibility that those trees which flush earliest in
the spring may be the last to harden in the fall and may
be more susceptible to early frost than adjacent late-flushing
trees is being investigated.
While leader diebacks have in the past caused only
limited damage, it is noteworthy that following unusually low
temperatures in 1955, extensive damage and mortality have
been observed in localized areas. Genetic differences between
individual trees would contribute in part to the random
distribution of this damage. While this damage cannot be
specifically related to the cold period, it probably results
from it. The effect of this environmental condition on both
the host and on the normal fungi of the area remains
unknown.--W. A. Porter.
The Spruce Budworm Infestation in the Lillooet and
Fraser River Areas.—The spruce budworm infestation in
the Lillooet and Fraser River areas was first reported in
1953, and has been under close observation since 1954. The
principal host is Douglas fir. In 1954 the outbreak was
restricted to the Lillooet River and Lake area, and a smaller
area in the Nahatlatch-Fraser river valleys (G. T. Silver and
M. G. Thomson, Bi-Mon. Progr. Rept. 10(5) : 2-3. 1954).
The infestation has increased in size, and in 1957 extended
along the Lillooet River and Lake, westward as far as Tisdall,
northeast from Pemberton to D'Arcy, along the Anderson
and Seton lakes to Lillooet and down the west side of the
Fraser River Valley as far as Askom Mountain. The area
of the outbreak in 1957 was calculated at 498 square miles
compared with 452 square miles in 1956 and 379 square miles
in 1955. The area for 1957 does not include the Anderson
or Nahatlatch River valleys where the outbreak has subsided,
nor a small area near Pavilion Mountain where spruce
budworm populations increased considerably this year but
defoliation was too light to map.
In 1955, stands along the Lillooet River suffered heavy
defoliation and shoot damage. Some trees had all their buds
killed the previous year, and new growth was restricted to
adventitious buds. A good growing season in 1956, along
with reduced defoliation, resulted in a general improvement
in stand conditions. In 1957 defoliation of current foliage
along the lower Lillooet River was 64 per cent and total
defoliation now stands at 58 per cent. Stands in the vicinity
of Pemberton, which had been damaged heavily in 1954 and
1955, suffered little or no defoliation in 1957. Consequently,
many trees which had been expected to die are recovering,
and many tree tops which had been completely stripped are
putting out new growth. Top kill and probably scattered
tree mortality may occur throughout portions of the outbreak
area, but the general stand condition is good.
Defoliation along Anderson and Seton lakes was heavy
in 1956 and 1957, but back feeding has not been severe and
shoot mortality is light. These stands are in relatively good
condition and have not suffered damage to the same extent
that the recovering trees around Pemberton sustained in 1954
and 1955.
The infestation in the Nahatlatch River Valley has
subsided and defoliation was relatively light in the Anderson
River Valley in 1957.
The percentage of egg masses containing parasites
remained low throughout the outbreak. Pupal parasitism
varied from 35 to 60 per cent and larval mortality due to
parasites was light to medium. No virus disease of any
consequence has been encountered in any area.
The spruce budworm population, as indicated by egg
counts, has decreased steadily in the Lillooet River and
Lake area (Table I). The figures shown are averages and
the range is large, i.e., 0 to 151 egg masses per 100 square
feet of foliage surface in 1957. Egg populations in the other
areas never reached the large numbers obtained in the older
portion of the outbreak. There was an average decrease of
about 60 per cent in the egg population in all areas in 1957
compared with 1956.
TABLE I
AVERAGE NUMBER OF SPRUCE BUDWORM EGG MASSES PER 100 SQUARE FEET
OF FOLIAGE SURFACE
Area
Lillooet River and Lake 1954
1955
1956
1957
221
112
64
31
Tisdall-Nairn Falls Pemberton to D'Arcy 39
75
15
46
20
157
41
Fraser River 99
21
Nahatlatch-Anderson River valleys. 30
9
Anderson and Seton Lakes EDMOND CLOUTIER, C.M.G., O.A., D.S.P.,
•
H
The spruce budworm population is expected to continue
its downward trend. There are still localized pockets in which
the egg population is sufficiently high to cause heavy defoliation in 1958, but these represent only a small proportion of
the total area.-G. T. Silver.
RECENT PUBLICATIONS
Anonymous. Dutch elm disease. Pub. 1010 Can. Dept. Agr.
1957.
Bird, F. T. and Elgee, D. E. A virus disease and introduced
parasites as factors controlling the European spruce sawfly,
Diprion hercyniae (Htg.), in central New Brunswick.
Can. Ent. 89: 371-378. 1957.
Buckland, D. C., Redmond, D. R., and Pomerleau, R. Definitions of terms in forest and shade tree diseases. Can.
J. Bot. 35: 675-679. 1957.
Engelhardt, N. T. Pathological deterioration of looper-killed
western hemlock on southern Vancouver Island. Forest.
Science 3: 125-136. 1957.
Etheridge, D. E. Comparative studies of Coryne sarcoides
(Jacq.) Tul. and two species of wood-destroying fungi.
Can. J. Bot. 35: 595-603. 1957.
Faulkner, P. and Bergold, G. H. Deoxyribonuclease content
of an insect virus. Virology 3: 603-605. 1957.
Foster, R. E. Pole blight of western white pine. Timber of
Canada 18 (9) : 60, 62, 63, 65, 66, 100. 1957.
Ghent, A. W., Fraser, D. A., and Thomas, J. B. Studies of
regeneration in forest stands devastated by the spruce
budworm. I Evidence of trends in forest succession
during the first decade following budworm devastation.
Forest Science 3: 184-208. 1957.
Green, G. W., Baldwin, W. F., and Sullivan, C. R. The use
of radioactive cobalt in studies of the dispersal of adult
females of the European pine shoot moth, Rhyacionia
buoliana (Schiff.). Can. Ent. 89: 379-383. 1957.
Greenidge, K. N. H. Ascent o f sap. Ann. Rev. Plant Physiology. 8: 237-256. 1957.
Harvey, G. T. The occurrence and nature of diapause-free
development in the spruce budworm, Choristoneura fumiferana (Clem.). Can. J. Zool. 35: 549-572. 1957.
McKeen, D. C. and McGugan, B. M. A general review of
plant protection organization in Canada. (Paper presented at Seventh British Commonwealth Forestry Conference, Australia and New Zealand, 1957). Processed,
Can. Dept. Agr. 1957.
Peterson, L. O. T. The control of the pine needle scale in
the Prairie Provinces. Pub. 1018 Can. Dept. Agr. 1957.
Smith, D. N. Carpenter ant infestation and its control.
Pub. 1013 Can. Dept. Agr. 1957.
Queen's Printer and Controller of Stationery. Ottawa, 1957.
CANADA
DEPARTMENT OF AGRICULTURE
SCIENCE SERVICE-FOREST BIOLOGY DIVISION
Vol. 13
REPORT
Number 6
BI-MONTHLY PROGRESS REPORT
Nov.-Dec.
1957
Published by Authority of the Hon. Douglas S. Harkness, Minister of Agriculture, Ottawa
CURRENT ACTIVITIES
ATLANTIC PROVINCES
Occurrence of Ceratocystis ulmi (Buism.) C. Moreau
in New Brunswick. —On November 21, 1957, it was definitely
established that the causal fungus of Dutch elm disease had
been obtained in culture from elm bark collected from one
tree at Woodstock, N.B. during October. Although the
advent of this disease in New Brunswick has been anticipated
for some time this is the first known occurrence in that
Province. It is not known how it may have been introduced.
The nearest known cases of Dutch elm disease are about
55 miles distant in the State of Maine. Arrangements were
immediately made to have the infected tree destroyed. At
this time of the year, it is not practicable to carry on surveys
for this disease but the Forest Biology and Plant Protection
Divisions are co-operating in planning the work which must
be undertaken next year.
ONTARIO
Comments on the Agents Responsible for the Cankering and Killing of Balsam Fir in Eastern Canada.—
A pathological condition which has existed in balsam fir
throughout eastern Canada for many years is manifested by
the dying of branches, tops, and entire trees. It is accompanied by a striking - and characteristic reddening of the
needles and usually by a cankering at the base of the affected
portion. Causes have been attributed by entomologists to
the feeding of adult sawyer beetles and of woolly-aphid larvae
and by pathologists to attack by one or another nominally
saprophytic fungus. None of these reputed agents is, however,
acceptable by itself as a causal organism. On the other hand,
a comprehensive theory which has been evolved and which
is being successfully tested, is considered to explain satisfactorily the dieback "disease" without necessarily rejecting
any of the earlier theories. These are held to be incomplete
rather than incorrect. Several fungi are believed capable of
causing the "disease", but only when insect attacks or mechanical injuries provide them with means of entry into the trees.
One such fungus, Thyronectria balsamea (Cke. & Pk.)
Seeler, which has been both widespread and abundant throughout Ontario for at least the last three years, has been proved
capable of rapidly producing typical symptoms if introduced
into surface injuries to twigs and stems. However, even with
massive inoculation, it is only rarely able to enter intact
tissue, and no symptoms have resulted from uninoculated
injuries in any of 69 cases involving 14 young trees.
Two other fungi, Dermea balsamea (Pk.) Seay. and
Cytospora sp., which are also associated with typical cankering
and dieback, were found in 1957 to be nearly as widely
distributed as Thyronectria, and in some cases to be even
more abundant. They are currently being tested. A fourth
putative canker-producer was found too recently to have
been identified, and others may exist in Ontario at the present
time. In the Maritime Provinces, Fusicoccum abietinum
Prill. & Delacr. and Valsa friesii Duby have been reported
recently in association with cankering of balsam (cf. Ann.
Rept. of the Forest Insect and Disease Survey, 1956). The
Valsa may be the perfect stage of the Ontario Cytospora.
On the insect side, proof is not yet as complete, but all
of the evidence strongly supports the belief that various
insects provide entry to the fungi by injuring the trees, carry
inoculum to uninfected wounds, or both puncture and inoculate
the trees.
In the case of the sawyer beetle (Monochamus spp.), for
example, the writers had found the characteristic feeding
scars of the adults to be commonly associated with typical
dieback in every area visited for two seasons before they
were aware that the injuries were caused by an insect. Angus
Harnden, Forest Biology Ranger in the North Bay District,
identified the nature of the scars immediately upon seeing
them.
Isolations from twigs in which death was associated with
Monochamus feeding have, on different occasions, produced
87610
Thyronectria, Dermea, and Cytospora. Furthermore, all three
fungi tend to fruit abundantly and extensively on the smooth
younger bark of dead trees when moisture is adequate, so it is
likely that in many small trees the emerging beetles would
immediately come into contact with fruiting bodies and their
sticky spore-masses. The ability of beetles to inoculate
wounds they cause or to produce symptoms without inoculation
will be tested when they become available next spring.
That insect activities can stimulate hypertrophies in trees
is well known. In the Maritimes, Balch (Studies of the
Balsam Woolly Aphid, Adelges Piceae (Ratz.) and its Effects
on Balsam Fir, Abies Balsamea (L.) Mill., Can. Dept. Agr.
Pub. 867, 1952) showed that the feeding of woolly-aphid larvae
caused "gout" disease and the slow dying of balsam which
he attributed to a combination of factors particularly
unfavourable to the trees. Opposing this interpretation is
the fact that similar feeding on another host (cf. Haddow
and Newman, A Disease of the Scots Pine caused by Diplodia
pinea associated with the Pine Spittle-Bug, Trans. Roy. Can,
Inst. 24(1) 1-17, 1942) was shown to result in disease symptoms only when the fungus was present. Balch, incidentally,
reported the sporadic presence of Creonectria cucurbitula, h
name which is synonymous with T. balsamea. In this connection, it should be pointed out that the fungi may fruit
at the end of one season in the host or not until the following
year.
Dying of foliage has also been observed in association
with the empty galls of a needle midge (Itonida balsamicola
(Lint.)) and with persistent cone-axils in some trees. This
latter case suggests that puncture of intact cones by some
insect such as the seed chalcid (Megastigmus) may constitute
sufficient wounding to permit entry by a fungus.
Logging operations, road building, and other such treedisturbing activities are very frequently followed by local
upsurges in balsam dieback. They are accompanied, usually,
by some damage to residual trees and, not infrequently, by
residues of slash suitable for the reproduction of Monochamus.
Mechanical injuries and uninoculated wounds caused by
biological agents may very well become infected through the
wandering about of non-injurious insects.
The only measure of defence from this "disease" which
immediately suggests itself is sanitation by proper and prompt
P
slash disposal in connection with woods operations.—F. L.
Raymond and J. Reid.
A Fungus Associated with Blight and Dieback of
Hybrid Aspen. —Throughout Ontario the progeny of Populus
alba L. X grandidentata Mich. are severely attacked by a
blight and dieback. This condition, with which an unidentified
species of Gloeosporium is consistently associated, has not
been observed on either parent. The importance of this
disease is heightened by the economic potential of certain
hybrid clones of this cross.
Disease symptoms appear in midsummer and consist of
under-development, discoloration, curling, and necrosis of
peripheral leaves on sporadic branches throughout the crown.
Regeneration and larger trees seem to be equally affected.
Orange "flags", clumps of diseased but still living leaves,
clearly indicate the affected branches. Dead leaves acquire
a deep chocolate-brown colour.
Although, in general, the symptoms suggest that the
disease is caused by adverse physiological processes, large'
numbers of minute apothecia on the upper surface of wet,
dead leaves are visible under moderate magnification. The
apothecia, occurring between epidermis and cuticle, contain
numerous, unbranched conidiophores each bearing a
single hyaline, oval conidium with average dimensions of
7.Oµ X 3.3u (4.1 — 10.7µ X 2.5 — 4.9g). Wide hyphae occur
within the cells of epidermal, palisade, and mesophyll tissues.
The intracellular occurrence of the mycelium and the fact
that disease symptoms appear only after foliar growth of
the host is well advanced suggests that the fungus is a
highly specialized parasite and the most probable cause of
the blight on these hybrids. In September, perithecial initials
are detectable in the mesophyll of dead leaves but the asci
do not mature until the following May. The identity of this
ascomycete is tentatively taken to be Gnomonia.
Different clones exhibited different degrees of susceptibility to this disease; hence, the prospect of overcoming this
blight appears to be favourable.-B. W. Dance.
PRAIRIE PROVINCES
Partial Breakage of Dormancy in Birch Seeds by
Gibberellin.-The combined effect of darkness and low
temperature (below 20°C.) is known to inhibit the germination
of non-stratified seed of certain species of Betula. Several
chemicals have been tried to overcome such dormancy. The
results so far have been negative with one exception. This is
gibberellin which recently has shown various growth stimulating effects in many experiments.
The gibberellin used was potassium salt of gibberellic
acid, manufactured by Merck Co. with the trade name Gibrel.
This salt was incorporated at various concentrations in the
germination media of 1 per cent agar in tap water in petri
dishes. Tersan 75 fungicide was also added at 50 p.p.m. to
suppress any fungal growth. The dishes were sown with seed
of white birch (B. papyrifera Marsh.) and water birch
(B. occidentalis Hook.). The seeds were kept in darkness
at 13°C. for 10 weeks, after which the germination was
recorded. Then the dishes were transferred under lights at
room temperature where the germination was completed in
1 to 2 weeks. The following table shows the percentages of
the germination that took place in darkness at 13°C. with
various concentrations of gibberellin (p.p.m.) :
250
B. papyrifera B. occidentalis 50
25
5
2.5
0.5
.12
In mid July and August, control tests were undertaken
by the Entomology Section, Forest Nursery Station, Indian
Head. Lime sulphur and malathion emulsion were applied as
foliar sprays against the nymphs. The treatments made and
the observations recorded are shown in the following summary. `Per cent mortality', was calculated, using Abbott's
formula (Abbott, W. S.-A method of computing the Effectiveness of an Insecticide. Jour. Econ. Ent. 18: 265-267:
1925).-Lloyd O. T. Peterson, Forest Nursery Station, Experimental Farms Service, Indian Head, Sask.
INSECTICIDE FORMULATION AND AMOUNT PER 100 GALLONS WATER
Check
(Unsprayed)
15
1194
92.0
10
1559
64.9
29.4
15
1365
7,8
91.5
12
1397
1.4
98.5
July 23
Leaves examined Scales present Per cent alive Per cent mortality 13
1947
92.7
10
2895
83.1
10.4
20
1005
2.5
97.3
10
1046
18.1
80.5
July 31
Leaves examined Scales present Per cent alive Per cent mortality 22
1079
86.5
11
1091
71.2
17.7
22
1255
12.9
85.1
18
1282
15.8
81.7
Date of treatment
August 19
12
4144
92.9
Leaves examined Scales present Per cent alive Per cent mortality 6
1488
58.8
4
6
0
2
0
0
0
83
50
33
32
38
20
11
The concentration of gibberellin was not critical. This
has been found in other studies with this chemical, and is in
contrast to the effects of auxins, which are toxic at high
concentrations. Search in the extensive literature concerning
effects of chemicals on seed germination revealed only one
result comparable to the 85 per cent increase for B. occidentalis
with gibberellin at 250 p.p.m. This result was obtained with
gibberellin and lettuce seed. Various other chemicals, e.g.
thiourea and related compounds, have been reported to
stimulate germination, but only to a much less degree than
above. Germination of 'birch and lettuce seeds can also be
stimulated with red light, but the physiology of this phenomenon is not known. The analogical stimulation with a
Chemical may help to discover the nature of the stimulation
with light.-0. Vaartaja.
The Brown Elm Scale, Lecanium. corni Bouché.This scale was very abundant on American elm trees in
Regina, Sask., during the 1957 season. It had been present
in the city for many years previously but only in insignificant
numbers. The scale overwintered as partly-grown nymphs
under loose bark and in crevices on the branches and trunks.
Winter survival was high as the nymphs were present in great
masses in the spring. It is possible that the above-normal
temperatures during the winter of 1956-1957 may have increased
survival. This scale occurred also on green ash and on Manitoba maple, but only in relatively small numbers.
By April 4 many of the hibernating nymphs were active
and in the process of establishing themselves on the smaller
branches and twigs; by early May many were becoming full
grown. Population density counts yielded approximately 10
living scales per linear inch of twig. By June 6 approximately
10 per cent of the females had laid some eggs and already
the twigs and branches were wet, sticky, and darkly discoloured
with the secretion from the females. Hatching began in early
July and was completed before July 18. By late July a new
generation of nymphs had moved to the leaves. Many individuals were already large, flattened, and lime-yellow in colour.
The remainder were small and dark yellow in colour; some
of these were still moving about actively. In the samples
taken on the foliage and totalling more than 25,000 scales,
90 per cent of the population was found on the lower surface
of the leaves. Parasitism of the scale occurred but was not
appraised.
Because of the abundance of the brown elm scale, the
unsightliness of the infested elm trees, and the damage which
the scale seemed to be causing to the smaller branches and
twigs, chemical control was attempted by the Regina City
Parks Department. In early May, after the overwintered
nymphs were established on the twigs but before the leaves
had developed, a spray containing two pints of malathion
50 per cent emulsion per 100 gallons of water was applied
to the trunks and branches. This treatment proved ineffective.
4p
Leaves examined Scales present Per cent alive Per cent mortality Leaves examined Scales present Per cent alive 13
2 pt.
Date
examined
Date of treatment
July 18
0
96
Malathion
50%
emulsion
Dry
lime
sulphur
8.3 lbs.
August 19
6
897
33.6
42.8
10
1057
4.3
92.7
6
1296
1.0
98.3
September 9
ROCKY MOUNTAIN REGION
Correction.-In Vol. 13 No. 5, page 2, top line of
column 2, "15.5%" should be "14.5%". Also in Table II in
same column, "<14.5 per cent" should be ">14.5 per cent".
ROCKY MOUNTAIN REGION
Antagonism by Coryne sarcoides (Jacq.) Tul.- Recent
preliminary studies have indicated that certain strains of
Coryne sarcoides, a non-decay-producing ascomycetous fungus,
are antagonistic to wood-destroying fungi on malt agar and
on wood. Because of the wide-spread occurrence of this
fungus on living conifers and its frequent association with
heartrot fungi, it was of interest to determine the incidence
of actively antagonistic strains in a larger sample.
A total of 79 isolates of this fungus were screened for
the occurrence of strains antagonistic to Coniophora puteana
(Schum. ex Fr.) Karst., a brown rot fungus, and Peniophra
septentrionalis Laurila, a white rot fungus. These isolates
comprised 21 from lodgepole pine, 49 from white spruce, and
1 from balsam fir. in Canada, together with 8 isolates from
various hosts in Britain. The tests were carried out by placing
an agar plug from an actively growing culture of the wooddestroying fungus at -one edge of a petri dish containing
20 ml. of 2% malt extract agar. A spore suspension of
C. sarcoides was streaked on the opposite side of the plate
at a distance of about 6 cm. Observations were made on the
mutual effects of the growth of the two colonies at the end
of 1, 2, 3, and 4 weeks. Table I records the interaction of
the fungi after 4 weeks. The interaction was determined by
the ability of various strains of C. sarcoides to inhibit the
growth of the wood-destroying fungi at the point of contact
of the colonies.
TABLE I
ANTAGONISTIC ACTIVITY of Coryne sarcoides
Origin of Isolates
No. of
isolates
Antagonism
Against C. puteana
Against
P. septentrionalis
No.
%a
No.
Canadian Isolates 71
8
11.3
27
38.0
Lodgepole pine 21
2
9.5
21
100.0
White spruce 49
5
10.2
5
10.2
1
100.0
1
100.0
8
7
87.5
7
87.5
79
15
19.0
34
43.0
Balsam fir British Isolates Totals These results largely agree with those of a previous
investigation when tests were made with fewer isolates.
The highest number of active strains occurred among the
British isolates which were equally effective against both the
white and brown rot fungus. It is noteworthy that all the
Canadian isolates of C. sarcoides which came from lodgepole
pine were effective against P. septentrionalis, a fungus which
is unknown on living lodgepole pine but which frequently
occurs on white spruce.
The results indicate that there is extreme variability in
antagonism among isolates of this fungus, and that there can
be specificity in the inhibitory action against certain fungi.
Although the fungus appears unlikely to assume importance
as a factor in the development of decay because of the
relatively limited occurrence of active strains, the knowledge
that such interactions may occur between fungi in the heartwood should contribute to a better understanding of factors
that determine fungal succession in trees.—D. E. Etheridge
and Elizabeth Carmichael.
BRITISH COLUMBIA
A Comparison of Insect Species on Pole Blighted and
Healthy Western White Pine, Pinus monticola Dougl:
During the summer of 1956 a study was carried out on white
pine in the Arrow Lakes and Slocan Lake region of the
Nelson Forest District of British Columbia. The object was
to find o ut what insect species were associated with pole
blighted and healthy white pine trees.
Eighteen healthy and 18 pole blighted trees were selected
for sampling in four different plots. In each of three pole
blighted areas, Makinson Flats, Fosthall, and Silverton, six
pole blighted trees and three healthy trees were selected;
in one non-affected area, Caribou Creek, nine healthy trees
were selected. Samples, each consisting of four foliage-bearing
twigs, were taken from each tree at upper-, mid-, and lowercrown levels. Four samples were taken at each level making
a total of 12 samples per tree. Each foliage sample was
placed in a paper bag and examined in the laboratory for
insects. The bark was also examined for insects when foliage
samples were taken. Sampling was carried out (1) May 23
to June 29, (2) July 6 to August 1, (3) August 9 to
September 10. Where regeneration trees were growing near
the plots, beating samples were taken. Root crowns of all
sample trees were exposed and examined for insects and insect
damage.
The average number of insects from foliage samples per
pole blighted tree totalled for the three samplings ranged
from 52 in the plot at Silverton to 83 in the Fosthall plot.
The average per tree for all pole blighted trees was 67.
Root examinations showed that seven of the 18 sample
pole blighted trees were damaged by Hylobius larvae. Damage
was not severe in any of the root crowns and was usually
restricted to cambial damage in root crotches; no root crowns
were completely girdled.
The average number of insects collected per healthy tree
ranged from 48 at Caribou Creek to 83 at Fosthall. The
average for all healthy trees was 66.
Root crowns of healthy trees were damaged by Hylobius
in the same ratio as pole blighted trees, i.e., seven infested
to eleven uninfested. Fifty-three other healthy trees ranging
in size from 0.5 in. to 20 in. D.B.H. were examined for
damage to root crowns. Fifteen of these trees suffered
damage from Hylobius ranging from slight to severe. The
severe cases were small trees which had their root crowns
completely girdled.
Ninety species of insects and mites were taken from
white pine trees. Forty-two of these occurred on pole
blighted trees, 46 on healthy trees in areas affected with pole
blight, and 36 on healthy trees in unaffected areas. Nineteen
species were found only on pole blighted trees, 18 only on
healthy trees in affected areas, and 21 only on healthy trees
in unaffected areas. Six species occurred in all three
categories.
The data obtained do not provide conclusive evidence
on the extent to which insects and mites are responsible for
or associated with the pole blight condition. A comparison
of the number and kind of insects and mites occurring on
pole blighted trees with unaffected trees and areas suggests
that they do not contribute directly to the condition by
their feeding activities. Some of the species found only on
pole blighted trees or in pole blighted areas might conceivably be linked with the condition as vectors. however,
further study at this time of the invertebrate fauna in relation
to this problem is not likely to yield information that will
contribute to its solution.—A. F. Hedlin.
A preliminary Study of the Deposition and Early
Growth of Fungus within the Galleries of the Ambrosia
Beetle Trypodendron lineatum (Olio.). —Recently, the
means by which certain ambrosia beetles, including T. lineatum, carry the spores of their fungus from one gallery to
another, and the location of dermal glands associated with
fungus transport, have been described by Francke-Grosmann
(Z. Morph. u. Okol. Tiere, 45: 275-308. 1956). There are.
however, several aspects of the initial deposit and growth
of ambrosia fungus which remain to be clarified. A study
of the location and nature of early fungus deposits in developing galleries of T. lineatum was started at the Victoria
Laboratory in the spring of 1957.
A. portion of a Douglas-fir log attacked by beetles April
28 and 29 was brought into the Laboratory and blocks containing developing galleries were cut out at 9-, 12-, 16-, and
33-day intervals. The blocks were fixed in FAA (FormalinAceto-Alcohol) solution, using reduced pressure, and 40 micron
transverse sections cut through the galleries. The sections
were stained with 1 per cent aqueous Safranin, counter-stained
with saturated Picro-anilin blue and mounted.
A study of slides representing 18 galleries revealed the
following picture. Nine-day galleries showed a completed
vertical or radial entrance portion and the start of both
horizontal branches, the longest of which was 11 mm. in length.
Small clumps (one to seven per section) of blue-staining
material, containing spore-like structures identical in appearance with those taken from the prothoracic dermal glands
of Trypodendron were found on the gallery walls at irregular
intervals. This material was often packed into wood cells
(almost exclusively spring wood) which had been opened
during gallery construction.
In 12-day galleries the small fungus deposits were more
frequently found. They occurred only occasionally in the
vertical portion of the gallery, being far more common in the
two horizontal branches. Some of the fungus cells had started
to elongate and grow, and slight aerial extensions into the
gallery occurred. Also, some growth of hyphae into the wood
was in evidence.
In 16-day galleries the fungus had definitely started to
spread along the walls, although there was still much of the
wood surface not overgrown. Fungus hyphae had penetrated
as much as two or three cell thicknesses into the wood, Wood
cells in which the fungus was originally packed were full of
hyphae but these had not yet penetrated the thicker cell
walls of the summer wood. The fungus growth, coloured
entirely blue in previous stages, was now partly reddish-brown.
The 33-day galleries, in which the longest horizontal
branches were over 32 mm. in length, showed an almost continuous lining of fungus, including ;much of the radial entrance
portion. The hyphae had penetrated both spring and summer
wood cells profusely. The older fungus appeared black to
muddy brown in colour although younger growth was still blue.
The above observations indicate that the ambrosia fungus
is deposited by T. lineatum at a number of scattered points
within a gallery during its construction. This fungus thus
has a good opportunity to become established quickly. The
presence of many initial deposits of fungus in open wood
cells, their occurrence with much greater frequency in the
branches than in the entrance portion ,of the gallery, and
their apparent increase in number in parts of the gallery
already excavated, all suggest that the deposition process may
be under control of the beetles and not due merely to the
physical exertion of burrowing.—S. H. Farris and J. A. Chapman.
A Case of Nematode Infection in the Western Tent
Caterpillar.—Reports of parasitism of Lepidoptera by nematodes are rare. The only record to come to the authors'
attention was of a late-instar larva of Malacosoma pluviale
Dyar in the summer of 1955. This larva was one of two
live and four dead specimens collected at Toba River, about
45 miles north of Powell River, B.C., which were submitted
for disease diagnosis. Two live larvae were placed in a
rearing container with suitable food. Six days later both
larvae were dead and one of them had what appeared to
be several extraordinarily long nematodes extending in a
coiled fashion from a hole in the integument. In all, four
nematodes were extracted from this one location on the body.
They were easily removed intact by means of forceps. No
worms were recovered from other regions of the body cavity
or in the other specimens of the same collection.
The nematodes were identified by Dr. M. A. Khan as
larvae of the family Mermithidae. They are long, slender,
and cream coloured, with no obvious external or internal
morphological features. They vary in length from 13.5 to
16.0 centimetres. The average width of the mid region of
the body is about 0.5 mm.
Nematode infections in M. pluviale, or other forest
Lepidoptera, do not appear to be important biological control
agents judging from the extremely low incidence of their
occurrence. While rarity of cases makes records such as the
above noteworthy, these parasites should also be regarded
as potential sources of interesting and profitable investigation.—S. M. Sager and M. J. Bassett.
Heavy Damage to Chinese Junipers, Juniperus chinensis L., associated with Pestalotia funerea Desm.During the summer of 1957 most of 200 Chinese junipers in
a Victoria nursery, consisting of prostrate forms 2 feet or more
wide and erect forms 2 to 3 feet tall, were severely damaged.
Lesions, many of them girdling, were observed on twigs, on
main stems at ground level, and on main branches of prostrate
forms where they touched the ground. Examination by
Mr. G. S. Brown, Plant Protection Division, Victoria, failed
to reveal any evidence of entomological association.
Attempts were made to isolate and identify fungi from
the lesions. Twelve sections, 10 to 20 mm. in diameter by
approximately 150 mm. long, were taken from diseased
tops of different plants and incubated in a humid atmosphere
under bell-jars. After a week of incubation, spore tendrils
extruded from places on all sections. The spores coming
from 11 sections were characteristic of Pestalotia, funerea
Desm., although tendrils of Macrophoma-like spores were
also found on one of the eleven. The spores extruding from
the twelfth section belonged to Monochaetia sp.
From two root systems similarly incubated, only Mucoraceae developed. Cultures obtained from excised bits of
dead inner bark taken from above—and below—ground parts
of ten jumpers were of several kinds, including Pestalotia
funerea from three of the ten trees. Rots that developed
in ten apples inoculated with soil taken from near the juniper
roots were associated with Pythium sp. in eight apples and
Pestalotia sp. in two apples.
It is believed that P. funerea caused the
observed. At the affected nursery, P. funerea is associated
with commonly occurring tip-blight of junipers and other
Cupressineae, so that inoculum is frequently abundant. The
attack reported here is noteworthy because the fungus, a
weak pathogen that is rarely evident on stems or branches
7 mm. or more thick at point of infection, was associated
with large lesions on main branches or stems of Chinese
juniper. Predisposition to' infection by weakness or injury
is suspected. In 1956 severe damage, consisting of girdling
EDMOND CLOUTrER, C.M.G., O.A., D.S.P.,
at ground-level, had been noted on less than 20 erect junipers.
Although P. funerea was among the fungi that had been
isolated from those trees, the damage had been attributed,
in part, to the November 11th, 1955, frost.—P. J. Salisbury.
RECENT PUBLICATIONS
Bergold, G. H. and Ripper, W. E. The polyhedral virus of
Heliothis armigera (Hbn.). Nature 180: 764-765. 1957.
Chapman, J. A. A further consideration of summit ant
swarms. Can. Ent. 89: 389-395. 1957.
Clark, R. C. and Brown, N. R. Studies of predators of the
balsam woolly aphid, Adelges piceae (Ratz.). III. Field
identification and some notes on the biology of Neoleucopie pinicola Mall. Can. Ent. 89: 404-409. 1957.
Cockerill, J. Experiments in the control of damping-off at
the nursery, Orono, Ontario. For. Chron. 33: 201-204.
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Davidson, A. G. Studies in forest pathology. XVI. Decay
of balsam fir, Abies balsamea (L.) Mill., in the Atlantic
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Etheridge, D. E. A method for the study of decay resistance in wood under controlled moisture conditions.
Can. J. Bot. 35: 615-618. 1957.
Etheridge, D. E. Moisture and temperature relations of
heartwood fungi in subalpine spruce. Can. J. Bot. 35:
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Mott, D. G., Nairn, L. D. and Cook, J. A. Radial growth
in forest trees and effects of insect defoliation. Forest
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Parker, A. K. The nature of the association of Europhium
trinacriforme with pole blight lesions. Can. J. Bot. 35:
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Redmond, D. R. Observations on rootlet development in
yellow birch. For. Chron. 33: 208-212. 1957.
Sager, S. M. A virus disease of western hemlock looper,
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3: 799-802. 1957.
Thomas, J. B. The use of larval anatomy in the study of
bark beetles. Can. Ent. Suppl. 5. 1957.
Ziller, W. G. Studies of western tree rusts. III. Milesia
laeviuscula, a needle rust of grand fir. Can. J. Bot. 35:
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Queen's Printer and Controller of Stationery, Ottawa, 1957.
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