AP003 Management of Apple Dimpling Bug Dr Colin Bower

Transcription

AP003
Management of Apple Dimpling Bug
Dr Colin Bower, et at
NSW Agriculture
AP003
This report is published by fte Horticultural Researdi and
Development Corporation to pass on informadcm concerning
horticultural researdi and devdopment undertaken for the
s^ple and pear industry.
The research contained in tiiis report was fonded by the
Horticultural Researdi and Devdopment Corporation vnSi
the finandal support of the apple and pear industry.
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©Copyright 2000
HROVC
HORTICULTURAL
RESEARCH &
DEVELOPMENT
CORPORATION
Partnership in
horticulture
HORTICULTURAL RESEARCH AND DEVELOPMENT CORPORATION
FINAL REPORT
Project AP003
(1 July 1990 to 30 September 1993)
Management of Apple Dimpling Bug
Dr Colin Bower et al
NSW Agriculture
Final Report on HRDC Project AP003
Management of Apple dimpling bug
Principal Investigator:
Dr Colin Bower
Program Leader (Extensive Horticulture)
NSW Agriculture
Locked Bag 21, Orange NSW 2800
Collaborators:
Mr FD Page, DPI Queensland
Queensland Horticultural Institute, Applethorpe, Queensland
Mr DG Williams, Agriculture Victoria
Institute for Horticultural Development, Knoxfield, Victoria
Mr W Woods, Agriculture Western Australia
Midland District Office, Midland, Western Australia
Purpose of this Report:
The biology of apple dimpling bug is poorly understood in comparison with other major apple
pests.
This report records the results of three years of research into apple dimpling bug in four states
(NSW, Qld, Vic and WA). The origin of infestations, the major alternative plant host, the
susceptibility of various apple cultivars, alternate chemical control measures, the most
susceptible periods during flowering and internal damage caused by apple dimpling bug are
documented.
Funding Sources and Collaborative Institutions:
AAPGA, HRDC, NSW Agriculture, Agriculture Victoria, Agriculture Western Australia, DPI
Queensland
Disclaimers:
The information contained in this publication prepared by NSW Agriculture is based on
knowledge and understanding at the time of writing (April 2000). However, if because of
advances in knowledge, users are reminded of the need to ensure that information upon which
they rely is up to date and to check currency of information with the authors.
Any recommendations contained in this publication do not necessarily represent current HRDC
policy. No person should act on the basis of the contents of this publication, whether as to
matters of fact or opinion or other content, without first obtaining specific, independent
professional advice in respect of the matters set out in this publication.
The symbol
used in this report indicates a registered trade name
CONTENTS
INDUSTRY SUMMARY
Page 2
TECHNICAL SUMMARY
Page 3
1.
Introduction
Page 4
2.
Objectives of project
Page 5
3.
Technical Report 1
Identification of the host plants of apple dimpling bug
Page 6
4.
Technical Report 2
Susceptibility of apple varieties to attack from apple dimpling bug
Page 10
5.
Technical Report 3
Pre-bloom pesticide applications for control of apple dimpling bug
Page 16
6.
Technical Report 4
Page 23
Evaluation of trapping and blossom jarring for monitoring apple dimpling bug
7.
Technical Report 5
Page 51
Susceptibility of stages of apple development to injury from apple dimpling
bug from bud separation to fiiiit set
8.
Technical Report 6
Identification of damage to fruit by apple dimpling bug
Page 80
9.
Conclusion
Page 88
10.
Technology transfer summary
Page 89
11.
Recommendations to industry
Page 90
12.
Acknowledgments
Page 91
13.
Literature
Page 92
Page 1
INDUSTRY SUMMARY
Apple dimpling bug (ADB) (Campylomma liebknechti (Girault)) (HEMIPTERA:
MIRIDAE) is one of the most serious pests of apples. Bugs suddenly invade orchards in
spring during blossoming and feed on the ovaries of the flowers. The piercing, sucking
damage results in malformations or dimpling as the apples grow.
A survey of 102 apple orchards at Orange in 1987 reported an average loss due to apple
dimpling bug (ADB) of 8.8%, downgrading reducing profit by 20.2%.
Two of the main varieties of apples grown in Australia, Delicious and Granny Smith are
highly susceptible to ADB attack. Monitoring the crop becomes very difficult as the
recommended chemical, endosulfan, has a short residual life. More efficient spraying
strategies will reduce losses in yield and the use of pesticides in situations where they are
being applied imnecessarily.
In this project we have:
• defined ADB damage by comparing damage in sprayed and unsprayed finit
• shown that patterns of internal damage confirm external ADB damage symptoms
• evaluated monitoring methods for ADB populations
• examined the alternate hosts of ADB
• assessed the susceptibility of different apple cultivars to ADB injury
• defined the susceptible stage of apple blossom to ADB attack
• compared chemical control strategies.
ADB survive and breed on many plant species. Growers should be aware that wattles and
other flowering plants can be a source of ADB to invade orchards and that the severity of an
invasion varies from year to year.
Fruit needs to be protected from pink blossom stage to one week post petal fall.
Chlorpyrifos and fluvalinate gave the best results of chemicals tested. Chlorpyrifos is toxic to
bees and must be applied pre-bloom. Fluvalinate is toxic to predatory mites and interferes
with integrated mite control. Chlorpyrifos is the best choice for prophylactic application at
pink. Carefiil monitoring of pest populations is required so that growers can decide if
additional endosulfan sprays are required.
Limb jarring is the most effective method of monitoring ADB numbers, although white sticky
traps can be usefiil.
All apple varieties investigated were equally attractive to ADB, some cultivars show less
effects of ADB damage than others. Jonathan, Pink Lady and Lady William were more
resistant to ADB injury.
Severely damaged fruit is shed preferentially and leads to crop reduction.
ADB feed mainly on the vascular tissue of the ovary of the flower.
Further studies on ADB populations in pastoral areas and the relationship with weather
systems would be usefiil to the industry, so that invasions can be predicted.
The resistance of Jonathan varieties requires fiirther study. The inability of the ADB feeding
stylus to penefrate the hairy ovary of Jonathan cultivars may lead to a breeding program
selecting for this characteristic.
Further biological studies may show why the severity of ADB invasions varies from year to
year.
The development of an ADB pheromone may be useful in monitoring ADB populations.
Page 2
TECHNICAL SUMMARY
The apple dimpling bug (ADB) Campylomma liebknechti is one of the most serious pests of
apples in mainland Australia. Bugs suddenly invade orchards during blossoming and feed on
the ovaries of flowers and developing fruitlets after flowering. The resultant injury causes
dimple-like malformations as the fruit grows. Any failure to detect and adequately control this
pest during flowering can result in serious losses due to dovmgrading of fixiit at harvest.
The following investigations were undertaken:
• Methods of monitoring ADB populations were compared in order to obtain information on
the origin of infestations in orchards.
• Alternate hosts of ADB were investigated.
• Determination of the factors affecting the severity of damage caused by ADB. This
involved caging experiments in NSW. Varietal susceptibility trials were carried out in
NSW and WA.
• Trials to evaluate the effects of strategic spraying of alternate chemicals were conducted in
Victoria and Queensland.
ADB survive and breed on many plant species, ADB were found on 62 species from 18 plant
families in NSW, Qld, WA and Vic. Wattle {Acacia spp.) are important hosts across Australia.
ADB move from one flowering host to another, in arid aireas dispersing over long distances.
Some varieties show less effects of ADB attack than others.
All apple varieties investigated were equally attractive to ADB. However Jonathan cultivars
being most resistant to ADB attack.
Chlorpyrifos and fluvalinate gave the best control of the chemicals tested.
Blossom jarring is the most reliable method of monitoring for ADB.
The critical period when blossom is susceptible is from pink to one week post petal fall.
Severely damaged fruit are shed preferentially, reducing yield.
ADB feed mainly on the vascular tissue of the ovary.
As a result of this project the following can be concluded:
• the severity of ADB invasion varies from year to year
• other host plants can be a source of bugs that can invade orchards
• fioiit need to be protected from pink to one week post petal fall
• the difference in susceptibility of different cultivars is worthy of investigation
• chlorpyrifos is the best choice for prophylactic application at pink, but careful monitoring
of pest populations is required so that growers can decide if additional 'bloom' sprays are
required
Further studies on ADB populations in pastoral areas and the relationship with weather
systems would be useful to the industry, so that invasions can be predicted.
The resistance of Jonathan varieties requires fiirther study. The inability of the ADB feeding
stylus to penetrate the hairy ovary of Jonathan cultivars may lead to a breeding program,
perhaps selecting for this characteristic.
Further biological studies may show why the severity of ADB invasions varies from year to
year.
The development of an ADB pheromone may be useful in monitoring ADB populations.
Page 3
INTRODUCTION
Apple dimpling bug {Campylomma liebknechti (Girault)) (HEMIPTERA: MIRIDAE) is
one of the most serious pests of apples. It is a little known native insect that feeds by piercing
the skin of plants and probing deeply for juices with its sharp sucking mouthparts.
Bugs invade apple orchards in spring during blossoming and feed on the ovaries of the
flowers. The resultant injury causes dimple-like malformations as the fruit grows. An area of
russetting is often associated with the dimple. The size of dimples varies considerably, the
smallest ones are unimportant, but larger ones cause downgrading of fruit and economic loss.
ADB can cause relatively high levels of damage to Delicious and Granny Smith varieties in
some years. The economic importance of apple dimpling bug (ADB) has been gradually
increasing with ever more stringent demands for perfect fruit in the market place. This is
shown by the fact that ADB was not recognised as a pest until 1950, and by increasing calls
from growers for research into ADB control.
The severity of ADB infestations varies greatly between the years with consequent variation
in the need for control measures. At present the factors responsible for this variation are
unknown and it is not possible to predict the occurrence of severe outbreaks. ADB is an insect
which has not yet been studied in any detail and is poorly xmderstood in comparison with the
other major pests of apples.
Little is known of how ADB survive and proliferate in the natural environment.
In the past DDT provided fruitgrowers with excellent control of ADB and was relatively safe
to bees which are essential for pollination of flowers. The harming of DDT has greatly
increased the significance of ADB. Ensosulfan replaced DDT but while safe to bees, it was
much less effective against ADB than DDT, and growers in many areas cannot obtain
adequate control with it. Fluvalinate (Klartan ®),registered in 1989 provides control
equivalent to DDT and is safe to bees, but is highly toxic to predatory mites and disrupts
integrated mite control. Growers practising integrated mite control have a difficult choice to
make between endosulfan and fluvalinate. Chlorpyrifos has been shown to be effective against
ADB but is toxic to bees unless applied 2-3 days before bees are foraging.
Apple dimpling bug is a difficult pest to monitor, so a range of monitoring methods was
investigated, particulary the use of white sticky traps which have been used in the United
States of America (Coli, Green et. al., 1985).
Very little is known about the biology of ADB. Chinajariyawong and Walter (1990) studied
the feeding biology of ADB on cotton plant organs, with and without Heliothis spp. eggs as a
food supplement. They showed that the bug was predatory as well as plant feeding. They also
showed that it had a short life cycle and a wide range of hosts.
Page 4
OBJECTIVES OF PROJECT
The findings of this project are reported as six separate trials, conducted by collaborators in
four states. Each of these trials are treated as six separate mini reports. The following outlines
the objective of each trial:
Report 1.
To identify the sources of apple dimpling bug infestations in apple orchards.
Report 2.
To determine the susceptibility of different apple varieties to apple dimpling
bug attack.
Report 3.
To compare the efficacy of various pesticides against apple dimpling bug.
Report 4.
To compare various methods of monitoring apple dimpling bug.
Report 5.
To identify the critical stage of flower or fiiiit development susceptible to
apple dimpling bug attack.
Report 6.
To document types of damage to apple caused by apple dimpling bug.
Pages
TECHNICAL REPORT 1
IDENTIFICATION OF THE HOST PLANTS OF APPLE DIMPLING BUG
{Campylomma liebknechti (Girault)) (Hemiptera: Miridae).
W. WOODS
Agriculture Western Australia, Midland WA 6056
Aim
To find the source or sources of ADB infestations in apple orchards.
Introduction
In winter when apples are dormant they are not hosts for ADB. As a native species it has been
assumed that native plants are the most important hosts although ADB has been found on
various ornamental and crop plants Bodnaruk (1992), Chinajariwong and Walter (1990),
Lloyd, N.C. (1969), Malipatil (1992), Thwaite (1992).
Published data suggest ADB survives and breeds in many plant species. However it is of
considerable interest to determine whether any particular species are major or dominant hosts
for ADB in areas where apples are grown. In particular it is important to know if there are
particular alternate hosts which may provide major sources of ADB for invasion of orchards
when flowering begins. With this knowledge it may be possible to manage alternate hosts
within and near orchards to reduce ADB incidence on apple trees.
Materials and methods
Both native and introduced vegetation were sampled for ADB in 1991, 1992 and 1993 in
Queensland, NSW, Victoria and Western Australia. Plants were identified to species wherever
possible. The site of sampling was recorded as the nearest town.
In the 1991-1992 season at Orange weekly sampling was carried out on Wattle {Acacia sp.),
Chinese Hawthorne {Photinia sp) and Tree Lucerne (Chamaecytisus prolifer) (23 September,
1991 to 2 December 1991). Ten taps from each of 5 trees of each species were made weekly
between these dates.
Results
Hosts of ADB, listed alphabetically by plant family are listed in Table 1. Resuhs of sampling
at Orange are seen in Table 2. Maximum counts of ADB on an individual tree was 5.9/tap
ixova. Acacia at Orange in September 1991.
Page 6
Table 1.
Hosts of apple dimpling bug
Family
Asteraceae
Boraginaceae
Brassicaceae
Caesalpinaceae
Fagaceae
Fabaceae
Geraniaceae
Myrtaceae
Meleaceae
Mimosaceae
Oleaceae
Proteaceae
Species
Achillea millifolium
Echium plantagineum
Rhaphanus raphanistrum
Sisymbrium irio
Sisymbrium orientale
Cassia nemophila
Ulex europaeus
Castanea populneus
Viciafaba
Lupinus angustifolium
Robinia pseudoacacia
Erodium crinitum
Callistemon sp.
Kunzea oppositifolia
Melaleuca sp.
Thryptomene sp.
Leptospermum sp.
Chamelaucum uncinatum
Scholtzia
Leptospermum polygalifolium
Melia azedarach
Acacia sp.
Acacia baileyana
Acacia coronata
Acacia crassicarpa
Acacia decora
Acacia dealbata
Acacia fimbriata
Acacia implexa
Acacia longfolia
Acacia mearnsi
Acacia melanoxylon
Acacia neriifolia
Acacia obtusifolia
Acacia polyalrifolia
A cacia polybotrya
Acacia pycnantha
Chamaecytisus proliferus
Ligustrum vulgare
Forsythia sp.
Grevillea sp.
Hakea sp.
Macadamia integrifolia
Page?
State
Queensland
Western Australia
Queensland
Queensland
Queensland
Western Australia
New South Wales
Queensland
Queensland
Western Australia
New South Wales
Queensland
New South Wales
Queensland
Queensland, Victoria, Western
Australia
Western Australia
Western Australia
Western Australia
Western Australia
Western Australia
Queensland
New South Wales
Queensland
Queensland
Queensland
Queensland
Queensland
Queensland
Queensland
Queensland
Queensland, New South Wales
New South Wales
Queensland
Queensland
Queensland
Queensland
Victoria
Victoria, Queensland, New South
Wales
Queensland
New South Wales
Western Australia
Western Australia
Queensland
Photinia glagra
Photinia robusta
Prunus amygdalus
Prunus armeniaca
Prunus aviam
Pryus calleryana
Pyrus communis
Pryus pryiofolia
Spiraeae prunifolia
Salix sp.
Brachychiton populneus
Pimelia sp.
Virus vinifera
Salicaceae
Steruliaceae
Thymelaceae
Vitaceae
Table 2.
Queensland
New South Wales
Victoria, New South Wales
Queensland, Victoria, Western
Australia, New South Wales
Queensland
Victoria, New South Wales
Queensland
New South Wales
New South Wales
Queensalnd
New South Wales
Victoria
Queensland
New South Wales
Queensland
Western Australia
Victoria
Plantago lanceolata
Cotoneasta pannosus
Crataegus monogyna
Mains domesticus
Plantaginaceae
Rosaceae
Number of ADB/tap' at Orange, New South Wales on Wattle, Chinese
hawthorn and Tagasaste.
Date
Wattle
{Acacia sp.)
Chinese hawthorn
{Photinia robusta)
23.09.91
03.10.91
08.10.91
14.10.91
21.10.91
28.10.91
04.11.91
11.11.91
18.11.91
25.11.91
02.12.91
1.5
0.8
0.3
0.1
0.1
0.1
0.4
0.3
0.3
0
0.4
0.2
0.3
0.3
0.7
0.7
0.1
0.7
0.4
0
0
0.2
Average of 10 taps from 5 trees of each species
Pages
Tagasaste
{Chamaecytisus
proliferus)
1.4
0.9
0.3
0.2
0.2
0.1
0
0
0
0
0
Discussion
ADB were found on 62 species fi-om 18 plant families. This compares to the 37 species from
16 families documented by Malipatil (1992). In total ADB is known to attack plants from 26
families making it truly polyphagous.
ADB were found on both introduced and native species, on annual perennials, on plants with
yellow, white and purple flowers and in all months except March and April.
It appears that ADB can breed throughout the year on whatever species are in flower at the
particular time. Abundance will increase in spring when temperature and moisture are
favourable. Flowering and increasing temperature will increase ADB fecundity. Wattle is an
important host across Australia and large numbers could breed up on a single tree.
As ADB obviously utilise a number of hosts it has probably developed a dispersal mechanism
that enables it to find new hosts when its current host becomes unattractive. In arid Australia
where rainfall can be scarce and patchy this involves dispersal over long distances. This
could explain the invasion of ADB into fruit growing areas in spring although it is apparent
that a residual population will always be present on local native, ornamental and crop plants.
In orchard areas such as Orange in NSW, where little natural vegetation exists in the
orcharding areas, wattles and other plants such as Tagasaste growing along roadsides are
obvious sources of immediate ADB populations which can invade orchards when flowering
ceases. Indeed with some wattles flowering ceases at around the same time apples are
beginning to flower. Therefore, by spraying these bushes at flowering orchardists may
reduce the risk of attack to adjacent orchards.
With respect to long distance migration, at present we can not accurately predict what
populations in pastoral areas will cause damaging populations in orcharding areas. This is not
only a fiinction of high numbers being available because of a good season but also of weather
conditions suitable to move them to orcharding areas. Further study of populations is pastoral
areas on weather systems is required, similar to that carried out with remote area breeding and
movement of the cotton boUworm.
Page 9
TECHNICAL REPORT 2
SUSCEPTIBILITY OF APPLE VARIETIES TO ATTACK FROM APPLE
DIMPLING BUG (Campylomma liebknechti (GIRAULT)) (HEMIPTERA: MIRIDAE).
W. WOODS
Agriculture Western Australia, Midland WA. 6056.
Aim
To investigate the susceptibility of different apple varieties to apple dimpling bug
Campylomma liebknechti (Girault))(Hemiptera:Miridae) (ADB) attack and determine the
reason for this varying susceptibility.
Introduction
It is commonly known that apple varieties vary in their susceptibility to damage caused by
ADB attack. The reason for this difference in susceptibility has never been clearly understood,
and may be because ADB are not attracted to Jonathan flowers or because the apple itself is
resistant to ADB attack.
In W.A. the new varieties Sundowner and Pink Lady are widely planted. Early research
results and anecdotal evidence suggested that Pink Lady, like Jonathan was only slightly
affected by ADB damage (Sivyer 1990). The resistance status of other new varieties was also
unclear. If shown to be resistant to ADB attack this would be another factor in favour of
planting these new varieties.
Susceptibility to ADB attack was investigated in NSW and WA.
a.
BathurstNSW
The trial site in NSW was a block of 189 Delicious, Jonathan and Granny Smith trees in the
Bathurst Horticultural Research Station (Figure 1). Nine trees of each variety were sampled.
ADB numbers on each of these were monitored by tapping 50 blossom clusters per tree into a
plastic icecream container, 7 times in 1990 and 1991, and 6 times in 1992. At harvest in each
of the three seasons the ADB damage on each tree was assessed. In total 12444, 8410 and
11809 fruit were inspected in 1991,1992, and 1993 respectively.
Page 10
xxxxxxxxxxxxxxxxxxxxx
++ + + + + + + + + + + + + + + + + + + + + +
X
Delicious
++ + + + + + + + + + + + + + + + + + + + + +
+
Jonathan
+++++++++++++++++++++++
o
Granny Smith
ooooooooooooooooooooo
Figure 1.
b.
Layout of varietal susceptibility trial, block 3 of I Block,
Bathurst Agricultural Research Station 1990
Stoneville WA
In WA two different apple blocks on Stoneville Horticultural Research Station were used. In
1991 the trial site was mixed block of 174 apple trees including the four varieties: Lady
Williams, Pink Lady, Sundowner and Gala. Five trees of each variety were sampled 8 times
from October 18 to November 6 for ADB by tapping fifty blossom clusters from each tree
into a plastic icecream container and counting the number of ADB.
On 12 December 1991 and 25 January 1992, 25 fruit from each of these trees were visually
inspected on the tree for ADB damage. At harvest the total fruit on each tree (0-890) was
assessed for ADB damage.
The trial site in 1992/93 was a close planted apple variety assessment block. There were 12
rows of trees, each row with 30 trees. Varieties were planted in blocks of five adjacent trees
and there were six varieties in each row. There were six replicates of each variety tested: Pink
Lady, Gala, Svmdowner, Fuji, Red Fuji and 53/16. As in 1991, 50 blossom clusters were
tapped into an icecream container and the numbers of ADB counted. From October 16 to
November 16 1992 tapping was carried out on 13 separate occasions and numbers totalled for
each variety. Damage was assessed by inspecting 50 fruit per replicate on December 2 and
between 411 and 1222 fruit per variety at harvest. At harvest an overall classification of
market quality was assigned to each damaged fruit. The damage was classified as:
1. Clean
2. Class 1
-
no damage due to ADB
total damage to the fruit surface due to ADB fit
within a 5 mm diameter circle.
Page 11
pronounced dimple or multiple dimples covering
an area greater than a 5 mm diameter circle.
severely dimpled fruit, unsaleable.
3. Class 2
4. Juice
Results
Bathurst, NSW
a.
At Bathurst Jonathan apples show significantly less damage in all years. Delicious apples had
less damage than Granny Smiths in all years except 1990 when there was no difference.
There was no difference in number of dimple bugs found on all varieties (Table 1) (Figure 2).
Table 1.
Delicious
Delicious
Jonathan
Granny
Percent fruit damage and Mean ADB number per tree/ per variety at
Bathurst in 1991,1992 and 1993.
1991/92
% fruit
Mean
damage
No. ADB
(n=9)
12.3"
85.7
0.4"
109.2
25.8'
68.3
1990/91
% fruit
Mean
damage
No. ADB
(n=9)
11.7"'
15.6
l.l''
14.2
11.4"
16.6
1992/93
% fruit
damage
14.9"
1.7"
22.2'
Mean
No. ADB
(n=9)
69.6"
98.7"
110.9"
Within a column figures followed by the same letter are not
significantly different
(Analysis of variance).
Figure 2.
Varietal differences and ADB numbers , Bathurst 1990-93
1990/91
1991/92
120
120
100
100
80
80
60
60
40
40
•
20
0
20
^•ri
Delicious
^
Jonathan
d
Oeli<aous
•'Granny Smith
1992/93
120
• % damage D N o A D B
100
80
^
60
40
20
0
Delicjous
Jonathan
Page 12
11
G 'ann)'Smith
Jonathan
•
Gfanny Smith
At Stoneville in 1991/1992 season numbers of ADB collected per tree over the flowering
period on different varieties ranged from 18.4 to 28.5.
Only a small amount of fruit was harvested from most varieties because of low chill hours and
there was no significant difference in damage at harvest between varieties. Some natural
thinning of fruit appears to have occurred, as evidenced by the difference in damage between
earlier and later assessments. (Table 2)
Table 2.
Percent damage to apples 1991/1992 Stoneville Research Station.
Variety
% damage at
11 Dec
P. Lady
Gala
Sundowner
L Williams
16.0
6.4
5.6
13.6
% damage at % damage at Mean
tapped
harvest
15 Jan
tree
19.3
18.0
4.3
15.7
4.8
5.3
4.8
21.3
1.8
23.8
12.0
2.5
ADB
per
In 1992/1993 ADB damage at harvest was highest for Red Fuji and Gala and lowest for Pink
Lady and 53/16 (Table 3). Damage decreased during the season once again suggesting
natural thinning or that apples grow out of slight ADB damage. Again there was no obvious
relationship between numbers of ADB tapped and damage at harvest. Although Pink Lady
had one of the lowest percentage of fruit damaged it also had by far the highest percentage of
fruit in the most severe damage category (Figure 3).
Table 3.
Percent damage to apples 1992/93 season - Stoneville Research Station
Variety
% damage at
2/12/92
% damage at
harvest
Pink Lady
Gala
Sundowner
Red Fuji
Fuji
53/16
72
76
86
81
73
62
10.4^'
47.8"
34.8^
48.4"
16.3"
9.0"
Mean number of
ADB tapped
for season (n=6)
314
312
385
328
312
325
Within a column figures followed by the same letter are not significantly difference
(Analysis of variance).
Page 13
60
•
50
ADBNO.1
n A D B N o . 2 H ADB No.3
u 40
1
« 30
Q
20
;I:I:I::::::::-I:l:i
10 -
jiiijiilij|iiijiii
.
0
Fuji
Figure 3.
Red Fuji
Gala
Pink Lady 53/16 Sundowner
Varietal differences and ADB damage classification, Stoneville 1991/92
Discussion
Although there were obvious differences in the numbers of ADB between states and in
different years, in a particular year and at a particular site all varieties seem equally attractive
to ADB. At Bathurst more apple dimpling bug were found on Jonathan than on Delicious in
two of the years yet damage to Jonathan remained at a very low level. It remained at this low
level no matter how ADB numbers fluctuated. With Delicious the degree of damage did not
increase as ADB numbers rose, whilst the damage to Granny Smith did increase as ADB
number rose(Figure 2)
It seems that Jonathan apples have an inherent resistance to ADB attack that is not related to
any lower degree of attractiveness to ADB adults. It has been suggested that the resistance
mechanism may be the hairy ovary which prevents penetration of the ADB feeding stylus
(Bower: pers. Comm). This needs to be investigated fiirther as it may be possible to select
apples in a breeding program that show Jonathan type resistance to ADB attack.
During the 1991 grovmig season in the Perth Hills above average temperatures prevailed and
as a consequence chilling hours were below requirements for consistent flowering and fruit
set. Flowering was erratic within and between trees of the same variety and some trees did
not set any fruit. There was no significant difference in damage between any of the varieties
at harvest with the low variable yield of fruit contributing to this result. The consistency of
the on-tree damage assessments in December and January suggests that it was after this date
either preferential thinning occurred or the fruit grew out of minor dimpling.
Page 14
In WA in 1992 large numbers of ADB were present throughout the flowering season. They
caused severe damage to some varieties. All varieties had commercially unacceptable levels
of damage which was to be expected considering the intensity of ADB attack. The varieties
Pink Lady and 53/16 both have Lady Williams as the same parent and there may be a genetic
basis to their lowered susceptibility to attack. Unfortunately Sundowner also has this shared
heritage and it was severely damaged. Sundowner flowers early and is exposed to ADB
attack before the other varieties which may partially explain its increased damage. Damage to
all varieties assessed in December was remarkably uniform with high percentages of fiaiit
dimpled. However, by harvest this had dropped, especially with Pink Lady and 53/16
suggested self thirming with these varieties. The small percentage of Pink Lady finit in the
lowest damage category indicates that Pink Lady fi-uit does indeed grow out of minor damage
and only minor and severely damaged fiaiit remain at harvest.
Page 15
TECHNICAL REPORT 3
PRE-BLOOM PESTICIDE APPLICATIONS FOR CONTROL OF APPLE DIMPLING
BUG {Campylomma liebknechti (GIRAULT)) (HEMIPTERA: MIRIDAE).
D.WILLIAMS\ F.PAGE' AND P.NIMMO'
1. Agriculture Victoria, Institute for Horticultural Development, Private bag 15, South Eastern
Mail Centre, VIC 3176
2. Queensland Dept. Primary Industries, Granite Belt Horticultural Research Station, PC Box
501, Stanthorpe,
QLD 4380
Aim
This paper reports the results of pesticide trials conducted as part of a large collaborative
research project on ecology and management of ADB.
Introduction
This project aims to obtain information from which strategies for optimum use of endosulfan,
chlorpyrifos and fluvalinate can be formulated. In particular, critical times for spraying are to
be defined to enable most effective use to be made of endosulfan.
1991-92
Victoria:
A spray trial to assess the efficacy of a range of chemicals against ADB was established in an
orchard at Harcourt, Central Victoria in October 1991. Trial sites were difficult to obtain
because growers were reluctant to risk large areas of crop. The trial site was the outer 2 rows of a
close planted block of red delicious apples bordering native scrub, and having a history of ADB
attack. Trial design was a randomised single tree replicated plot with 5 replicates of 5 treatments.
Each treated tree was separated from the next by 2 "unfreated" bviffer trees. All treatments were
applied once at the late pink-bud stage of tree development. The trees were sprayed to run-off
using a hand gun attached to a Hardi frailer mounted power sprayer operating at 1400 kpa.
Weather conditions were overcast with occasional suimy periods, maximum temperature 20°C,
wmd SSW 4-10 kph. Treatments appUed were fenthion (Lebaycid^ @ 70mL product/lOOL),
fluvalinate (Klartan*^ @ 20mL product/1 OOL), azmphos-methyl (Gusathion^ @ 140g
product/1 OOL), trichlorphon (Dipterex*^ @ 75g product/1 OOL) and chlorpyrifos (Lorsban^ @
200g product/1 OOL).
Page 16
Treatments were applied in the order azinphos-methyl, chlorpyrifos, fenthion, trichlorfon,
fluvalinate with the spray tank and lines being flushed and thoroughly cleaned between
treatments.
Bee toxicity was not evaluated because bees were not available until 7 days post treatment, the
plots were too small, and the rest of the orchard was treated with chlorpyrifos by the grower.
Bug numbers were assessed by blossom jarring (50 inflorescences/tree) three times/week until
petal fall. Bug days were calculated using the method of Bower et al (1993) and used to
measure the cumulative bug activity during bloom.
Damage was assessed at harvest by removing all fruit from the trees and scoring them as either
clean or damaged by ADB. Data were analysed by generalised linear model (GLM) using
Genstat 5 release 1.3. Data from frees with less than 120 fruit were excluded from the analysis.
1992-93
Victoria:
The 1991-92 frial site was abandoned in favour of a larger site which also allowed a blocked
design. The two best performing freatments from 1991-92 were compared to an unfreated
confrol. The new site was a mixed block of red and golden delicious apples at Arthur's Creek,
north of Melbourne. The block was set out in 3 bays with each bay containing a series of 2 rows
of red delicious (RD) separated by 4 rows of golden delicious (GD), which allowed a 3x3 latin
square design to be used. The RD were used as treatment frees and the GD served as guard rows.
All treatments were applied by the orchardist using an airblast sprayer delivering 2000L/ha. Two
sticky fraps were placed in each plot on 12 October 1992 and a free adjacent to each sticky frap
was used for blossom jarring. Sampling took place 17 October, 20 October, 27 October and 3
November. Six beehives were placed in the GD rows between freatments at 8.00am on the day
following spraying. Dead-bee fraps were attached to each hive. Dead bees were collected from
each hive, counted, and each day's collection was pooled for residue analysis. The State
Chemistry Laboratory conducted analysis of chlorpyrifos residues in the dead bees, with a limit
of detection of O.Olmg/kg. A preliminary inspection of ADB damage was made on 2 December
by sampling 100 fruit from each of 3 sample frees in each plot. A final assessment was made at
harvest by sampling all fiuit from each of 5 trees in each plot. Data were analysed by GLM
using Genstat 5.
Queensland: Two additional trials were established in Queensland at the Granite Belt
Horticultural Research Station. Both trials used a randomised block design with 5 replicates. The
first ttial (Baronios) used Graimy Smith apple frees spaced at 6m x 6m, with 2-free plots and 5
treatments (trichlorfon 0.05%, fenthion 0.05%, azinphos-methyl 0.05%, chlorpyrifos 0.05%, and
fluvaluiate 0.005%). The second trial (Special Area) used suigle free plots of Delicious apple
trees spaced at 6m x 3m with a guard free between freatments. This trial used the same
freatments as thefiirst,with the addition of an unsprayed check. All freatments were applied to
runoff, using a portable spray unit with hand lance, at the early pink bud stage. Bug populations
were monitored in the same way as the Victorian trials: sticky fraps and blossom jarring. Fruit
damage was assessed in early December by taking a random sample of 40 fruitlets/free. A fmal
assessment was conducted at harvest, with fruit being scored as clean, class 1, class 2 or juice
according to NSW fiuit grade standards. The Baronios site had very heavy fruit set and a
random sample of 500 apples/free was harvested. In the Special Area all apples were harvested
and approximately 350 per treatment plot were assessed.
Page 17
Results
1.1991-92
Victoria:
No bee deaths were noticed and the beekeeper was happy with the condition of his hives when
they were removed at the end of flowering. The flowering period was short with only 15 days
between late pink bud and complete petal fall. ADB was recorded on only 10 of the 25 trial
trees. Damage by ADB is cumulative during flowering so the severity of the infestation was
determined by calculating the total number of bug days for each treatment. Fruit damage and
bugdays are presented m Table 1 below.
Table 1.
Fruit damage at harvest 1992 and total bugdays experienced over the flowering
period at Harcourt.
Treatment
% ADB damage''
Total bugdays
fenthion
3.55 a
5.5
fluvalinate
2.15 b
0.0
azinphos-methyl
6.84 c
18.0
trichlorfon
3.50 a
13.5
chlorpyrifos
2.44 ab
2.5
* numbers followed by the same letter are not significantly different (p>0.05_)
' excluding trees with less than 120 fiîit/tree
2. 1992-93
Victoria:
Chlorpyrifos residues of 0.07mg/kg were detected in dead bees collected on the second day after
spraying. No residues were detected in any subsequent samples of dead bees (Table 2). The
flowering period was short (17 days) but sUghtly longer than 1991-92, and weather conditions
were so wet that blossom jarring was only feasible ftom full bloom onwards. No ADB were
detected by blossom jarring in any of the treatments but small numbers were caught in the sticky
traps (Table 3). The early December damage assessment only detected 4 ADB damaged fruit in
a total sample of 2700 fruit. A much larger sample was taken at harvest and the results are
presented in Table 4.
Page 18
Table 2.
Dead honeybee coimts and chlorpyrifos residues.
Days after application
of chlorpyrifos
pooled
residue
(mg/kg)
Hive number
1
2
3
4
5
6
2
75
51
90
35
43
80
0.07
3
26
27
46
13
25
41
-
4
89
44
135
38
62
138
-
6
72
115
180
50
61
150
-
Tables.
Treatment
unsprayed
chlorpyrifos
fluvalinate
ADB numbers caught ui sticky traps, Arthur's Creek, Victoria 1992
rep
Total
Bugdays
Bug nximbers*
12
Oct
17
Oct
20
Oct
27
Oct
3
Nov
1
0
1
2
0
1
2
0
3
3
0
0
3
0
5
6
0
0
total
0
9
11
0
1
1
0
3
3
0
0
2
0
5
5
0
0
3
0
0
0
0
0
total
0
7
8
0
0
1
0
2
2
0
0
2
0
3
4
0
0
3
0
1
1
0
0
total
0
6
7
0
0
* total from 2 traps per replicate
Page 19
94
68
59
Table 4.
ADB damage assessed at harvest 1993 from insecticide trial at Arthur's Creek,
Victoria.
Treatment
Total fiaiit
% ADB damage
unsprayed
16981
0.353
chlorpyrifos
14953
0.181
fluvalinate
15026
0.193
Queensland:
Sticky traps were not used in the Special Area trial. The number of bugdays accumulated for
each treatment from pink bud to 7 days after complete petal fall in both sites are given in Table
5. Bug numbers at the Baronios site were not significantly different (P > 0.05) for the different
treatments and infestation levels were high for all treatments. There were significant differences
(P < 0.05) between the unsprayed check and all the insecticide tteatments one and three days
after spraying at the Special Area site. At eight days post-freatment bug numbers were
significantly (P < 0.01) higher in the unsprayed freatment than the insecticide freated trees, with
the exception of the azinphos methyl treatment. For the remainder of the flowering period bug
numbers in the Special Area site were not significantly different between treatments.
Bugs were present in sticky traps at Baronios very early and rapidly increased when the flowers
started to open (9-19 days after pink bud), with all treatments accumulating similar total bugdays
by 33 days after pink bud. Damage was higher than in the Victorian site. The results of the early
December assessments are given in Table 6 and harvest results in Tables 7 & 8.
Table 5.
Total bugdays accumulated over the flowering period in the Queensland trials.
Treatment
Total ADB bugdays accumulated
Baronios
Special area
sticky frap
blossom jarring
blossom jarring
trichlorfon
362
681
657
fenthion
432
732
416
azinphos-methyl
415
642
519
chlorpyrifos
389
722
427
fluvalinate
410
758
455
unsprayed
*
*
553
* not included in trial
Page 20
Table 6.
ADB damage recorded early December 1992 in Qld trials.
Treatment
% ADB damage
Baronios
Special Area
trichlorfon
28.2
49
fenthion
33.4
43
azinphos-methyi
29.8
58
chlorpyrifos
33.8
50
fluvalinate
29
46.5
unsprayed
*
63.5
* not included in trial
Table 7.
ADB damage recorded at harvest 1993 in Baronios block, Qld.
Treatment
% ADB damage recorded at Harvest
class 1
class 2
juice
total
trichlorfon
5.86
2.54
0.00
8.40
fenthion
6.04
4.13
0.18
10.35
azinphos-methyi
4.39
2.63
0.10
7.13
chlorpyrifos
4.19
3.50
0.20
7.89
fluvalinate
4.87
3.06
0.15
8.08
Table 8.
ADB damage recorded at Harvest 1993 in Special Area, Qld.
Treatment
%ADB damage recorded at harvest*
class1
cl£iss2
juice
total
trichlorfon
18.70 a
15.07 a
2.02 a
35.80 a
fenthion
13.98 ab
10.25 ab
0.56 be
24.78 be
azinphos-methyi
15.24 ab
11.40ab
0.87 be
27.50 abc
chlorpyrifos
13.51b
5.77 b
0.41c
19.69 c
fluvalinate
14.34 ab
10.30 ab
0.35 c
24.99 be
unsprayed
19.62 ab
12.17 ab
1.38 ab
33.17 ab
' numbers followêd by the same letter in each column are not significantly different (p>0.05)
Page 21
Discussion
Comparison of Table 6 with Tables 7 & 8 suggests that fruit severely damaged by ADB is
preferentially shed by the tree during the mid-season drop, or that minor dimples (which appear
more obvious on small fruitlets) "grow out". Fruitgrowers, however, get their first impression of
ADB damage while assessing the need for hand thinning of fruit (prior to mid-season drop) and
generally grossly over-estimate the amount of damage. Very few growers have accurate records
of the amount of ADB damage recorded at harvest.
The ADB populations experienced at each trial site ranged from very low (Arthur's Creek) to
high (QLD). Chlorpyrifos and Fluvalinate gave the best results of the chemicals tested. There
were no significant differences between Chlorpyrifos and Fluvalinate in any of the trials. This
suggests that Chlorpyrifos would be a suitable choice for prophylactic appUcation at the pink
bud stage but careful monitoring of pest populations will be required so that growers can decide
if additional spraying during bloom is needed. Bower ef al (1993) demonsfrated that apples are
most susceptible to ADB damage in the period from early pink bud to full bloom and the
threshold increases with the number of days elapsed suice pink bud. In seasons with a profracted
flowering period and/or high ADB populations it may be necessary to spray again during bloom.
Chlorpyrifos is not suitable for application while bees are foraging and our study confirmed that
bee deaths can be expected for two days after application (Table 2). Growers facing high ADB
populations during bloom would have to decide between the use of Endosulfan or Fluvalinate
and their choice should depend on the relative importance of mite control in their orchard
compared to potential loss caused by ADB.
The amount of damage sustained by individual trees in each of the trials was highly variable and
demonstrates the difficulty of working with sporadic pests such as ADB. In the Qld "special
area" trial site, for example, none of the treatments showed statistically significant differences to
the untreated trees with regards to class 1 or class 2 finit despite the "best" treatment
(Chlorpyrifos) having 13.51 and 5.77 % damage respectively compared to the untreated having
19.62 and 12.17 % respectively (Table 8). The trials were established to determine the efficacy
of a single application of the freatments. Further work is required to determine the efficacy and
side effects of programs involving Chlorpyrifos applied at pink bud followed by extra
applications of either Endosulfan or Fluvalinate during bloom.
Page 22
TECHNICAL REPORT 4
EVALUATION OF TRAPPING AND BLOSSOM JARRING FOR MONITORING
APPLE DIMPLING BUG (Campylomma liebknechti (GIRAULT)
(HEMIPTERA:MIRIDAE))
F.D PAGE & P.R NIMMO
Granite Belt Horticultural Research Station, Stanthorpe Qld 4380
Aim
To evaluate the various methods for monitoring apple dimpling bug Campylomma liebknechti
(ADB) populations in orchards.
Introduction
The severity of apple dimpling bug invasions and subsequent varies greatly between years and
is fairly unpredictable so reliable methods of monitoring bug activity are important. Pan
traps, white sticky traps and wind-vane traps were tested in comparison with the standard
blossom tapping method in four states initially - New South Wales, Queensland, Western
Australia and Victoria in 1990-1991. The white sticky traps were the most promising so they
were tested against the standard tapping method in the first three states in the next two years.
Materials and Methods
1990-1991
Three different trap types - white sticky plate, pan trap, and wind-vane trap were trialed in
unsprayed apple orchards in Queensland, Western Australia, New South Wales and Victoria.
Trapping was compared with the standard method of blossom jarring. Fifty blossom clusters,
randomly selected on various parts of the tree were jarred several times over a 4L icecream
container or into a 23 cm diameter insect net. Sampling and trap servicing were carried out
thrice weekly during the main blossom period starting at the pink bud stage through to at least
two weeks after petal-fall (twice weekly in NSW).
Page 23
Sampling by blossom jarring (or tapping) was completed during the morning when
temperatures were cooler and the bugs were less active and easier to count. As flowering
progressed, 'blossom clusters' randomly included post petal-fall clusters (except for Western
Australia 1989-90, 1990-91 where flowering clusters were chosen).
Additional traps were placed in other orchards, example - stonefhiits, pears, to see whether the
pattern of build up of ADB was similar district wide.
Samples of bugs were preserved in 70% alcohol and forwarded to Dr M Malipatil, insect
taxonomist. Institute for Horticultural Development, Knoxfield, for specialist identification.
The sex of the bugs was also determined to find out what the usual sex ratio is.
Trap types
Sticky plate traps: In 1990-91 the traps for all sites were made at Orange. They were 20 x 15
cm plywood rectangles (3 ply) painted with titanium oxide gloss white paint and coated with
Bird Tanglefoot®. The traps were similar to those used in the United States of America
(Prokopy 1982). During 1991-93 disposable white plastic plates of similar size and
reflectance were used instead of the plywood traps.
Wind vane traps: The trap is shown in Figure 1. The traps (design by Tayer and Pahner
1972) were mounted at three levels 1.5m, 3.0m and 5.0m on a tower or hail netting structure
and, where possible, the tower was placed in the centre of the trial orchard. The metal vane
oriented the net towards the wind and insects could then be blown into the net and fmally into
ajar of alcohol.
Pan traps: Each pan trap was madefi-omsmall green plastic dishes (approximately 15cm
diameter) which were secured to steel fence posts at a height of 1.5m. The plastic dishes were
supported by wire loops. Pans contained ethylene glycol. At Stanthorpe 50% special
methylated spirits was used instead although extra servicing was required.
Figiire 1.
Wind vane trap
Page 24
Trial layout
A similar grid pattern for trap placement was used in each state, although the grid size and
spacing varied: 6x6, 8x7, 5x5 and 4x8 for Queensland, Victoria, New South Wales and
Western Australia respectively. The sticky plate trap and blossom jarring trees were paired at
each grid point and a pan trap was placed mid-way between the two trees. The white sticky
plate trap was placed on the outside of the canopy at shoulder height and the foliage was
removed for approximately 30 cm around it. It was placed on the opposite side of the tree to
the pan trap to avoid competition between traps.
Cultivars
The apple cultivars varied with each state and some site/cultivar changes were made each year
(Table 1). It was important to see whether the monitoring methods were reliable for different
cultivars. Estimates of the average stages of phenology of the apple trees at each site
throughout the monitoring period were made but stages for individual trial trees were not
recorded.
Table 1
Trap sites and apple cultivars
Year
WA: Stoneville
Qld: Cottonvale
NSW: Bathurst
Hi Early Red Delicious,
Mainly Granny Smith,
Harold Red Delicious,
Granny Smith, Abbas.
Granny Smith, Jonathan
some Delicious
1991/92 Qld: Cottonvale
WA: Stoneville
NSW: Bathurst
Pink Lady, Sundowner,
Jonathan, Red
Harold Red Delicious,
Delicious, Granny
Granny Smith, Jonathan
Gala, Lady Williams
Smith
1992/93 Qld: Applethorpe
WA: Stoneville
NSW: Bathurst
Delicious, Granny
Pink
Lady, Red Fuji,
Red Delicious, Granny
Smith
Sundowner, Gala
Smith, Jonathan
1990/91 Vic: Drouin
only
Mainly Jonathan, a few Golden Delicious and Red Delicious
Qld - Queensland, NSW - New South Wales, WA - Western Australia, Vic - Victoria
1990/91
Fruit damage
Damage by apple dimpling bug was assessed at harvest.
Page 25
Meteorological records
Records were obtained from the nearest weather station for the observation periods at each
site. Records included daily maximum and minimum temperatures, rainfall, windspeed and
direction (9.00 am).
1991-1992
Twenty pairs of trees, each tree of a pair being of the same variety were scattered through an
unsprayed block. Traps were evaluated on several different varieties in three states Queensland, New South Wales and Western Australia. This provided data on the
attractiveness of different varieties to ADB and their susceptibility to damage. One tree per
pair had a disposable white sticky trap (from Pest Management Supply USA) and the other
tree was used for blossom tapping.
All potentially damaging bug species were recorded on traps and taps, not just ADB as
rutherglen bug Nysius vinitor and the brokenbacked bug Taylorilygus pallidulus had been
observed in 1990-91.
Traps were placed at spurburst or pink bud stage following the procedure used in 1990-91.
They were examined thrice weekly until two weeks after complete petal fall (twice weekly in
New South Wales).
When the traps were removed a 2 x 10 cm rectangle in the centre of the trap was counted for
thrips before disposal.
The phenology of each tree was estimated on each sampling occasion using standardised
phenology definitions (Table 2).
A sweep sample of bugs was taken to obtain specialist taxonomic identification of the bug
species to confirm that the dimpling bug was the species attacking apples in each state.
Damage assessments were performed at least once during fruit development (late November,
January) by sampling 50 fruit per tree. At harvest the number of fruit samples per tree was
200 and it was graded according to NSW grade standards.
1. Clean
2. Class 1
-
3. Class 2
-
4. Juice
-
no damage due to ADB
total damage to the finit surface due to ADB fit
within a 5 mm diameter circle.
pronounced dimple or multiple dimples covering
an area greater than a 5 mm diameter circle.
severely dimpled fruit, unsaleable.
Colour photos were used to ensure uniformity of assessments across states.
Page 26
Table 2.
Greentip
Spurburst
Bud separation
Early pink
Pink
Late pink
Bloom
Full bloom
Petal fall
Full petal fall
Post petal fall
Standardised phenology definitions
Green leaves just pushing through bud scales.
Flower buds still clustered together, leaves unfolded away from buds
Flower buds just separated from each other.
First sign of pink visible on flower buds, as sepals just begin to
separate.
Pink colour obvious on most flower buds.
Flower buds expanded and petals pushing outwards. Flowers
not yet open, but the odd early blossom may be out.
Once flowers state opening, bloom is classified as an estimate x
100 of % open, i.e. number flowers x 100 buds + flowers,
nimiber of buds + flowers.
This can be estimated by eye.
The point at which all flowers are open, the peak of floral
display.
Some late buds may not be synchronised with the rest. Full
bloom
is essentially the last point before petal fall commences in
earnest.
Some petal fall may occur on early flowers at or just before fiiU
bloom.
As with bloom, petal fall can be classified as an estimate of the
flowers that have lost their petals.
The point at which all flowers have lost their petals, apart from
the odd late blooms that may occxir on laterals etcetera.
After full petal fall the phenology can be classified as the
number of days after petal fall, i.e. petal fall + 3 days, etcetera
Statistical analyses
The correlations between tap catch and temperature and trap catch and temperature were
calculated for each site. The rainfall data are presented graphically. Multiple regression
analysis was used to determine the effect on the response variate bugs per day for different
factors, with the fitted terms including constant + traps + variety + columns + taps,
phenology, and their interactions. A poisson distribution was used and a log link fiinction.
Predictions which were then made from the regression model are fitted values formed on the
state of the response variable adjusted with respect to some factors, for example, row, variety
and columns, where marginal weights based on counts of factor levels in the data were used.
The predictions were standardised by averaging over the levels of some factors. The standard
errors for the predicted values of bugs per day for tap and frap samples at different stages of
phenology are approximate since the model is non-linear.
Page 27
1992-1993
Similar procedures were followed to those used in 1991-92. In Queensland, two pre-bloom
insecticide trials were combined with the trap/tap comparisons. In Trial 1, a randomised
block design was used with a plot size of two trees and five replicates. The following
insecticides were tested in both trials:
1.
2.
3.
4.
5.
trichlorphon
fenthion
azinphos-methyl
chlorpyrifos
fluvalinate
0.05%
0.05%
0.05%
0.05%
0.005%
A randomised block design was also used for Trial 2 (6 treatments x 5 replicates). A check
(unsprayed) treatment was incorporated in Trial 2, but not Trial 1. The apple cultivars were
Granny Smith for Trial 1 and Red Delicious for Trial 2.
Results
New South Wales
1990-1991
Numbers of ADB were quite low throughout the trapping period (Figure 2).The blossom
tapping and sticky traps both detected low numbers of ADB on 8 October in the Delicious
and Granny Smith cultivars. No ADB were caught in sticky traps on the Jonathan trees
which were at 30% bloom compared with three bugs in the blossom taps. From then on no
further ADB were caught on any sticky traps until 16-22 days after full bloom, 1-5 November
,which varied for each cultivar (Figure 2).The blossom tapping detected similar numbers of
bugs on each cultivar on each sampling date from 8 October onwards.
Predictions from the regression analysis for bugs per day in trap and tap samples are shown
for the different stages of phenology (Figure 3 ).The blossom taps were far superior to the
sticky traps. The sticky traps did detect bug activity during pink to late pink and at these
stages there were not large differences in predicted ADB numbers between the two methods
:in contrast to the much higher numbers predicted for the blossom tapping from fiill bloom to
16 days post bloom,
Page 28
£6
1991-92
35r
1990-91
JB 4
I'
E
2 2
Eartypink
Ute'pink
Bloom
Nitalfell
Pf*1
Eariypii*
fT + 14
Utepink
Eariypk*
PeMlfaB
Btoom
PF+1
PF + 7
1992-93
Eartypink
Figure 2.
Latepink
Soocn
Ptetalfad
PF + 7
PF+14
Mean numbers of ADB taken on sticky traps and in blossom taps
at various phenology stages, Bathurst NSW 1990-93
Blossom taps
Sticky traps
cpink
pink
Ipiiik
rullblcKini
tbfio'J
iblt:Di6
IblSiolO
cpink
pink
Ipink
Tullbioom
fb5io9
Phcnolog)' Slagc
I I'mliclion OSld Enor
. • Prediaion aStd Error
Figure 3.
Predictions from multiple regression analysis for numbers of ADB
per day in trap and tap samples at Bathurst NSW 1990-91
Page 29
1b[ltoi6
fblSioIb
Despite the low ADB populations damage at harvest due to ADB ranged from 2.0 -7.5 % for
the delicious cultivar and from 1.8-7.2 % for the Granny Smith cultivar(Table 3). Damage to
the Jonathan cultivar was minor.
Rep
Al
A2
A3
A4
A5
A6
A7
A8
A9
AlO
All
A12
A13
A14
A15
Delicious
%
No.
downgraded
2
647
220
7.3
298
3
5.7
531
3.6
613
2
689
294
7.5
623
2.7
603
5.1
554
0.6
541
0.7
377
0.5
0.4
521
513
0.6
578
0.3
Table 3.
Rep
Bl
B2
B3
B4
B5
B6
B7
B8
B9
BIO
Bll
B12
B13
B14
B15
Jonathan
No.
%
downgraded
329
0.3
0.4
473
525
0.4
121
4.1
145
0.7
289
0.3
526
0
311
0.3
592
0.3
337
0.3
482
0.2
0
367
611
0
503
0
327
0
Rep
CI
C2
C3
C4
C5
C6
C7
C8
C9
CIO
Cll
C12
C13
C14
C15
Granny Smith
No.
%
downgraded
558
1.8
496
1.6
538
4.1
6.4
533
596
4.7
612
4.2
547
4.9
514
7.2
221
3.6
532
0
371
0.3
552
0.5
477
0.6
467
1.7
460
1.3
Fruit downgrading due to ADB at harvest, Bathurst NSW 1990-91
1991-1992
Low numbers of ADB were taken in blossom taps and the sticky traps during the early pink
to early bloom stage for Jonathan , Delicious, and Granny Smith cultivars. Higher numbers
were recorded on traps than in taps during the main bloom period for the Delicious cultivar
(Figure 3). Bug numbers increased markedly for both methods during bloom. Once petal
fall was close to 100%, the numbers in the taps were much higher than those caught in the
traps. Bug numbers continued to increase in the taps until 14-16 days after petal for Jonathan
and Delicious , whereas for Granny Smith trap numbers were higher during the petal fall to 16
days post petal fall period than during bloom ,but were much lower than those in the taps.
Thrips numbers on the Granny Smith cultivar were moderate during early bud separation to
pink bud stage -24 per 20 sq cm trap sample increasing to 32 atfiiUbloom, peaking at 145 at
petal fall with moderate numbers remaining on all varieties until 8 November (Table 4).
Predictions from the multiple regression analysis for bugs per day in trap and tap samples are
shown for the different stages (Figure 4). Both monitoring methods predicted similar
numbers of bugs from bud separation to early pink stage but for most of flowering, petal fall,
and post petal fall, the predicted number for taps were much greater than for the traps.
Page 30
Table4.
Mean numbers of plague thrips, Bathurst NSW 1991-92
Phenology
Early pink
Late pink
Full bloom
Petal fall
Petal fall + 7
Petal fall + 14
Jonathan
24.7
66.7
41.4
160.1
37.9
39.2
Delicious
30.6
56.3
41.4
153.2
36.2
23.9
Granny Smith
23.8
67.8
31.9
144.6
29.2
22.8
Total fruit damage per tree ranged from 11-28% for Delicious to 11-23 % for Granny Smith
(Table 5)
Figure 4.
Predictions from multiple regression analysis for numbers of ADB per
day in trap and tap samples, Bathurst NSW 1991-92
Sticky traps
Blossom taps
FB
PFlOoy.
Plicnulug}- Stage
[•Prediction aStd Emjrj
FB
PF100%
I'ticiiulug}' Sl:tj;c
I Prediction D Sid Error I
Page 31
Table 5.
Fruit damage and downgrading at harvest caused by ADB,
Bathurst NSW 1991-92
Delicious
Rep
Al
A2
A3
A4
A5
A6
A7
A8
A9
AlO
All
A12
A13
A14
A15
%
%
damage
downgrad
ed
2
7.3
3
5.7
3.6
2
7.5
2.7
5.1
0.6
0.7
0.5
0.4
0.6
0.3
12.7
10.3
24.7
9.2
5.6
15.2
13.1
4.3
28.2
0.4
1.3
0.4
0
0.5
0.5
Granny Smith
Jonathan
Rep
Bl
B2
B3
B4
B5
B6
B7
B8
B9
BIO
Bll
B12
B13
B14
B15
%
%
damage
downgrade
d
0.3
0.4
0.4
4.1
0.7
0.3
0
0.3
0.3
0.3
0.2
0
0
0
0
0
0.8
0.3
1.2
0.5
1
0
0
0
0.3
0
0
0.4
0
0
Rep
CI
C2
C3
C4
C5
C6
C7
C8
C9
CIO
Cll
C12
C13
C14
C15
%
%
damage
downgrad
d
1.8
1.6
4.1
6.4
4.7
4.2
4.9
7.2
3.6
0
0.3
0.5
0.6
1.7
1.3 !
14.5
11.6
23.1
14.7
12
11.4
22.9
15.1
16
3
3.3
2.9
3.4
1.3
3.1
1992-1993
As in the previous year , low numbers of ADB taken in taps and traps during early pink to
early bloom were comparable (Figure 2 ). During bloom the numbers taken in the taps were
much higher than numbers caught on the traps for all cultivars . Numbers of bugs taken in the
taps continued to increeise as petal fall advanced but started to decline by 11 days post
petal fall (Table 6) Numbers taken in taps peaked approximately five days after petal fall
(between 30 October and 2 November) for all cultivars. Then tap catches were still
correspondingly high for the Delicious and Jonathan cultivars at this stage but the trap catch
for Granny Smith had peaked earlier -69 ADB on 26 October (Table 6). However this
cultivar reached fiill bloom several days earlier than the other cultivars.
Date
2.10
9.10
16.10
23.10
30.10
6.11
Table 6.
Taps
4
34
119
163
162
144
Delicious
Traps
1
15
74
61
100
67
Taps
4
19
84
151
365
275
Jonathan
Traps
2
16
35
43
108
93
Taps
6
50
171
360
274
137
Granny Smith
Traps
4
44
81
60
120
66
Total number of ADB collected from sticky traps and blossom
taps, Bathurst 1992/93.
Page 32
Predictions from the multiple regression analysis for bugs per day in tap and trap samples are
shown in (Figure 5). As in 1991 the predictions for the pink to late pink stage were similar for
blossom taps and sticky traps. In 1992 this also applied to the bud separation stage. Predicted
numbers for sticky traps were consistently lower from then on (Figure 5) although there was
about a four fold increase in numbers from fiiU bloom to 16-18 days post petal fall for the
traps and a seven fold increase in predicted numbers for taps from fiiU bloom to 16-18 days
after petal fall (Figure 5).
Sticky traps
Blossom taps
lu.op
i y
III
s.oo
e 111 u
111 M 1 y
6.00
.4.00
• 11 I I I 11
2.00
0.00
LP
BSOy.
FB
PnOW
PFIOOW
PF2105
L^,_^jL 1 • 1 . 1 : 1 : I , U j
LP
PF7lo9 PFUloli
B50%
rF70%
PFIOpV.
PF2io5
PF7to9 PFiUoES
[•Prediction OSui Enorj
jel'Tv-diction DSlil EmjrJ
Figure 5.
FB
rbcaclog}- Stage
PUcnoIogy Singe
per day in trap and tap samples, Bathurst, NSW 1992/93.
Damage was between 10.2-20.8 %for the Delicious cultivar and much higher for Granny
Smith -10..7- 44.4%(Table 7). The level of damage to Jonathan was about one percent.
Delicious
Rep
Al
A2
A3
A4
A5
A6
A7
A8
A9
AlO
All
A12
A13
A14
A15
Table 7.
Granny Smith
Jonathan
%
%
damage
17.2
15.6
20.8
10.2
13.5
11.4
16.7
downgrad
ed
13
11.3
16.1
7.3
11.3
8
11
12.2
7.1
14.9
6.2
7.1
9.2
7.3
8.8
4.7
11
3.4
4.9
6.6
4.8
Rep
Bl
B2
B3
B4
B5
B6
B7
B8
B9
BIO
Bll
B12
B13
B14
B15
%
%
damage
3.1
downgrad
ed
2.3
1.6
1.8
0
3.1
1.4
0.5
2.5
1.4
1.4
1.6
0.6
0.8
0
0.8
1.1
0
1.7
1.2
0.5
1.3
0.6
0.9
1.6
0
0.8
0
Rep
CI
C2
C3
C4
C5
C6
C7
C8
C9
CIO
Cll
C12
C13
C14
C15
%
%
damage
downgraded
10.7
16.9
20.2
18.6
20.4
23.1
29.7
38.8
44.4
11.2
4.9
11.1
13.8
11.7
10
16.5
22.2
25.6
31.8
7.7
13
16.9
24.4
23.2
8.2
9.6
14.9
15.5
Percent damage caused by ADB and percent downgrading at
harvest Bathurst NSW 1992/93.
Page 33
Weather Effects
1990-1993
There was no consistent effect of weather on bug numbers .Maximum temperatures during
flowering (Figure 6) were usually warm enough for bug activity and numerous observations
have shown that ADB wiih stand sub zero conditions. Rainfall does not appear to reduce bug
numbers once they have moved into an orchard ,although blossom tapping was not possible
on very wet days. On 1 November 1991 there was a big increase in bug numbers compared
v^th the previous day. This may have been associated with the change in wind direction from
hot NNW to ENE despite the sudden drop in temperatures of 12 degrees for the maximum.
The effects may also be confounded with stage of phenology, but observations in Queensland
and Western Australia have shown that populations can increase suddenly following the
movement of fronts and changes in vdnd direction.
Queensland
1990-1991
The nvimbers of apple dimpling bugs taken from pan traps , sticky traps , and blossom taps
(net) are shown in (Figure 7) . Low numbers of bugs were taken during the first week at pink
(Figures 7) bud to early bloom stage, with numbers peaking at about full bloom .The
variation in the pattern of distribution of ADB over time is shown by pattern analysis (Figure
8).
12/10
I Pan
I<)/IO
I Plate
26/10
ms Net
Net counts have been divided by ttie
number of samples and multiplied by 3
Figure 7.
Number of ADB taken per week in taps and traps , Cottonvale
Qld
1990-91
Page 34
Figure 6.
!
Maximum and minimum temperatures for Bathurst NSW
1990-93
IS
Page 35
The windvane traps did not trap any ADB but some Rutherglen bugs Nysius vinitor were
trapped. The sticky trap and tap samples both detected low numbers of ADB during pink bud
to early flowering . Greater numbers of ADB were taken in the blossom taps than on the
sticky traps during flowering. Sticky trap catch increased following petal fall and actually
exceeded the tap catch in early to mid November.
Low numbers of brokenbacked mirid bug Taylorilygus pallidulus were taken on traps and in
taps throughout the sampling period, commencing in the first week. The predatory bug
Germalus sp. was also taken occasionally in blossom taps. Weather data are presented in
Figure 9) . One weather factor which was noticeable was the slight increase in the
numbers of ADB and the first observations of brokenbacked bugs foUovdng the movement
of a frontal system through the district with resulting north to north-westerly winds. Similar
increases in numbers of ADB occurred in other orchard sites in the district.
Predictions from multiple regression analysis for bugs per day in tap and frap samples are
shown for the sampling dates(3 times per week) for six weeks of observations. The
predictions show that blossom tapping always resulted in higher numbers of ADB, although
the stickyti-apsdid detect bugs during early flowering in early October (Figure 10). Once
flowering was completed (stagel 1, Figure 10) the predicted numbers of bugs increased
dramatically for both trap and tap samples but the tap numbers were much higher.
35
20Sep
Figure 9.
24Sep
-i
16Oct
1 1 1 1 h—i22Oct
-I—(—\—I—(—I—\~
26Od
1Nov
Maximum and minimum temperatures Applethorpe, Qld, 1990/91
This was a season in which severe drought conditions prevailed so both fmii quality and
quantity suffered in tiiis dryland orchard. A lot of fiaiit shedding occurred ,and later when rain
did occur the fiiiit was of poor quality due to splitting ,and with severe russetting. Economic
damage by apple dimpling bug was present ,as expected with the high numbers of bugs .
Page 36
Figure 10.
per day in trap and tap samples, Cottonvale Qld 1990-91
Blossom taps
Sticky traps
1991-1992
B
9
10
11
12
13
14
IS
Sticky trap data and blossom tap data are shown in Figure 11 and numbers of plague thrips
per trap sub sample are shown in Figure 12. Thrips numbers peaked when trees of all
varieties were mostly in full bloom on 18 (Figure 12) at a mean of 72 thrips per 20 sq.cm.
sample for the 20 traps and fell rapidly post -flowering during November to 17 per sample.
Sticky trap catches of ADB were quite high during flowering and remained high following
100 percent petal fall. The blossom tap numbers were lower and declined during post-petal
fall more than for the sticky traps (Figure 11). However sticky trap data accimiulated over 23 days compared with the result from blossom tapping for one morning . Numbers of other
bugs present were low .Germalus spp. (Lygaeidae ) were taken in blossom taps from 18-30
October but usually only one per 50 blossom taps. Low numbers of Campylomma_spp.
nymphs were taken in early November as well as the occasional cotton seed bug Oxycarenus
luctuosus, and the Rutherglen Nysius vinitor .
Page 37
16
Figure 8.
Pattern analysis of the distribution of ADB over time, Cottonvale
QM
Patters soslysis of dislrOiiilHii] of ADB in srchanl at fuO bloom .CottonvalcOld.
,l«-220tt,199S
.^ - Fatterm saalysia of distribotion of ADB in orchard at 1 week isffer foil bloom
,Cottaiavale,Qid. ,23-2$OcL4mi
v4
. Fsttem saaiysb of distribiitioa of AJ>B ia orchard at 2 weeks after fun bloom
ô«toiiTa!e,QId. 30ct-5Noy,19S«
Page 38
. Patters analyiis of distribntioa of ADB ia orchard at 3 weeks after faU bloom
. êttoH«le,QM. ^ 1 2 NoT,19S0
Figure 11.
Sticky trap catch and blossom tap catch, Cottonvale Qld 1991-92
Sample îpe
7
M
\fe 21 JS^ 30
October
4-
8
^3
tS 33
November
1500
11
18
25
8
October
Figure 12.
15
22
M ovember
Number of thrips trapped per week on sticky traps at Cottonvale
Qld 1991-92
Page 39
The comparison of damage to fhiit for different numbers of ADB is given in Table 8. Fruit
damage was quite variable within each variety.
Table 8.
Rep.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Total ADB numbers, bug numbers and percentage damage in
January 1992, on blossom tap and sticky trap trees, Cottonvale
Queensland
Variety
Tap
Trap
Del
Del
Del
Del
Del
Del
Del
Del
Del
Del
Jon
Jon
Jon
Jon
Jon
Jon
Jon
Jon
Jon
Jon
Jon
Jon
Del
GS
GS
GS
GS
GS
Jon
GS
Jon
Jon
Del
Del
Del
Jon
Del
Del
Del
Del
Bug numbers
Tap
Trap
29
28
32
29
24
37
14
19
38
33
24
18
33
28
18
19
11
16
12
16
9
19
14
30
36
19
20
23
15
22
19
21
19
19
21
15
26
28
19
15
% fiuit damage
Tap
Trap
44
12
20
56
16
20
24
16
12
32
0
4
4
0
0
0
0
0
0
04
0
0
0
4
12
28
0
0
16
8
4
0
8
28
4
8
12
0
Temperature data are shown in Figure 13. There was no consistent relationship between
maximum and minimum temperatures.
Page 40
Figure 13.
Maximum and minimum temperatures Applethorpe, Queensland
1991-92
Predictions from multiple regression analysis for bugs per day in tap and trap samples are
shown for the different phenological stages (Figure 14). The predicted results for tap and trap
samples show a rather similar pattern but bug numbers were usually higher for taps compared
with traps. At full bloom the predicted catches were almost identical. Between 100 percent
petal fall and 2 to 5 days after petal fall the blossom tap catches were higher than the sticky
trap catches. From 16 to 20 days post petal fall and after 21 days post petal fall, higher ADB
numbers were predicted for sticky trap catch compared with blossom catch.
The results for fruit damage are given in Table 8 for the January assessment. The extremely
bad drought in this dryland orchard resulted in a poor crop. A hail storm in December, and
russetting due to other causes made assessments difficult. Damage was quite variable, with
Jonathan suffering only slight damage (TableS). A harvest assessment on a few Granny
Smith trees confirmed that few apples were juice grade as a result of ADB damage, or even
number 2 grade, confirming that most apples only had one dimple.
Page 41
Figure 14.
per day in trap and tap samples, Cottonvale Qld 1990-91
Sticky traps
pinkbud
balloon
npWCTop
Blossom taps
peialll
pinkbud
ballotHi
flimi-TPp
pcialll
sAvolIfrt
1992-1993
The fruit damage results for tap and trap are shown in Table 8. The very early pink bud stage
application of several different insecticide treatments did not protect the crop adequately as
bug numbers increased rapidly a week later. The damage is unacceptable commercially as it
represents a severe economic loss (Table 8), with mean bugdays ranging from 362 to 450 for
frap trees and 632 to 758 for tap frees (Table 9), this is not surprising. Temperature data are
shown in Figure 15.
Table 9.
Number of bugdays for infestations of ADB during pink bud stage
to petal fall + 7 days, Applethorpe, Qld 1992-93
Treatment
trichlorphon
fenthion
azinphos-methyl
chlorpyrifos
fluvalinate
Mean bugdays (frap)
362
436
415
389
450
Page 42
Mean bugdays (tap)
681
632
692
722
758
Figure 15.
Maximum and minimum temperatures Applethorpe, Qld 1992-93
Western Australia
1990-1991
Numbers of ADB taken on sticky traps and blossom taps at the Stoneville Research Station
were quite low .The blossom tap sampling yielded the greatest number of bugs throughout the
eight week monitoring period (8 October-26 November) . The sticky traps caught bugs during
the pink bud stage when bug numbers were similar to those taken from blossom tapping.
Fewer bugs were caught in the pan traps and nil in the windvane traps .
The pan traps caught predominantly male ADB (66 percent of the catch). On many sampling
dates the percentages of males and females taken from trap and tap samples were similar about 50 percent. The highest number of bugs was taken on 5 November- a total of 137 for 32
blossom tap samples compared with 88 for sticky traps, and 63 for the pan traps. These
numbers were almost double those taken on 2 November. Maximum and minimum
temperatures were similar on both dates, but wind direction had changed from ENE to BSE.
The sticky traps regularly caught low numbers of larger mind bugs and were much more
efficient at detecting these than other methods.
Page 43
Temperatures varied considerably during spring in Westem Australia but usually the
minimum temperatures during November at Stoneville were above 10 degrees C with daily
maximum temperatures ranging from 21.5 to 33.5 degrees C (Figure 16) . Sfrong weather
fronts are a common feature of this area with successions of high pressure and low pressure
systems moving across (Figure 17). Bug numbers tended to increase when wind direction
changed to easterly (SE to NE).
Figure 16.
Maximum and minimum temperatures Stoneville Research
Station, WA 1990-91
\
\
20Sep
24Sep
16Ocl
Page 44
22Ocl
26Od
1Nov
Figure 17.
A typical weather chart for WA during spring
RMC MEIBOUKNC
MSI *NAIVSIS/
lSSU€0O«SS C M T l B S^P I 9 i l
.///
i«*l« 'H l*SI — HOURS
1991-1992
Flowering was very uneven due to inadequate chilling .The approximate stages of phenology
were: pink -1 November, late pink - 4 November, full bloom 11 November, petal fall-15
November. During the bud separation to pink bud stage , the traps and blossom taps yielded
similar numbers of ADB (Figure 18). The blossom tap catches were much higher than those
for the sticky traps from full bloom to 9 days post petal fall, when numbers declined rapidly
in tap catches. The blossom tap catch data during late November would be somewhat inflated
as only blossom clusters with petals remaining were samples. Number on sticky traps
declined rapidly between 2 and 9 December.
Figure 18.
ADB found on traps and in blossom taps Stoneville Research
Station, WA 1991-92
21 Ocl
28 Oct
4 Nov
11 Nov
18 Nov
2 Dec
9 Dec
Page 45
Thrips were at a maximum on 21 October 1991-50 to 80 per 20 sq. cm trap sample during
pink bud to early bloom (Figure 19). Similar numbers occurred on each cultivar. Predictions
from multiple regression analysis for bugs per day in tap and trap samples are shown for the
weeks during flowering and post flowering (Figure 20). As flowering was uneven it was not
possible to use the phenological stages, but phenology was similar for each cultivar as there
was much variation from tree to tree.
Figure 19.
Total number of thrips collected from 10 white sticky traps at
Stoneville Research Station, WA 1991-92
100
80
Pink Lady
Sundowner
Lady Williams
Gala
60
E^
z a.
40-
20
1
1
21 Oct
28 Oct
4 Nov
11 Nov
18 Nov
Date
Figure 20.
Predictions from the multiple regression analysis for numbers of
ADB per day in trap and tap samples, Stoneville Research Station, WA
1991-92
Sticky traps
Blossom taps
10
PhenolDgj Stage
• Prediction DScd Eirar
iHPrcdioion DSUIEITOT
Page 46
II
12
The percentage of damaged fruit for each cultivar is given in Table 10. There was a big
variation in the percentage offiruitdamage for the different cultivars, and with the exception
of Sundowner, damage levels were the same in January as in November.
Table 10.
Percentage of fruit damaged (mean, s.d) by ADB, Stoneville
Research Station, WA 1991-92
Variety
Pink Lady
Lady William
Gala
Sundowner
15.1.92
20.4 ± 3.7
13.6 ± 2.9
6.4+ 2.2
2.8 ± 1.3
12.11.91
19.6 ±2.7
14.8+ 4.1
7.6 ± 2.7
6.4 ± 1.7
1992-1993
Bug numbers were high during this season . The numbers taken on sticky traps were much
lower than those taken from blossom tapping (Figure 21) The traps detected ADB activity at
the pink bud stage and the overall pattern of activity during the sampling period was similar to
that for blossom tapping .
160
140
J.
120
Q
<
100
80
Si
E
-
/
/ \
Sticky trap
Blossom tap
j
\/
/
\
i
\
i
\
V A
60
- y\
40
/'
3
\
L_L_p*'*^
\
/
20
0
-^-C:i=?</
8 1 0 1 2 1 5 1 7 1 9 2 2 24 26 29 31 2 5 7 9 12141619 2 1 2 3 26
October
Figure 21.
November
ADB numbers taken on sticky traps and in blossom taps,
Research Station, WA 1992-93
Predictions from multiple regression analysis for bugs per day in tap and frap samples are
shown for the different stages of phenology (Figure 22). The patterns for tap and trap catch
correspond quite well although trap numbers are much lower. Predicted numbers increased at
flowering in the tap samples but stayed the same as in the pink bud-balloon stages in the trap
samples.
Page 47
Figure 22.
Predictions from the multiple regression analysis for numbers of
ADB per day in trap and tap samples, Stoneville Research Station, WA
1992-93
Sticky traps
Blossom taps
25.00
S
20.00
J
a
15.00
10.00
11
pinkbud
petiUfl
pinkbud
balloon
Duwcrop
petalfl
swoilfn
PltcnwIuK}' Slage
• I'rctiiciioii Q S U I Error.
• Prcdiclion o S t d Error
The percentage damage to apples when sampled in early December, and the percentage at
harvest are given in Table 11. Damage categories are 1 = classl, 2 = class 2, and 3 = juice.
The percentage of damaged fruit for all cultivars was quite high in December and this was to
be expected given that the bug numbers were high, exceeding the economic injury level of
250 bugdays by several times (Table 11). The damage at harvest showed a much greater
amount of variation, but all cultivars suffered substantial economic damage .
Variety
Damage
at 2.12.92
Damage at harvest
No.fruit
Pink Lady
Gala
Sundowner
Red Fuji
Fuji
53/16
Table 11.
72
76
86
81
73
62
411
1222
1221
1177
1139
1133
1
2
125
150
75
47
48
2
19
436
270
436
177
58
3
19
24
5
60
32
0
Percentage of fruit damaged by ADB, Stoneville Research Station
WA 1992-93
Page 48
% damage
9.7
47.8
34.8
48.5
22.5
9.4
Victoria
1990-1991
Populations of ADB were quite low (Table 12). The sticky traps yielded the greatest number
of bugs - a total of 64 compared with 48 for the pan traps and 37 for the blossom taps. Sticky
traps and pan traps were as effective as blossom tapping in detecting the presence of apple
dimpling bug in the pink bud to early flowering stage . The wind vane traps did not catch
ADB. Larger numbers of Rutherglen bug Nysius vinitor were taken compared with the
numbers of ADB.
Table 12. Tap and trap data ADB Drouin, Victoria 1990-91
Date
Numbers of ADB
Tap
Pan
Trap
25 Sep.
28 Sep.
02 Oct.
05 Oct.
O90ct.
120ct.
16 Oct.
190ct.
23 Oct.
260ct.
30 Oct.
02 Nov.
06 Nov.
09Nov.
0
0
0
2
0
3
8
6
4
6
8
0
0
0
0
0
0
1
3
1
10
4
11
8
7
15
3
1
0
1
0
0
0
0
3
0
0
6
8
20
5
5
TOTAL
37
64
48
Discussion
The standard method of blossom tapping is the most reliable method of monitoring for ADB.
It usually yielded much higher numbers of ADB than the white sticky traps (Figures. 2,3, 7,
18). Sticky traps are in place continuously but are more difFicuh to service as many other
non-target insects are caught and the dimpling bugs can be difficult to see. Tapping is a more
direct method of sampling whereas the sticky traps may trap bugs which are just moving
through the orchard.
Page 49
The white sticky traps were as reliable as blossom tapping for detecting the activity of ADB,
Rutherglen bugs, and the mirid bug Creontiades pacificus during bud separation to pink bud
stage. Numbers of ADB taken during the early stage of flowering were generally low for both
methods in all states.
If there had been a consistent relationship between tap catch and trap catch it may have been
possible to use a conversion factor to estimate tap catch from trap data. This may be possible
for Westem Australia where there is a similarity in the pattern of ADB activity when
measured by both methods (Figures. 18,20,21,22).
There is a big variation in the different environments in climatic types (max. min.
temperatures, wind, rainfall), orchard design and cultural practices between the different
states, so there are many factors affecting the build up of ADB populations in different states.
However the stage of phenology appears to be of major importance as ADB numbers are
usually much higher at full bloom than in earlier stages of flowering. Once large numbers of
ADB have moved into orchards the population remains high for up to several weeks post
petal-fall. This occurred in three states (Figures. 2,3, 5,7,10,18,21,22). In unsprayed
orchards nymphs were found in late November - early December as a result of egg laying in
foliage.
There was no consistent effect of temperature on bug populations but bugs although present
are less active on the trees on cool mornings, so blossom tapping is best done in the morning
when the bugs do not fly as quickly. Weather conditions do have an effect on movement of
bugs into orchards. At Cottonvale, Queensland in 1993, bug numbers rose rapidly during 8 to
15 October in both traps and tap samples following the movement of a low pressure system
through the district and a change to westerly winds.
A five-fold increase in bug numbers was recorded in three stonefruit orchards during the same
period of time (separate project - Final Report to HRDC Project FR121). Movement into
orchards also occurs from local populations which breed on natives and introduced host plant
species as records show that ADB survived during winter at Stanthorpe and Bathurst, but
usually in low mmibers. Similarly at Bathurst NSW and at Stoneville WA, weather fronts and
changes in wind direction can result in sudden increases in bug numbers. In Westem
Australia numbers increase when easterly winds occur.
Pattern analyses showed that bug movements into orchards were quite rapid (Figure. 8) so
there was little chance of using perimeter spraying to adequately protect orchards.
The results have confirmed the economic injury studies of Bower et al. (1993) and the fiirther
studies of susceptibility of apples to damage by ADB at different stages of flower phenology
(see separate section of this report). The fruit damage results showed that the economic injury
level for ADB is quite low so carefial monitoring for bugs during the blossom period is vital if
growers wish to prevent serious financial losses due to downgrading.
Page 50
TECHNICAL REPORT 5
SUSCEPTIBILITY OF STAGES OF APPLE DEVELOPMENT TO INJURY FROM
APPLE DIMPLING BUG (Campylomma liebknechti (Girault)) (HEMIPTERA:
MIRIDAE) FROM BUD SEPARATION TO FRUIT SET
C. C. BOWER' AND A. HATELY'
1. NSW Agriculture, Kite St. Orange, NSW 2800.
2. Orange Agricultural Institute, Forest Rd. Orange, NSW 2800.
Introduction
ADB damage on apple is purely cosmetic, affecting only the appearance of the fruit, not its
goodness or keeping qualities. Damage ranges from small areas of russet to severe distortion,
especially if the fruit has been stung several times. Minor blemishes do not result in
downgrading, but fruit with large malformations are suitable only for juicing. ADB can cause
relatively high levels of damage to Delicious and Granny Smith varieties in some years.
Aim
The aim of these trials was to determine at which stages of development the fruit are
susceptible to ADB attack and to compare the severity of the damage caused at different
stages of fruit development. This was carried out over three years through a series of
progressive experiments, with each year's experiments taking into account and responding to
the previous year's results. As a result of the 1990/91 findings, in 1991/92 the role of thrips in
causing damage to fruit had to be determined so that ADB damage could be isolated. The
1992/93 season was used to establish more precisely the period of susceptibility for ADB
damage and fiirther compare the effects of ADB and thrips damage to fruit during blossoming.
The trial site
This trial was conducted at NSW Agriculture's Bathurst Agricultural Research Station located
on the Central Tablelands of NSW (Lat. 33° 26' S. Long. 149° 34' E, elevation 713.0m above
sea level). The average maximum summer temperature (November to March) in Bathurst is
21.TC, the average minimum 11.6°C. The mean winter temperature range is 0°C to 12°C
with frosts occurring from April to early November. The mean aimual rainfall is 630 mm,
with the summer months the wettest (Bureau of Meteorology, records of Stn. 63005 Bathurst
Agricultural Research Station, NSW).
Page 51
Planted in 1958/59 the trial orchard was a contoured block of approximately two acres that
sloped towards the east. Immediately surrounding the orchard were paddocks laid to general
pasture, with the exception that 20 m to the south was an area of remanent bush land. The
orchard's ground-cover was controlled as per commercial practice, ie. with herbicide strips
within the tree rows and central mowing. During dry periods the trees were irrigated at a rate
of 8L / hour, for 4 hours, 3 times per week (Monday, Wednesday and Friday).
The orchard (H block) comprised eight rows of the cultivar Granny Smith with Red Jonathan
pollinators and a partial ninth row filling in the space due to the sloping contour (Figure 1 )•
The orchard's trees were open pruned to a vase shape and were an average height of 4.5m.
Planting distances were 7m between rows and 7m between trees.
1990/91 SEASON
Exclusion caging
ADB was excluded from blossom clusters for varying lengths of time by enclosing them in
ADB-proof cages. The cages were cylindrical sleeves (20 cm X 12 cm) constructed from
plastic quarantine mesh. Each sleeve was fitted with a cloth collar and drawstring at the neck
to seal the cage around the branch.
Twenty pairs (A and B), of Granny Smith trees were selected and twelve cages were placed
over clusters of flower buds on one tree (A) from each pair (Figure 1 ). The cages were
deployed on 25.9.90, at which time the trees were at spurburst and removed on 9.11.90. The
trees were immediately sprayed with azinphos-methyl after cage removal to kill all ADB and
prevent fixrther damage. Sprays were repeated at 3-weekly intervals thereafter. At 3-4 day
intervals during the trial period, one cage was moved from the cluster on tree A to a similar
cluster on tree B. All the clusters were tagged and numbered individually. A third group of
clusters remained caged throughout the trial period as a control. The flowers within cages
were hand-pollinated with fresh Jonathan blossom on 10.10.90. At each cage change the tree
phenology was recorded, based on a mean visual assessment of the orchard. The phenology
classifications were:
GT
Greentip- leaves just pushing through bud scales.
SB
Spurburst - flower buds are still clustered close together with the leaves
unfolding away from the buds.
BS
Bud separation - flower buds move apart from each other
EP
Early pink - first sign of pink visible on most flower buds.
P
Pink - pink colour obvious on most flower buds.
LP
Late pink - flower buds expanded and petals pushing outwards.
F
Full bloom - flowers opening, peak floral display.
PF
Petal fall - nearly all petals fallen from flowers
PF+
Full bloom plus number of days after full bloom.
Page 52
Figure 1.
Exclusion trial trees and background population tap trees
(H Block, Bathurst A.R.S) 1990-1991
+
N
3B o
2B
o
2A
3Alo
o
o
lOB
+ 16B
lOA
o 30
2 0
6 0 IIB
4B
4AL£
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o
o
•
o
SB
+
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o
17A
16A o 15B
nAL2.
+
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HA
100
o'
o
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o
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o
o
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o
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0
4
lA
0
7B o
8B o
o
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+
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8A o
+
o
®5®
Granny Smith
Jonathan
Missing tree
Cage tree
Tap tree
o
g 02OB
12G
20A| o.
o
o
+
Q
Q
Fruit was assessed for damage by ADB in November (12.11.90) and at harvest (3.4.91). At
both assessments the number of ADB "stings" was recorded. At harvest an overall
classification of market quality was assigned to eachfroxit.The damage was classified as:
Page 53
Clean
- no damage due to ADB.
Class 1
- total damage to the fruit surfrice due to ADB fits within a 5 mm
diameter circle.
Class 2
- pronounced dimple or multiple dimples covering an area greater than
a 5 mm diameter circle.
Juice
- severely dimpled fruit, unsaleable.
Fruit classified as Class 2 or Juice is considered to be downgraded.
The orchard's general 'in tree' ADB population was monitored twice weekly. Fifty blossom
clusters were tapped, by hand over a 4 L white plastic container, on each of ten sample trees
and the dislodged ADB counted. The trees used for monitoring were evenly disfributed among
the caged trees (Figure 1).
1991/92 SEASON
Exclusion caging
This trial was designed so that one group of flower clusters was exposed to ADB each week
between the 27.9.91 and the 15.11.91. To distinguish ADB damage from that caused by thrips
two types of cage were used. One was the quarantine mesh cage, as used in the 1990/91
season, the other, a cloth cage that excluded both ADB and thrips. Cloth cages consisted of a
cylindrical Waratah Insulmesh® frame covered by a white cotton sleeve with a draw string at
the neck to seal the cage around the branch. The cloth cages were 20 cm long and 15 cm in
diameter.
At spurburst (27.9.91) seven cages of each type were placed over flower clusters in each of 20
trees (Figure 2 ). Each cage enclosed three flower clusters which were shaken vigorously to
remove any ADB and thrips. This was done on each occasion a cage was installed. At the end
of the first week, cages for the fu-st exposure were put on and those for the second exposure
removed. This procedure was carried out each week for seven weeks, covering all the
exposure periods, treatments A - G. One set of cages (control) remained in place throughout
the trial period.
The flowers within the cages were hand pollinated on 19 - 20 October 1991 with flowers
from the Delicious cultivar, collected from a commercial orchard (The Pines) in Orange. All
cages were removed on 15.11.91 and the trees sprayed immediately with azinphos-methyl and
at 3-weekly intervals thereafter to eliminate ADB and prevent fiirther injury.
Page 54
Figure 2.
Exclusion trial trees and background population tap trees
+
o
0
+
o
6 0
o
o 13[o]
o
o
o
.
0
+
N
0
14|V]
i (+)
+
8
o
0
©
0
+ 60
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0
o
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0
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+
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o
+
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o
o
lafol
+
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--s
18 .
r
r-0
119 +
7©
r-0
I
ilO +
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•--a °
90
10
+
o
o lOfo"]
160
80
40
Graimy Smith
Jonathan
Missing tree
Cage tree
Tap tree
o
+
.
D
0
The treatments were:
->
A
exposed
27.9.91
B
exposed
4.10.91
->
C
exposed
11.10.91
->
D
exposed
18.10.91
-^
E
exposed
25.10.91
->
F
exposed
1.11.91
->
G
exposed
8.11.91
->
Control
unexposed
All c£iges were removed on the November 26.
Page 55
4.10.91
11.10.91
18.10.91
25.10.91
1.11.91
8.11.91
15.1191
Fruit damage assessments were conducted in late November and at harvest (mid-March) with
the fruit classified as in the 1990/91 season. The orchard's general ADB population was
monitored three times per week using the same technique as in the 1990/91 season. The ten
sample trees were distributed evenly among the caged trees (Figure 2 ). The phenology of
these trees was classified as in the previous season.
The thrips population was monitored in a neighbouring block (I - block) using rectangular
sticky traps.
Density caging
Twenty two insect proof cloth cages, constructed as described above, were fitted to each of 19
trees at bud separation (1.10.91). Four flower clusters were enclosed in each cage
(watershoots and long laterals were not used). Where insufficient caging sites (clusters) were
present on a single tree, two or more adjacent trees were grouped as a single treatment
(Figure 3 ). Each week ADBs were introduced into cages at three densities, (4, 8 and 16) on
each tree, one cage / density / tree. The ADBs were removed from the cages after one week
and the number of live and dead bugs recorded. The number of blossoms per cage was also
recorded when bugs were removed. Treatment details and tree phenology are given in Table
1.
Table 1.
Rep
A
B
C
D
E
F
G
Treatment details and phenology at the time of adding bugs to cages and
length of exposure.
Density
4
8
16
4
8
16
4
8
16
4
8
16
4
8
16
4
8
16
4
8
16
Date ADB added
Date ADB removed
Days exposed
2.10.91
9.10.91
7
Phenology in
H Block
(when bugs added)
BS
9.10.91
16.10.91
7
LP
16.10.91
23.10.91
7
F
23.10.91
30.10.91
7
PF
30.10.91
6.11.91
7
PF+7
6.11.91
13.11.91
7
PF+14
13.11.91
20.11.91
7
PF+21
Control
Page 56
ADBs were collected locally from wattles (Acacia spp.), tree lucerne (Chamaecytisus
proliferus) and Photinia sp. the day prior to treatments being applied. This was done by
branch tapping the host plant over a white plastic container and aspirating the ADBs into glass
vials (24mm x 50mm). The vials were capped and stored in a domestic refrigerator overnight
at4°C.
Pollination of caged flowers was carried out by hand, commencing at frill bloom (16.10.91 20.10.91) using flowers from the cultivars Jonathan and Bonza. Flowers were collected during
the afternoon prior to use and allowed to dehisce overnight.
The November and harvest assessments were carried as per previous seasons.
Figure 3.
Density trial trees and background population tap trees
o
+
+
o
o
+
o
0
o
o
o
100
o
o
©
+
o
o
o
o
o
o
+
6
o
o
o
70 o
o 50
+
o
+
90 80
o
10
o
o
16
14
o
0
0
0
20
13[o] o
n[o] n\V]
15
U
o
o
+
17
+
+
o
N
180
o
+
0 4 0
o
Granny Smith
Jonathan
Missing tree
Cage tree
Tap tree
o
+
Q
Q
Page 57
10
0
0
2
0
0
0
0
19
0
0
0
6 0
5H
1992/93 SEASON
Exclusion caging
The exclusion caging trial carried out during the 1991/92 season (as described previously) was
repeated in 1992/93, but with minor modification. First, the cages were deployed earlier in the
season, ie. at greentip (11.9.92) (Figure 4 ). Cages were removed from each treatment for 7
days and the clusters exposed to the ADB population. All cages were removed on 19.11.92
and the block sprayed with azinphos-methyl as in previous years. The exposure treatment
periods were:
A
B
C
D
E
F
G
exposed
exposed
exposed
exposed
exposed
exposed
exposed
25.9 -^ 2.10
2.10 -> 9.10
9.10 ^ 1 6 . 1 0
16.10-> 23.10
23.10^30.10
30.10^6.11
6.11 ->13.11
Spurburst (SB) -^ Early pink (EP)
Tight cluster (TC) -^ 2% Bloom (F)
2% Bloom (F) -> 30% Bloom (F)
30% Bloom (F) -^ 60% Petal fall (PF)
60% Petal fall (PF) -» Petal fall (PF)
Petal fall (PF) -^ Petal fall + 7 (PF+7)
Petal fall + 7 ^ Petal fall + 14 (PF+14)
Control - unexposed, clusters remained caged throughout the fhiit development, trial period.
Figure 4.
Exclusion trial trees.and.population tap trees (H
Block, Bathurst A.R.S) 1992-1993
EepcT]
0
+
E5Q E6[F]
E 5 0 E6[T]
0
o
+
+
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©
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o E7[o] E g g E15{T1
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o
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Granny Smith
Jonathan
Missing 1xee
Cage tree
Tap tree
0
+
•
u
0
Page 58
The other change from the previous season was that at the end of exposure periods C to G the
inflorescences were shaken and then sprayed with endosulfan (1.9 mL/L) to remove any ADB
and thrips. The flowers were hand pollinated on 20 October 1992.
Thrips numbers were monitored throughout the fixiit development period, ie. in buds, flowers
and on fiiiitlets, as development progressed. Ten randomly selected non-trial inflorescences
from trees fitted with exclusion cages were collected weekly. The blossoms were placed in
labelled bags and transported to the laboratory in a portable refrigerator. Thrips were extracted
from the samples using an Evans Apparatus (Figure 5). After allowing the samples to reach
room temperature, which activated the thrips, they were placed on the mesh platform in the
Evans apparatus. The turps-soaked lid was replaced quickly to prevent the escape of the thrips
and the black sleeve placed over the top of the cylinder to exclude light. A fluorescent light
was placed below the apparatus to attract the thrips. Repelled by the turps and attracted to
light the thrips moved through the mesh platform and collected on the grided paper below.
The grided paper was soaked in 70% alcohol to immobilise the thrips. After 20 minutes the
thrips were counted. The paper bags used for collection were checked for remaining thrips
which were then added to the count.
Figure 5.
"A simple method of collecting thrips and other insects from
blossom" J.W.Evans 1933
Q.
Cotton pad soaked
in turpentine
Black sleeve
Grided paper
soaked in alcohol
Mesh platform
'11
^
/
Light source
Page 59
Thrips and ADB numbers were also monitored using white sticky traps, which were placed in
the orchard block. These traps were commercially available disposable traps from Michigan,
USA. Ten sticky traps (20 cm x 16 cm) were deployed and checked three times per week for
ADB and thrips. A 10 cm x 2 cm rectangle of wire was placed in the centre of each side of the
trapping surface and the number of thrips counted. ADB were counted over both sides of the
sticky traps.
To support the caging experiment described above, the preference of ADB for flowers at
certain stages of development was also checked by sampling 50-100 clusters at known
phenologicai stages and extracting ADB using the Evans apparatus. This was carried out with
samples taken from three varieties, Delicious, Granny Smith, and Jonathan, from another
block (I Block) at Bathurst A.R.S.
Density caging
This season (92/93) the density caging experiment was carried out using a single density
treatment of eight ADB per cage. Cages were placed in the trees at greentip (11.9.92) with
four inflorescences in each. There were 14 treatment periods on each of 33 single tree
replicates (Figure 6 ). The previous standard treatment period of seven days was reduced to a
three or four day period during the main blossom period. Details of the treatment periods and
the corresponding stage of development are given in Table 2. ADB was collected as in the
previous season. After the exposure period the ADB were removed from the cage by branch
tapping and the number of bugs recovered recorded. To ensure that the ADB were eliminated
the flowers, fruit and foliage, as appropriate, were sprayed with tau-fluvalinate (Klartan®). The
number and phenology of the flowers or fiiiitlets in each cage was recorded when the ADB
were removed. Hand pollination of the caged flowers was carried out at 70% to fiili bloom
(10.10.92) and in cages where a majority of the flowers were not open, pollination was
repeated on 18-19.10.92. Cages were removed on 19.11.92 and the block sprayed with
azinphos-methyl. The November and harvest assessments for fruit damage took place during
the week commencing 30.11.92 and on the 16.3.93 respectively. The general orchard
population of ADB was monitored as in previous seasons.
Page 60
Figure 6.
Density trial trees and background population tap trees
0
0
+
0
0
+ 1E18[T|
0
0
0
0
0
o
0
0
-
0
o
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o
o
+
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^
0
6
+
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0
0
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tN
320
3 . 0 300
170 0
0
160
330
(o)
o
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290 2 3 0 2 2 0
280 2 4 0 9 0
140
+ 210
130
0 8 0
120 2 5 0 2 0 0
o
0
0
0
0
©
o
+
o
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+
0
0
0
0
0 270
5) ©
0
0
0
+
0
0
+
10
0
0
G)
o
o
Jonathan
Missing tree
Cage tree
Tap tree
+
+ 7 0
150 110 2 6 0 6 0
o
0 100 5 0
30 20
+ 40
©
Granny Smith
+
.
n
o
Page 61
190
0
Results
1990/91 SEASON
Exclusion caging
The results presented are based on the number of days the firuit were exposed to the ADB
between 25.9.90 and 1.11.90, and the level of fruit damage that had occurred by 12.11.90 and
at harvest (3.4.91). Details of the caging dates and exposvire periods are given in Table 3. The
results of the damage assessments carried out on the 12.11.90 and at harvest are presented in
Tables 4 and 5 respectively.
Orchard phenology as recorded in the 10 sample trees at the time of exposure is included in
Table 3. The general "in tree" ADB population, as measured by branch tapping increased
rapidly from full bloom (8.10.90) and peaked at 10.2 ADB per 50 blossom clusters, 10 days
after frill bloom (Table 3).
The assessments of fruit damage were difficult to interpret. The reasons for this were that the
exposure to ADB increased over the caging period and the resulting damage was cumulative
with exposure, and therefore could not be directly attributed to any particular period or stage
of fruit development. Plague thrips {Thrips imaginis Bagnall) (Thysanoptera: Thripidae) were
also a problem as they were not excluded from the flowering clusters by the quarantine mesh
cages and were found to cause extensive damage to the flowers stalks and the ovaries by
ovipositing in them. The damage to fruit caused by thrips resulted in small russet marks and
minor dimpling which was difficult to distinguish from minor ADB damage. Of those fruit
that remained in the cages throughout the season, that is with no exposure to ADB, 3.6% were
recorded as having ADB damage, indicating that either the cages were not 100% ADB proof
or that thrips can cause more severe dimpling than was expected.
The percentage of fiixit downgraded at harvest is given in Table 5. The results show that the
level of froiit damage caused by ADB and by thrips was higher at the November assessment
than at the harvest. This indicates preferential shedding of damaged fruit. At the November
assessment a total 2923 fiuit were examined compared with only 1291 at harvest in April,
indicating that 55.8% of the Suit used in the caging experiment was shed prior to harvest.
The percentage of fruit downgraded is greatest (<19.2%) in the treatments with the longest
exposure time (Figure 7).
1990/91 seasonal summary
The complex trial design made the results difficult to interpret. However, when the damage
atfributed to thrips is separated from the more severe types of damage attributed to ADB, the
results suggest that most damage caused by ADB occurred from early pink to just after frill
bloom. It would also appear that ADB damaged fiuit are shed preferentially and that thrips
damage to stalks may also cause shedding. However, because the cages did not exclude thrips
and it was difficult to distinguish between minor ADB and thrips damage, the exact amount of
damage caused by ADB could not be determined.
Page 62
Table 3.
and
Apple dimpling bug exclusion trial 1990/91 season: Phenology, exposure
mean apple dimpling bug population details for "A" and " B " trees.
Date cage moved
25.9.90
28.9.90
2.10.90
4.10.90
8.10.90
12.10.90
16.10.90
19.10.90
22.10.90
25.10.90
29.10.90
1.11.90
Table 4.
Total days
exposed
A
B
38
34
3
32
7
28
9
24
13
20
17
21
17
14
24
11
27
7
30
4
34
0
37
Phenology when first exposed
Mean number ADB
(per 50 clusters)
EP
P
LP
60%F
F
F+4
F+7
F+10
F+13
F+17
F+20
F+24
0.1
0.9
0.9
0.4
1.4
6.4
7.3
10.2
5.2
6.7
6.3
3.8
Fruit damage assessment November 1990.
A Trees
Days exposed
No. fruit
%ADB
% Thrips
%Damage'
38
34
32
28
24
20
17
14
11
7
4
0
126
165
138
116
168
133
99
134
129
135
128
107
23.8
20.6
18.1
15.5
13.1
9
5.1
9
3.9
6.7
14.8
8.4
17.5
19.4
19.6
14.7
22
27.1
28.3
33.6
20.9
23.7
25.8
15.9
41.3
40
37.7
30.2
35.1
36.1
33.3
42.5
24.8
30.4
40.6
24.3
Days exposed
No. fruit
%ADB
% Thrips
%Damage'
3
7
9
13
17
21
24
27
30
34
37
159
132
164
152
134
80
110
99
66
123
126
5.7
11.4
2.4
7.2
12.7
7.5
6.4
20.2
12.1n
22
16.7
19.5
22.7
28.1
25
20.9
22.5
17.3
27.3
21.2
26
31.7
25.2
34.1
30.5
32.2
33.6
30
23.6
47.5
33.3
48
48.4
B Trees
' Combined ADB and thrip damage
Page 63
Table 5.
Fruit damage assessments at harvest 1990/91 season.
A Trees
Days exposed
No fruit
%ADB
%Thrips
%Dainage
%Downgraded
38
34
32
28
24
20
17
14
11
7
4
0
78
85
82
70
89
79
58
78
79
80
64
55
26.9
17.6
14.6
11.4
6.7
8.9
6.9
T6.4
2.5
3.8
6.3
3.6
9
8.2
13
5.7
11.2
13.9
3.5
11.5
11.4
7.5
13.9
11.1
35.9
25.9
28.6
17.2
18
22.8
10.4
18
14
11.3
20
14.9
19.2
10.6
7.8
5.7
3.4
2.5
1.7
1.3
0
2.5
3.1
0
Days exposed
No fruit
%ADB
%Thrips
%Damage
%Downgraded
3
7
9
13
17
21
24
27
30
34
37
41
87
74
81
87
79
58
64
62
43
52
56
90
3.5
9.5
0
5.7
6.3
5.2
7.8
8.1
7
26.9
19.6
24.4
3.5
6.8
12.4
11.9
3.8
5.2
20.3
14.5
9.3
9.6
12.5
10
6.9
16.2
12.4
17.9
8.9
10.4
28.2
22.6
16.3
36.6
32.2
34.5
1.1
5.4
0
2.4
5.1
0
3.1
3.2
5.7
19.2
12.5
11.1
B Trees
3Q r
3a r
25
2S
2Q
i:
f.^
i 10
£
3 a 3 < i a 2 2 a 2 4 2 C l 1 7 1'l11 7
3
4 Q
Day •£ oKpasa ra
Figure 7.
7
9
13 17 21 2 4 27 3 0 34 37 41
Days ax pcvsu re
Percentage of fruit downgraded at harvest due to ADB damage
1990-1991.season
Page 64
1991/92 SEASON
Exclusion caging
ADB first appeared in the finit clusters at EP and the numbers increased steadily reaching a
peak at complete petal full, after which they gradually declined (Figure 8). The blossom
within the cages appeared to be more advanced (observation only) than in uncaged parts of the
trees. There was also a considerable amount of variation in blossom development among
treatment replicates. Orchard phenology, as recorded in the 10 sample trees at the time of
exposure is included in Table 6. Warm dry weather meant that the blossom period was very
short this season and the flowers senesced very quickly. As a consequence there was
insufficient time to hand pollinate all the cages before many of the flowers became
unreceptive and resulted in low finit set. At harvest there were only 504 fiuit available from
the treatments for assessment.
The results fi-om the two types of cages, cloth and quarantine, have been combined and the
results fi-om the November assessment are given in Table 6. Most damage fi"om ADB
occurred between early pink (EP) and one week after petal fall (PF+7) with the highest level
of damage occurring between EP and PF. When damage per bug is calculated, flowers are
seen to be most susceptible from bud separation (BS) tofiiUbloom (F).
Minor damage thought to be the result of thrips ovipositing in the flowers stalks and ovaries
was abundant (37.3 stings /100 fruit) on all fioiit in the quarantine mesh cages, including the
unexposed controls, irrespective of exposure time (Table 7). In the cloth cages thrips marks
were absent from the fi:aiit caged in the last exposure period and in the unexposed controls
(Table 7). Minor damage onfi-uitin cloth cages peaked when exposed from fiiU bloom (F) to
complete petal fall (PF), which corresponded to peak abundance of plague thrips (as
monitored in a neighbouring block of apples (Table 8).
Figure 8.
Mean ADB population in the trial site ( H Block, Bathurst A.R.S)
1991-1992
Petal tall
23.10
30.10
\Afeek ending
Page 65
20.11
Table 6.
Damage to Granny Smith apples, bugdays and relative susceptibility of different
growth stages after one week exposures to natural apple dimpling bug
population in the 1991-1992 season
Treatment
Q + C Bugdays/ Susceptibility No.fruit
Cloth
Phenology within
Quarantine
index^
2
50 clusters
cage at
cage (Q)^ cage (C)^
removal
replacement
A
BS
EP
3.0
0.0
1.5
6.6
23.0
117
B
EP
5%F
24.6
14.5
19.6
52.6
37.2
131
C
5%F
F
21.2
52.8
37.0
79.4
46.6
193
D
F
PF
11.6
41.7
26.7
164.8
16.2
79
E
PF
PF+7
8.9
12.5
10.7
210.6
5.1
85
F
PF + 7
PF + 14
3.0
0
1.5
95.1
1.6
70
G
PF + 14
PF + 21
0
0
0
31.1
0
69
0
0
0
0
Control
71
^ Number of stings per 100 fruit
^ Bugdays is a measure of bug activity taking account of bug numbers
and the time they are active
The susceptible index is damage
(Q+C)
2
per bugday X100
Table 7.Number of stings attributed to plague thrips per 100 Granny Smith apple after
week long exposures to the natural plague thrips population 1991-1992
Treatment
Phenology
Quarantine
No.fruit
cage
No.stings/100
Cloth
No.fruit
A
BS->EP
66
39.4
51
cage
No.stings/lOO
fruit
2.0
B
EP -> 5%F
69
64.8
62
32.3
C
5%F -» F
104
70.2
89
66.3
D
F->PF
43
67.4
36
100.0
E
PF-»
PF+7
PF + 7->
PF+14
PF +14-*
PF + 21
45
108.9
40
12.5
33
72.7
37
5.4
29
51.7
40
0
51
37.3
20
0
fruit
F
G
Control
Page 66
Table 8.
Thrips records in Granny Smith I Block, Bathurst A.R.S in the 1991-1992
season
Date
Phenology
Number of thrips'
4.10
P
214
11.10
10% F
610
18.10
60% PF
287
25.10
PF + 2
1301
1.11
PF + 9
263
8.11
PF+16
205
Total number of thrips in 6 traps, area 40cm^
The harvest assessment results are shown in Figure 9. In the thrips proof cloth cages fruit
damage caused by ADB and the resulting downgrading of fruit is highest between full bloom
(F) and petal fall (PF), although some downgrading resulted from damage incurred between
bud separation (BS) and late pink (LP). In the quarantine cages ADB damage occurred from
bud separation (BS) to frill bloom (F), although some damage also occurred during the last
exposure period (G). No assessment for damage by thrips was carried out at harvest.
To establish the period when fruit are most vulnerable to damage by ADB an index of
susceptibility was calculated. This was done by dividing the percentage of fruit damaged (in
both types of cage) by the mean number of ADB counted by limb tapping during the exposure
period and multiplying by 100. The relationship between the susceptibility index and the
exposure time is presented in Table 9. Relatively low numbers of fruit were available for
assessment due to poor pollination, however, from the susceptibility index calculations, bud
separation (BS) to petal fall (PF) is the period of greatest risk from ADB attack.
Figure 9.
Percentage of fruit downgraded due to ADB damage in cloth and
quarantine cages during the 1991-1992 season
30
25
S20
• Quarantine
[]] Cloth
&15h
D
E
Treatment
Control
Page 67
Table 9.
Combined harvest assessment data, cloth and quarantine cage 1991-1992.
Treatment
No.fruit
Bugdays/50 clusters
% downgraded
Susceptibility index
2
A
B
C
D
E
F
G
Control
0.53
0.14
0.18
0.07
0
0
0.06
0
6.6
52.6
79.4
164.8
210.6
95.1
31.1
0
3.5
7.6
14.1
12.2
0
0
2.0
0
57
92
142
41
48
34
50
40
' Bugdays is a measure of ADB activity taking account of numbers and the time they are active
^ Susceptibility index is % downgrading/ bugday
Density caging
The number of flowers in each cage was low (Table 10). Initially each cage contained 24
flowers, however hand pollination was not very successful and the unpollinated flowers failed
to develop. As mentioned previously, the reason for this was the due to a short receptive
period of the blossom, the rapid senescence of flowers and possibly poor pollination material.
Mean flower or fruit numbers were approximately 19 per cage for the period BS - F, but
declined sharply to 2.3 per cage over the next four weeks (Table 10). Removing ADB from
the cages at the end of each treatment period was very difficult and on average only 59% were
recovered. Of these 70% were alive. The number of ADBs recovered from cages is given in
Table 11. Many of the ADBs remained in the foliage and flowers despite vigorous attempts to
shake them out. From treatment period C onwards the fruit and foliage were sprayed with
"Black Flag" (active ingredients tetramethrin 4.8g / kg, piperonyl butoxide 13.2g / kg and
phenothrin 0.22g / kg) to kill those ADB that remained.
Table 10.
Total and mean number of flowers per cage in each time and density
treatment.
Treatment
A
B
C
D
E
F
G
Control
Mean number of flowers/cage
Number of flowers/cage
4
348
365
381
152
195
103
47
8
384
403
361
176
89
88
43
405
16
364
346
326
168
108
68
44
Page 68
4
18.3
19.2
20.1
8.0
10.3
5.4
2.5
8
20.2
21.2
19.0
9.3
4.7
4.6
2.3
21.3
16
19.2
18.2
17.2
8.8
5.7
3.6
2.3
Table 11.
Bug recovery details, Density Trial 1991-1992.
Treatment
Density
A
4
8
16
4
8
16
4
8
16
4
8
16
4
8
16
4
8
16
4
8
16
B
C
D
E
F
G
Total
recovered
50
102
166
31
68
168
36
85
176
45
92
189
40
91
189
46
92
214
35
99
165
% bugs
recovered
69.4
70.8
57.6
40.8
44.7
55.3
47.4
55.9
61.1
59.2
60.5
62.4
52.6
59.9
62.2
60.5
60.5
70.4
46.1
65.1
54.3
% dead
% alive
40.0
37.3
43.4
25.8
39.7
20.8
44.4
42.4
45.5
37.5
30.4
32.8
32.5
36.3
27.0
39.1
25.0
20.6
28.2
9.1
20.0
60.0
62.7
56.6
74.2
60.3
79.2
55.6
57.6
54.5
62.5
69.6
77.2
67.5
63.7
73.0
60.9
75.0
79.4
71.4
90.9
80.0
The results o: ' the November assessment are svimmarised in Tables 12, 13 and 14. Ta
presents the number of ADB stings per fruit for each treatment at each density of ADB. The
number of fruit available for attack declined over time and hence the relative density of ADB
per fruit also changed, increasing as the season progressed. A index of susceptibility to ADB
damage was calculated by multiplying the mean number of ADB stings per fruit (Table 12)
by the corresponding number of blossoms or fiaiitlets available for attack (Table 13). The
index of susceptibility is presented in Table 14. The susceptibility index shows that fruit is
most susceptible during the treatments periods A to D (2.9.91-30.10.91), ie. from bud
separation to petal fall.
Table 12.
i
Time-^
Density
4
8
16
Mean number of ADB stings per fruit, November assessment
A
B
0.6
0.7
0.6
C
1.7
1.2
2.2
D
1.0
0.6
2.9
E
0.3
0.3
1.3
Page 69
G
F
0
0.2
0.1
0
0.05
0
Control
0.02
0
0.09
0.03
Table 13.
Summary of the number of blossoms, fruitlets available for attack by
ADB.
Time->
Density
A
B
C
D
E
F
G
4
8
16
18.3
20.2
19.2
19.2
21.2
18.2
20.1
19.0
18.1
10.3
9.5
9.8
6.1
4.7
5.7
5.4
4.6
3.5
3.2
2.1
2.4
i
Table 14.
Index of susceptibility. Bold numbers reflect index of susceptibility scaled
to a maximum off 1 at the most susceptible time for each time/density
period.
Time->
Density
A
B
C
D
E
F
G
4
11.0
0.39
14.1
0.61
11.5
0.20
32.6
1.00
25.4
1.00
40.0
0.69
20.1
0.62
11.4
0.52
52.5
1.00
3.1
0.19
1.4
0.25
12.7
0.42
0
0
0.9
0.17
0.6
0.03
0
0
0.2
0.08
0
0
0.1
0.01
0
0
0.2
0.03
i
8
16
The results of the harvest assessment show that almost all the ADB damage occurred in cages
that were occupied by ADB until full bloom (Table 15). The results show that by the time the
flowers were at full bloom damage levels had reached 72.7% in cages with 16 ADB
compared with 18.2% in cages with 4 ADBs which shows that fruit damage increases with
population density (Table 15).
Table 15.
Percent fruit downgraded at harvest
Time^
Density
A
B
C
D
E
F
G
4
8
16
16.7
13.7
28.6
35.2
20.8
55.6
18.2
25.0
72.7
5.3
0
0
0
0
0
0
0
0
0
0
0
Page 70
A cumulative measure of ADB activity (referred to as Bugdays) over the period fruit are
susceptible has been developed. As a measure, Bugdays avoids the bias that results from
variation in the length of the bloom and fruit development period between seasons. Bugdays
has been defined by Bower et al (1992) as:
t
Bugdays =
S (x^±X2^)-(d„+i-d„)
n+1 2
where x = number of bugs in sample
d = number of days after first sample
n = sample number
t = number of last sample
The estimated number of Bugdays for each treatment period during the 1991/92 season are
presented in Table 16 and a susceptibility index at harvest based on the percentage of fruit
downgraded divided by Bugdays in Table 17 and Figure 10. This index shows that most of
the damage that resulted in downgrading of fruit occurred during treatments A-C, ie bud
separation to fiiU bloom.
Table 16.
Estimates of Bugdays (all bugs in for 7 days)
Time-^
Density
A
B
C
D
E
F
G
24.2
48.6
98.0
26.5
51.0
105.6
25.1
49.4
96.4
24.3
50.9
104.0
25.6
49.9
102.6
24.7
51.8
104.3
26.2
54.3
105.9
i
4
8
16
Table 17.
Susceptibility index (% fruit downgraded per bugday)
Time->
Density
A
B
C
D
E
F
G
0.8
0.39
0.28
0.51
0.29
0.24
1.33
1.00
0.41
1.00
0.53
0.77
0.72
0.41
0.51
0.73
0.75
1.00
0.22
0.06
0
0
0
0
0
0
0
0
0
0
0
i
4
8
16
Boldfiguresare scaled to a maximum of 1 at most susceptible period.
Page 71
Figure 10.
Susceptibility index during different exposure periods (A-G) in the
1991-1992 season
4 BUGS
C
D
E
Time period
The results of the orchards 'in tree' ADB population, measured, as in previous seasons, by
branch tapping is shown in Figure 8. The results show that ADB population was present in
the blossoms over an eight week period. The population increased rapidly through until fiiU
bloom and then declined just as rapidly during the four weeks after at petal fall.
1991/92 seasonal summary
Thrips damage was found in all the quarantine mesh cages, including those that were in place
for the entire treatment period, confirming that thrips were able to penetrate these cages. In the
cloth cages there was no thrips damage in the controls that also remained in place throughout
the trial period or in the cages that were removed for the last exposure period (G) (Table 13).
This shows that thrips could not penetrate the cloth cages. The differences between the two
cage types enabled the level of damage by ADB to be determined. Most of the damage
attributed to thrips occurred in the period early pink (EP) to petal fall (PF), which
corresponded to the peak abimdance of plague thrips (Table 14).
Most ADB damage occurred between early pink (EP) and one week after petal fall (PF)
(Table 12). When the damage per ADB is calculated, flowers are most susceptible from bud
separation to fiill bloom (F) and that susceptibility declines after full bloom (Table 15). These
findings in November are supported by the harvest assessments. The results from the density
caging experiment show that damage occurs between bud separation and complete petal fall,
however, most of the damage occurred in the two week period from late pink to complete
petal fall. Very little damage occurred in the four weeks after petal fall. This pattern was true
for the absolute damage figures (Table 15) and for those adjusted to account for varying
densities of ADB (Table 14). The results show that the greater the ADB population the
greater the potential for fruit damage. ADB survival in cages remained high for up to four
weeks after petal fall (Table 11). This suggests that after petal fall ADB were either, feeding
on fruit which did not result in damage or were feeding on parts of the tree other than fixiit,
possibly the soft, rapidly growing leaf buds.
Page 72
1992/93 SEASON
Exclusion caging
The mean numbers of ADB and thrips caught on white sticky traps in the cage trial site (Hblock) are presented in Figure 11. During the spring thrips numbers remained relatively low
and previous work (W.G. Thwaite pers. comm.) indicates that higher numbers of thrips are
needed to cause serious damage. The number of thrips extracted from inflorescences collected
in H block using the Evans apparatus is shown in Figure 12. These two measures of the thrips
population indicate that 1992/93 was a low pressure season for thrips.
Figure 11.
site
Mean numbers of ADB and thrips found on white sticky traps in the trial
(H Block) in the 1992-1993 season
2.ia
le.iQ
30.10
Week end ing
The results of the November and harvest assessments of fruit damage are shown in Table 18.
The majority of damage to fixiit occurred in the exposure period 2% bloom to 60% petal fall
(Treatments C and D). As in the previous season, poor pollination is thought to have been
responsible for the low number of fruit set. At the November assessment 1347 fruit were
examined compared with 965 at harvest. In both types of cage, higher levels of damage were
recorded at the November assessment than at harvest. This supports the finding that fruit
damaged by ADB is shed preferentially. This trend is shown in Figure 13. Thrips were not
considered a major contributor to the minor ADB damage (Class 1) because the differences in
the level of damage in thrips proof cloth cages and non-thrips proof quarantine cages were not
significant (Table 19).
2.10
9.10
16.10
23.10
30.10
6.11
Vêkendng
Figure 12.
Mean number of thrips found per inflorescence (n=10) collected weekly
from 10 trees ( H Bloc, Bathurst A.R.S) during the 1992-1993 season
Page 73
Table 18.
Difference in damage percentages between quarantine cages and cloth cages in
November and at harvest.
Figure 13.
HARVEST
CLOTH
QUARANTINE
0
0
5
7.1
NOVEMBER
QUARANTINE
CLOTH
3.8
1.6
TREATMENT
A
B
C
D
E
F
G
CONTROL
13.8
31.5
24.2
15.3
14.3
47.8
15.9
5.4
5
0
0
0
0
0.6
0
0
4.3
5.4
1.3
0
8.6
2.6
8.4
34.1
20.2
20.4
Percentage damage (ADB, thrips or both) at the November assessment
and at harvest in cloth and quarantine cages in the 1992-1993 season
Ha-vest
• Quarantine
• Ooth
D
E
F
G
H
CantH
G ContiQl
The ADB's preference for flowers at certain stages of development are shown in Table 20.
Table 19.
ADB 1st class damage at harvest in 2 cage types.
TREATMENT
A
B
C
D
E
F
G
CONTROL
QUARANTINE C A G E
CLOTH CAGE
0
0
3.5%
10.3%
4.2%
4.1%
10.4%
4.7%
0
0
0
0
0
1.3%
0
0
Page 74
Table 20.
Number of ADB extracted from 50 clusters (using Evan's apparatus) at various
phenological stages in three apple varieties.
Variety
Granny Smith
Delicious
Jonathan
Phenology
Late pink
Full bloom
Petal fall
Full bloom
Petal fall
Late pink
Full bloom
Petal fall
Number ADB/50 clusters
1.8
17.5
5.5
6.0
6.5
0
10.5
2.5
Density caging
The phenology of caged fruiting clusters was recorded when the ADB were removed and is
presented in Table 21. Over the season 75.7% of the ADB were refrieved from the cages, of
these 41% were dead (Table 22). Tau-fluvalinate was used to kill any ADB remaining in the
clusters or fruitlets before recaging.
The most severe damage, ie the highest number of fruit classified as juice, occurred in
treatment H which was the period between frill bloom and petal fall. The number and
classification of damaged fiiiit at harvest is shown in Table 23. The level of fruit dovmgraded,
ie. class 2 and juice fiuit, at harvest reached 31.9% (Figure 14). More fruit was recorded as
damaged at the November assessment than at harvest indicating that fruitlets damaged by
ADB are shed preferentially. At the November assessment the largest amount of damaged
fruit was recorded in treatments H which corresponds with the results at harvest (Table 24).
The general orchard population of ADB, which was monitored by branch tapping on the days
that cages were removed, is recorded in Table 25. There was a phenological difference
between the blossom and fruit clusters in the cages and those on the trees used to monitor the
general orchard population of ADB. Fruiting clusters within cages reached frill bloom early,
ie. between 6 and 16 October (Table 20), whereas those on the sample trees did not reach frill
bloom until 20 October (Table 25). When the presence of orchard's general ADB population
is compared with the percentage of fruit damaged by ADB in cages, the two measures overlap
only during the blossom period. This supports the finding that very little, if any damage is
caused after the blossom period despite the presence of ADB in the frees through the rest of
the season (Figure 15).
Page 75
Table 21.
Cluster / fruitlet phenology counts in treatments recorded when ADB were
removed from cages 1992-1993
Date
22.09 25.09 30.09 2.10 6.10 9.10 13.10 16.10 20.10 23.10 27.10 30.10 3.11 6.11
(bugs removed)
A
K
L
M
N
Treatment
B
C
D
H
1
E
F
G
J
Greentip
23
8
Spurburst
4
49
2
Tight cluster
48
15
6
Bud separation
19
49 33
Early pink
52 45 20
6
9
Pink
12 30 35 11
1
Late pink
14 47 44
1
13
Bloom
16
26 68
61
Petal fall
54
59
16
Petal fall+3
50
16
59
Petal fall+7
50
40
56
Petal fall+10
40 137
Petal fall+>10
X
121 X
X
Petal fall + 3 = 3 days after petal fall
The mode phenology(bold) was used to indicate the phenology of each treatment,
when bugs were removed from the cages
Figure 14.
Percentage of fruit downgraded at harvest and phenology of blossom
clusters when ADB were removed from cages
Phenc3)ogy wfien bugs nemouad
GT
SB
TC
BS
EP
P
LP
F
PF
PF+
°
PF+18
PF+21
r:'",
Page 76
Greentp
Spirburst
Tight duster
Bud separation
^rtypink
Pink
Late pink
Full bloom
Petal^ll
[bâterpdalM
1
N
I
Certrcl
Table 22.
Details of ADB recovered from cages in density trial, H block 1992.
Treatment
A D B in
A D B out
A D B out
A D B out
% ADB
retrieved
(live)
(dead)
(total)
A
B
C
D
E
F
G
H
I
J
K
L
M
N
216
264
264
264
264
264
264
264
264
264
264
264
264
264
0
78
54
103
108
76
135
144
87
176
177
141
173
152
153
141
135
105
116
107
58
33
81
33
40
70
41
44
153
219
189
208
224
183
193
177
168
209
217
211
214
196
70.8
83.0
71.6
78.8
84.8
69.3
73.1
67.0
63.6
79.2
82.2
79.9
81.1
74.2
Total
3648
1604
1157
2761
75.7
1992/93 season summary
Despite the presence of ADB throughout the season most damage to finit by this pest occurred
between 2% bloom and 60% petal fall with ADB showing a preference for flowers at full
bloom. The low numbers of thrips present this season meant that the definition of thrips and
ADB damage remains inconclusive.
The results of the density trial support the findings that most of the fruit damage and resulting
downgrading of fhiit caused by ADB occurred from full bloom to petal fall even though ADB
was present in the orchard throughout the frial period.
Figure 15.
Mean ADB population in the trial site (H Block) and percentage of
damage caused by ADB introduced into the cages in 1992-1993
IT
&
I.
E
I Dan^ge
E
•••llllll'aa
:a.u
a.'u
OMoan ADB number
'3JI
si'u ' * ' u z i ' u 3u.'u
Page 77
-jail z'g a.'u 'd.'u aa.'u »i.'u
Dîlcitbugs s i d e d tc» c ^ c s )
Table 23. The number and classification of fruit recorded at harvest as damaged by
ADB
Treatment
A
B
C
D
E
F
G
H
I
J
K
L
M
N
Control
Table 24.
Total number of
fruit
41
75
64
68
73
70
51
54
78
83
77
75
94
61
60
Number of
clean fruit
41
73
61
66
67
62
48
37
75
79
76
75
94
61
60
Number of fruit
ADBl
0
1
0
2
4
3
1
1
1
1
0
0
0
0
0
Number of fruit
ADB2
0
1
2
0
2
0
1
3
1
2
1
0
0
0
0
Nimiber of fruit
juice
0
0
1
0
0
5
1
13
1
1
0
0
0
0
0
Number and percentage of fruit recorded on 30 November and at harvest
(March 1993) as damaged by ADB.
Treatment
Number of
fruit
A
B
C
D
E
F
G
H
I
J
K
L
M
N
Control
53
88
76
77
79
75
60
63
87
91
94
84
104
71
62
November
Number of
fruit with
ADB
1
3
10
3
8
9
9
22
15
15
5
4
1
0
0
% fruit
damaged by
ADB
1.9
3.4
13.2
3.9
10.1
12
15
34.9
17.2
16.5
5.4
4.8
1
0
0
Page 78
Number of
fruit
41
75
64
68
73
70
51
54
78
83
77
75
94
61
60
Harvest
Number of
fruit with
ADB
0
2
3
2
6
8
3
17
3
4
1
0
0
0
0
% fruit
damaged by
ADB
0
2.7
4.7
2.9
8.2
11.4
5.9
31.5
3.8
4.8
1.3
0
0
0
0
Table 25.
Mean ADB numbers and phenology often sample trees.
Date
(Bugs removed from
cages)
22.09
25.09
30.00
02.10
06.10
09.10
13.10
16.10
20.10
23.10
27.10
30.10
03.11
06.11
Treatment
Mean ADB (background)
n=10
A
B
C
D
E
F
G
H
I
J
K
L
M
N
0
0
0
0.3
0.1
2.2
8.1
16.2
10.7
26.6
15.7
21.4
15.9
22.8
Phenology
(backgroimd)
visual assessment
GT
GT
SB
TC
EP
P
2%F
20% F
30% F
F
PF
PF + 4
PF + 7
PF + 11
Conclusion
This study has shown that the flowering and the initial fiiiit development stages of apple are
vulnerable to damage from ADB from bud-separation through until one week after complete
petal fall, with most of the damage occurring in the two weeks between early pink and
complete petal fall. Closer examination of the data shows that the most critical time for
damage is the period from 2% bloom until 60% petal fall. The ADB showed a definite
preference for flowers at fall bloom. Very little damage occurred in the four week period after
petal fall. The critical period for protecting fioiit can therefore be narrowed down to a roughly
three week period from pink to one week after petal fall. The trial showed that fiiiit damaged
severely by ADB is shed preferentially, resulting in a reduction in yield.
In the density trial, where ADB were caged at different densities, most of the fiiait damaged
and which resulted in a downgrading occurred from fiiU bloom to petal fall. This suggests that
most of finit damage between bud separation and fiiU bloom may result in only mmor
blemishes and hence may not be significantly downgraded. ADB survival m cages remained
high for up to four weeks after petal fall and, since there was no other source of food, this
suggests that after petal fall either their feeding on Iruit did not result in damage, or that they
were feeding on parts of the tree other than the fruit, possibly the soft, rapidly growing leaf
buds. The results show that the number of ADB present is correlated with the amount of finit
damage, the more ADB the more damage that is incurred, as would be expected.
Plague thrips (Thrips imaginis) were found to cause damage to developing fiiiit that was
difficult to distinguish from the minor damage caused by ADB. Most of the damage caused by
thrips occurred from early pink to petal fall, which corresponded with the populations peak
abundance. Thrips also damage the apple's stalk and fixiit damaged in this way may be shed
preferentially and add to the loss of yield.
Page 79
TECHNICAL REPORT 6
IDENTIFICATION OF DAMAGE TO FRUIT BY APPLE DIMPLING BUG
iCampylomma liebknechti (GIRAULT)) (HEMIPTERA: MIRIDAE)).
C.C. BOWER* AND A. HATELY'
1. NSW Agriculture, Kite St. Orange, NSW 2800.
2. Orange Agricultviral Institute, Forest Rd. Orange, NSW 2800.
Introduction
Apple dimpling bug feeds on the ovaries of flowers in October causing dimple-like
deformities in the apples as they grow. A range of lesser symptoms, such as russet marks and
minor holes, also appear. Apple dimpling bug is also likely to cause deformities to the internal
structure of the fhiit. The presence and nature of such internal damage may enable positive
diagnosis of external symptoms. There have been no previous studies of the internal
symptoms of damage caused by fruit feeding bugs.
Aim
The aim of this investigation was to document the types of external and internal scarring and
malformation caused by apple dimpling bug on the Red Delicious, Granny Smith and
Jonathan apple varieties.
Fruit was harvested from the Varietal Susceptibility Trials in 1990/91, 1991/92 and 1992/93
seasons at NSW Agriculture's Bathurst Agricultural Research Station, located on the Central
Tablelands of NSW. Fruit from this trial was examined for damage, both external and internal.
The trial site (I-block) consisted of 3 rows each of Red Delicious, Grarmy Smith and Jonathan
varieties (Figure 1).
Widely separated from the vmsprayed monitoring trees were 2 trees in each row that were
sprayed once or twice during the blossom period with fluvalinate or endosulfan to eliminate
ADB. All the other trees remained unsprayed . Damage seen at harvest in unsprayed trees is
the result of ADB or other insects feeding or ovipositing on the frees during the blossom
period.
The degree of internal damage to individual fruit was assessed by cutting the fruit in half in
the vertical plane and taking internal measurements of fruit deformation, including dimple
depth, core movement and vascular tissue (vein) movement. The measurements taken are
shown in Figure 2.
Page 80
The site of ADB damage on finit was classified as upper quarter, above equator, below
equator and lower quarter (Figure 3).
Figure 1
Layout of varietal susceptibility trial,
block 3 of I Block Bathurst A.R.S 1990
X
X
X X A X X X
X X A X X
X
X
X X A X X X
X
X
•
X X
X X A X X
•
•
•
X X
X X A X X X
X X A X X
•
•
X X
+ +
+ +
+
+
A + +
•
•
+ +
+ +
+
+ A +
+
+
+
+
A + +
•
•
+ +
+ +
+
+ A +
+
+
+
+
A + +
•
•
+ +
•
•
+ + +
0
o
A. o o
o
o
A o o
o
o
o o
o
o A o
o
o
0
o
A o
o o
o
o
o
o
o
o
o o
o
o A o o
o
o
o
Figure 2.
o
0
Variety
Treatments
X
+
o
Tap.tree
Trap.tree
Sprayed.tree
Delicious
Jonathon
Granny. Smith
Measuring internal dimensions of apple dimpling bug damage.
1. Distance to normal surface
2. Distance to base of dimple
3. Extended vein distance
4. Normal vein distance
5. Extended core distance
6. Normal core distance
Dimple depth =1-2 mm
Vein movement
=3-4 mm
Core movement
= 5-6 mm
Page 81
1990/91
Lov«r quarter
Figure 3
Belowequator
Above equator
Upper quarter
Distribution of apple dimpling bug damage on the fruit surface
1991/92
Lower quarter
Belowequator
Above equator
Upper quarter
Page 82
From 1990-1993 observations and measurements of internal damage were also made on
Granny Smith fruit harvested from the fruit susceptibility trials (the exclusion and density
trials) conducted in H-block, Bathurst A.R.S. as part of the present study (see Technical
Report 5). Delicious fruit harvested from a commercial orchard at Batlow was also assessed.
In 1991/92 Delicious fruit from I Block were also examined for internal damage.
1990-91
Klartan ® was applied to trees (as per Figure 1) on 18.10.90.
Delicious (total fruit = 7602), Jonathan (total fruit = 5939) and Granny Smith (total fruit =
7474) cultivars were harvested and examined for damage. The fruit was classified according
to the position of ADB scarring (Figure 3), damage type (Plate 1-4) and some finit was
dissected to determine internal damage (Figure 2).
Fiftyfour Delicious fruit from a commercial orchard at Batlow were also examined.
1991-92
Klartan ® was applied to frees on 11.10.91 (as per Figure 1). At harvest 4813 Jonathan fiiiit
were classified as ADB no.l or ADB no.2 type damage (according to guidelines in Technical
Report 5). 4537 Graimy Smith fruit were also classified as for Jonathans. Delicious fruit from
both sprayed and unsprayed trees were classified as for other cultivars . The Delicious finit
were also classified for site of ADB damage (Figure 3) and dissected to determine internal
damage.
Granny Smith fiaiit from the caging experiments (fioiit susceptibility trials) was dissected and
internal measurements made.
1992-93
Endosulfan was applied at late pink( 9.10.92) and petal fall (23.10.92) (as per Figure 1).
Delicious (7482 fi^lit), Jonathan (6549 fruit) and Granny Smith (6037 fiuit) examined at
harvest, were classified as ADB no.l or ADB no.2 and also the type of dimple identified
(Plate 1-4).
Granny Smith fruit from the caging experiments (fioiit susceptibility frials) was dissected and
internal measurements made.
Results
Damage that was confined to unsprayed trees, ie. did not occur on trees freated with
fluvalinate or endosulfan to eliminate ADB, was attributed to ADB, or other visitors to the
flowers or both. Four classes of external damage to fruit, including the classic ADB dimples,
were recognised as being caused by ADB at flowering. Details of both external and internal
deformities accredited to each category are:
a.
Classic ADB damage - (Plate 1 i, ii) a depression of varying shape with
russet scar in the base. Depression can vary in depth from less than 1mm to more than
10mm.
b.
Non-scar dimple - (Plate 2 i, ii) depressions without scars, that in the past
were not regarded as caused by ADB because it was thought that ADB must break the
fruit's skin to leave a scar. Various other problems can give rise to depressions, eg.
Page 83
lack of pollination and boron deficiency, however after examining the internal
damage, it was noticed that the developing apple may grow around the scar tissue
thereby internalising it.
Pinhole - (Plate 3 i, ii) a very narrow, deep conical depression going into the
apple, sometimes reaching the core and often without a dimple or superficial scar
tissue. This type of damage is common in Harold Red Delicious. The skin looks like it
has been poked with a pin.
d.
Volcano - (Plate 4 i, ii) so-called because it often consists of a crater-like
depression with a raised pimple-like cone in the centre. This cone is usually dark red
and quiet small. In some cases the cone is just on the skin without a dimple. This type
of damage is commonly found in Harold Red Delicious. Volcano type damage found
in dimples showed internal ADB damage whereas those found on the skin without a
dimple showed none of the characteristic internal ADB damage. The dark marks alone
(no dimple) are probably due to lenticel breakdown.
The amount of damaged fruit attributed to ADB during the 1990/91 season and the percentage
of each type found on sprayed and unsprayed trees of each cultivar is given in Table 1. The
amount of damaged Iruit attributed to ADB during the 1991/92 season is given in Table 2. In
this season there was 26.3% classic dimples, 52.1% non-scar dimples and 21.6% pinhole
dimples in the unsprayed delicious variety.The amount of damaged iruit attributed to ADB
during the 1992/93 season is given in Table 3. In this season there was 9.8% classic dimples,
74.7% non-scar dimples and 25.9% pinhole dimples in the unsprayed delicious variety. The
results show that Jonathan is less susceptible to damage by ADB than the cultivars Granny
Smith and Red Delicious.
Most of the damage occurred on the calyx half of the fiiiit (79% in Red Delicious and 65% in
Granny Smith) (Figure 3).
Table 1.
Percentage of fruit damage attributed to apple dimpling bug
according to damage type. I Block, Bathurst 1990/91
Treatment
No.fiiiit
3084
% ADB
damage
1.1
% classic
dimple
0.5
% non-scar
dimple
0.03
% pinhole
dimple
0.5
% volcano
damage
0.03
Sprayed
DeUcious
Unsprayed
Delicious
Sprayed
Jonathan
Unsprayed
Jonathan
Sprayed
Granny Smith
Unsprayed
Granny Smith
4518
11.7
1.2
1.5
7.2
1.8
2627
0.1
0.1
0
0
0
3312
1.1
1.0
0.06
0.03
0
2859
2.6
2.5
0.03
0.03
0
4615
11.7
11.5
0
0.07
0.1
Page 84
Plate l(i)
Classic ADB Damage
External
Plate 2(i)
Non-scar dimple
External
Plate 3(i)
Pinhole dimple
External
Plate l(ii
Classic ADB Damage
Internal
Plate 2(ii)
Non-Scar dimple
Internal
Plate 3(ii)
Pinhole dimple
Internal
Plate 4(i)
Volcano
External
Plate 5
Deformation of seed chambers
Plate 7
Distortion of vascular tissue
Plate 4 (ii)
Volcano
Internal
Plate 6
Distortion of core boundaries
Table 4.
Mean measurements of internal disfiguration in Delicious apples
caused by apple dimpling bug 1991/92 (mean ± s.e)
Type of damage
% of total
damage
Mean dimple
depth (mm)
Mean vein
movement (nrni)
26.3
Number of
deformities
measured
35
1.61 ±0.27
4.92 ± 0.56
Mean core
movement
(mm)
3.80 ± 0.44
Classic ADB
dimple
Non-scar dimple
52.1
70
2.03 ±0.16
2.59 ± 0.37
2.10 ± 0.31
Pinhole dimple
21.6
27
2.49 ±0.28
1.47 ± 0.53
0.80 ± 0.40
The assessment of internal damage to Delicious fruit foimd that shallow dimples (Classic
ADB) were associated with greater internal distortion of the fruits vascular bundle, ie. higher
measures of vein and core movement (Table 4). The evidence suggests that ADB feed
primarily on the juices carried by the vascular tissue to the developing flower.
Table 5 shows that mean dimple depth in Granny Smith fruit remained constant over the three
years. The results for Granny Smith are more uniform than those for Delicious fruit (Table 4)
because most ADB damage in Granny Smith is Classic ADB (Table 1) whereas in Delicious
the most common types of ADB damage are Non-scar and Pinhole.
Table 5.
Mean measurements of internal disfiguration in Granny Smith
apples caused by apple dimpling bug (mean + s.e)
Trial
Density trial 91/92
Exclusion trial 91/92
Density trial 92/93
Exclusion trial 92/93
Number of
deformities
measured
69
77
79
97
Vein movement
6.8 + 0.4"
8.9 + 0.5
5.2 ± 0.3
5.2+ 0.3
Core movement
(mm)
4.0 ±
5.4 +
2.8 ±
3.3 +
0.3
0.4
0.3
0.3
Dimple
depth
(mm)
2.9 ± 0.3
2.0 + 0.1
2.3 ± 0.2
2.3 +0.2
The internal effects of ADB feeding include deformation of the seed chambers (carpals)
(Plate 5), distortion of the core boundaries (Plate 6) and gross displacement of the vascular
tissues (veins)(Plate 7).
Page 86
Discussion
Damage was confirmed as caused by ADB if when dissected there was evidence of core or
vascular bundle distortion connected to the base of the dimple. These extensions (distortions)
were found to be localised to the area of ADB damage such that a narrow cone of tissue is
pulled out of the vascular bundle and is markedly distorted outwards fi-om its course, towards
the site of external ADB damage, ie. the dimple (Plate 7). Even the most superficial of
dimples cause pulling out of the vascular bundle and core segments. In most cases connectives
in the tissues join the scar of the dimple to the vascular bundle. The dimples appear to result
from tissue damage which interferes with the growth patterns of the fruit. Data collected
during the dissections indicates that ADB feed mainly on the vascular tissue of the ovary.
Occasionally dimple-like scars show no signs of internal changes and hence may not be
caused by apple dimpling bug.
Conclusion
Dissection of the damaged fruit revealed for the first time the patterns of internal damage
caused by ADB. Correlations of the internal damage with superficial symptoms enabled the
range of damage caused by ADB to be accurately determined. The range of internal and
extemal damage types has been described and photographed. The morphological evidence
suggests strongly that ADB feed on the juices conducted by the vascular tissue in the ovary of
the flower.
Page 87
CONCLUSION
Apple dimpling bug (ADB) is truly phytophagous, being found on 62 species of plants across
four states of Australia. ADB survive and breed throughout the year on whatever species are
in flower, their abundance increasing in spring when temperature and moisture are favourable.
In a particular year and at a particular site all apple varieties are equally atfractive to ADB.
Jonathan apples have an inherent resistance to ADB attack. Much less damage results on the
Jonathan cultivar despite high numbers of ADB being present throughout the blossom period.
Chlorpyrifos and Fluvalinate gave the best control of ADB in chemical trials. Chlorpyrifos is
a suitable choice for prophylactic applications at the pink bud stage of development. ADB
populations need to be monitored closely during bloom to determine if fiuther sprays are
required during this critical period.
The standard method of blossom tapping is the most reliable method of monitoring ADB,
yielding much higher numbers of ADB than sticky white traps.
Many factors affect ADB populations, including temperature, rainfall, wind, orchard design
and cultural practices. Once large numbers of ADB have moved into an orchard they remain
there in high numbers for several weeks post petal fall ( until codling moth cover sprays
commence).
Apples are vulnerable to attack from ADB between the phenological stages of bud separation
to one week post petal fall. Most damage occurs between early pink and petal fall. The most
critical period for damage resulting from ADB attack is 2% bloom to 60% petal fall.
ADB shows a preference for flowers at fiill bloom.
Fruit damaged by ADB is shed preferentially, reducing yield.
Plague thrips {Thrips imagins) cause damage to developing fiîit that is difficult to distinguish
from minor ADB damage . Thrips damage to apple stalks may reduce yield.
ADB damage can be confirmed, if when dissected there is evidence of core or vascular bundle
distortion connected to the base of the dimple.
The morphological evidence suggests that ADB feed on the juices conducted by the vascular
tissue in the ovary of the flower. When the internal morphological evidence is aligned with
the apparent preference for open flowers, it is possible that ADB feeds on the vascular tissues
that supply nectar to the nectaries in the open flower. In this sense ADB may be tapping into
the nectar flow below the flower.
Page 88
TECHNOLOGY TRANSFER
Publications
Bower, C.C. 1992. What blossom stages are most susceptible to apple dimpling bug?
Fruitwise 11. 17-18
Dray, D. 1993. Apple dimpling bug's gourmet diet. Fruitwise 15. 6.
Seminars
Bower, C.C. 1992. New insights into apple dimpling bug. Pest and Disease Management
Seminar, Batlow, 3rd September 1992. (NSW Agriculture and Batlow Fruit
Cooperative Ltd., Batlow).
Bower, C.C 1992. New insights into apple dimpling bug. Growers meeting in Orange, NSW.
16th September 1992.
1991
Cropwatch seminar, Victoria
1992
Responsible pest management committee Field Day, Shepparton, Victoria
1991
Grower meeting- Management of Apple dimpling bug, Queensland
Grower services
ADB warning service to apple growers, Western Australia
ADB warning service to apple growers (local radio and newspaper, Hort. Infoline
Page 89
RECOMMENDATIONS
Spraying wattles etc that surround orchards may reduce the risk of ADB attack.
Further studies of populations in pastoral areas and weather systems may show what
triggers migration and allow prediction of what numbers in pastoral areas may cause
damage on apples.
Further investigation of the resistance mechanisms in Jonathan and Pink Lady
may lead to a selective breeding program to combat ADB damage levels in apples.
Chlorpyrifos is a suitable choice for prophylactic application at pink bud stage, but
careful monitoring of pest populations is required so that growers can decide if
additional sprays are needed during blossoming. Chlorpyrifos applied while bees were
foraging resulted in bee deaths up to two days after application.
Further studies are needed to determine the efficacy and side effects of programs
involving chlorpyrifos applied at pink followed by extra applications of either
endosulfan or fluvalinate during bloom.
The standard method of blossom tapping is the most reliable method of monitoring
ADB.
The critical period for protecting fruit is from pink bud stage to one week after petal
fall.
Yield is reduced by severe ADB damage and thrips damage to apple stalks.
Dissection of damaged fruit revealed patterns of internal damage caused by ADB.
The pre-bloom to post-bloom period is critical for the control of a number of other
pests in addition to ADB. An IPM strategy needs to be developed that integrates the
control of scab, loopers and budworms, ADB and first generation codling moth which
in turn establishes the pattern of control options for the remainder of the growing
season.
Page 90
ACKNOWLEDGMENTS
The authors would like to thank the following growers and research institutes who allowed
unrestricted access to their orchards, packing sheds and equipment:
B.Apted
Mr J Baronio
J & M Cairns
Mr Neil Cook
Mr J. Devereux
Mr G Frankhauser
Bathurst Agricultural Research Station
Granite Belt Horticultural Research Station
Stoneville Research Station
Biometric assistance and advice was provided by:
Mr D. Butler
G. Hepworth
Mrs A. Kelly
Mrs H. Nicol
Technical assistance was provided by:
Mrs Anne Hately
Mrs Marion Eslick
Mr W Rye
Mr R Legg
Mr Mark Sivyer
Mr Peter Nimmo
NSW
NSW
Victoria
Victoria
Western Australia
Queensland
The project could not have been completed without the assistance of a number of Casual
Scientific Assistants:
Ms Edith Costella
Western Australia
Mr Patrick Walsh
Micaele Antoine
Mr SamScalora
OwenSeeman
Western Australia
Western Australia
Queensland
Queensland
Our thanks go to Mrs Jill Turpin for the typing of parts of this report.
Page 91
LITERATURE
Bodnaruk, K.P. (1992). Daily activity patterns of adult Creantiades dilutus (Stal) and
Campylomma liebknecti (Girault) (Hemiptera: Miridae) in early flowering cotton. J.
Aust.Ent.Soc 29:177-181
Boivin, G, Stewart, RK, and Rivard, I. 1982. Sticky traps for monitoring phytophagous
mirids (Hemiptera:Miridae) in an apple orchard in south-western Quebec.
Environmental Entomology No. 5. pp 1067-1070.
Bower, C.C, Nichol, H.I., and Valentine, B.J. (1993). Variable spray threshold for apple
dimpling bug, Campylomma liebknechti Girault (Hemiptera: Miridae) on apple. Pest
Control & Sustainable Agriculture. CSIRO: pp 142-145
Bower, CC, Thwaite, WG. 1986. Integratedcontrolof pests of apples. Agfact H4.AE.4. 2nd
edn. 4pp. Department of Agriculture, New South Wales.
Chinajariyawong, A and G.H. Walter (1990). Feeding biology of Campylomma livida Renter
(Hemiptera: Miridae) on cotton, and some host plant records. J. Aust. Ent. Soc 29 :
177-181
Coli, WM, Green, TA, Hosmer, TA, Prokopy, RJ. 1985. Use of visual traps for monitoring
insect pests in the Massachusetts apple IPM program. Agriculture, Ecosystems and
Environment. 14,251 -265.
Evans, J.W. 1933. A simple method of collecting thrips and other insects from blossom.
Bulletin of Entomological Research 24. 349-350.
Lindsay, S, et al. 1995. Deciduous Fruit Crop Protection Guide-1995. Queensland
Department of Primary Industries, pp 3,59.
Lloyd, N.C. (1969). The apple dimpling bug Campylomma livida Reut. (Hemipter: Miridae)
Agric. Gazette. N.S.W. 80 :582-584.
Malipatil, m (1992). Revision of Australian of Campylomma Renter (Hemipter: Miridae)
Phylinae. J. Aust. Ent. Soc. 92: 357-368
Prokopy, RJ, Hubbell, GL, Adams, RG, Hauschild, KI. 1982. Visual monitoring trap for
tarnished plant bug adults on apple. Environ. Entomol. 11,200-203.
Prokopy, RJ and Owens, ED. 1978. Visual generalist with visual specialist phytophagous
insects: host selection behaviour and application to management. Ent. exp. & appl.
24:409-420. Ned. Entomo Ver. Amsterdam.
Sivyer, M (1990). Apple dimpling bug.
farmnote 74/90. Ipp
Western Australia Department of Agriculture
Thwaite, W.G. (1982) Apple dimpling bug.
Agriculture. 2pp.
Page 92
Agfact H4.Ae.2 NSW Department of
Thwaite, WG, Gordon, R, Penrose, LJ, Withey, RK. 1994. 1994/95 Orchard Plant Protection
Guide for Inland New South Wales. p.61.
Vogt, WG. 1992. Calibration of trap catches and net catches for estimating population
densities of the bush fly Musca vetustissima (Diptera:Muscidae). Bulletin of
Entomological Research (1992). 82,539-546.
Page 93

AP003 Management of Apple Dimpling Bug Dr Colin Bower

Transcription

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