Biology and management of Polygala myrtifolia

Biology and management of Polygala myrtifolia

Biology and management of
Polygala myrtifolia
Robin Adair
Australis Biological
Latrobe University, Botany Department
www.australisbiological.com.au
Background
 Australis Biological
 Weed Sciences – Research Leader
 Polygala – 1996
 IX International Sym on Biocontrol of Weeds
 1998 - Chrysanthemoides
 1999-2004 – Acacia, Victorian Coastal Council - $5000
 2009-2012 – City Greater Geelong
Building an understanding of Polygala
Essential for effective management
Strengths and weaknesses
Focus on weaknesses - control
Understand the strengths – resilience
Build effective control options
Biology, ecology (native and non-native), control options, integrated control
Taxonomy
Polygala myrtifolia
• Polygala is Greek meaning ‘much’ ‘milk’
- reputedly promotes secretion of milk by stock
• myrtifolia similarity to myrtle leaves
• Polygalaceae - 13 genera , 830 species
• (related to Tremandraceae, not Fabaceae)
Bredemeyera (6)
Salomonia (1)
Comesperma volubile (24)
Polygalaceae
 Polygala is the largest genus – 300-725 species
 cosmopolitan (except NZ, Polynesia, Antarctica)
 centres of diversity – South Africa, Americas
 South Africa/Madagascar – 230 spp
 Australia – 44 native to northern Australia
 annuals
 5 exotic species
 P. myrtifolia, P. virgata, P. vulgaris (Victoria)
 P. japonica (native)
P. chamaebuxus grandiflora
P. senega (Americas)
P. vulgaris - Europe
P. calcarea - Britain
P. cruciata - USA
P. sanguinea USA
P. pauciflora - USA
P. alba - USA
Polygala japonica
P. isingii
lateral petals
wings
(lateral sepals 2 )
crest
keel (petal)
P. obscura – New Mexico
crest
(a)
(b)
Polygala virgata
P. myrtifolia var. myrtifolia
P. myrtifolia var. grandiflora
P. myrtifolia – myrtle-leaf milkwort, Bellarine pea, boukappie, septemberbossie
• South African – uncommon in wild, common in horticulture
• high variability in South Africa
• not weedy in South Africa
• very weedy in Australia
• coastal vegetation at risk
potential
current
P. myrtifolia – Betty’s Bay
Ocean Grove 2010
Invasion history
•
•
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•
•
Earliest record - nursery catalogues in Adelaide, 1845
First collection – NSW , Hasting River ,1856
South Australia the first collection, Adelaide, 1920
Western Australia, Katanning, 1901
Tasmania, Taroona, 1946
•
•
•
•
•
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In Victoria, was introduced to Mt Eliza, 1851
First herbarium collection - Brighton and Mentone, 1886
Bellarine Peninsula, the earliest record is Point Lonsdale, 1912
Mornington Peninsula, naturalization well established by 1943
Not established until 1950s–1960s
South-western Victoria, well-established prior to 1976
Invaded Discovery Bay Coastal Park from a hedge on private land
Earth moving equipment may have exacerbated spread, particularly along boundary
firebreaks
Spread rapid 1981 and 1990
A major threat to biodiversity values
•
•
Impacts
• loss of biodiversity - competition and allelopathy (no evidence)
• increased biomass and fire-fuel levels (no evidence)
• reduced accessibility
• no threat to agriculture
• host to Cucumber Mosaic Virus – threat to vegetable and
ornamentals
State
Impacts
Vegetation communities invaded
Species and vegetation communities at risk
Volcanic Plains Bioregion: Heathy Dry Forest, Heathy
Woodland, Coastal Dune Scrub, Coastal Headland Scrub,
Coastal Tussock Grassland, Coastal Alkaline Scrub,
Lowland Forest
Otway Plain Bioregion: Coastal Saltmarsh, Grassy
Woodlands, Coastal Tussock Grassland, Coastal Dune
Scrub and Grassland Mosaic, Bellarine Yellow-Gum
Woodland , Limestone Grassy Woodland
Warrnambool Plain Bioregion: Herb-rich Foothill Forest,
Coast Banksia Woodland
Gippsland Plain Bioregion: Moonah Woodland
Glenelg Plain Bioregion: Heathy Woodland, Damp Sands
Herb-rich Woodland
Heathy Herb-rich Woodland
Highlands - Southern Fall Bioregion: Riparian Forest,
Dry Forest
Wimmera: Low Rises Woodland
Acacia uncifolia, Adriana quadripartitia, Caladenia calcicola,
Caladenia insularis, Caladenia colorata, Corybas despectans,
Eucalyptus leucoxylon ssp. bellariensis, Poa poiformis var.
ramifer, Prasophyllum litorale, Prasophyllum spicatum,
Pterostylis cucullata, Taraxacum cygnorum
South
Australia
Allocasuarina verticillata Woodland, Eucalyptus
camaldulensis var. camaldulensis Woodland, Eucalyptus
diversifolia ssp. diversifolia Mallee Forest, Eucalyptus
diversifolia ssp. diversifolia Mallee Woodland, Eucalyptus
fasciculosa (mixed) Woodland, Eucalyptus fasciculosa
Woodland, Eucalyptus goniocalyx ssp. goniocalyx (mixed)
Woodland, Eucalyptus obliqua (mixed) Woodland,
Eucalyptus obliqua Woodland, Leucopogon parviflorus
(mixed) Shrubland >1m, Melaleuca brevifolia Shrubland
>1m, Melaleuca halmaturorum Shrubland >1m,
Melaleuca lanceolata Shrubland >1m, Melaleuca
lanceolata Woodland, Olearia axillaris Shrubland >1m
Acacia enterocarpa, Acacia pinguifolia, Acacia whibleyana,
Acacia rhetinocarpa, Caladenia tensa, Caladenia argocalla,
Caladenia behrii, Caladenia colorata, Caladenia
richardsiorum, Caladenia rigida, Caladenia formosa, Correa
calycina var. calycina, Dodonaea procumbens, Glycine
latrobeana, Haloragis eyreana, Ixodia achillaeoides ssp.
arenicola, Olearia pannosa ssp. pannosa, Pleuropappus
phyllocalymmeus, Pomaderris halmaturina ssp. halmaturina,
Prasophyllum frenchii,
Prasophyllum pallidum, Prasophyllum pruinosum,
Prostanthera calycina, Pterostylis cucullata, Pterostylis
arenicola, Pterostylis tenuissima, Ptilotus beckerianus, Senecio
macrocarpus, Stackhousia annua, Taraxacum cygnorum,
Thelymitra epipactoides
New South
Wales
Coastal Headland Scrub, Dry Dune Shrub Forest,
Estuarine Wetland Scrub, Coastal Foothills Dry Shrub
Forest
Acacia georgensis, Chamaesyce psamogeton, Correa
baeuerlenii, Dracophyllum oceanicum, Pultenaea pedunculata,
Prostanthera densa, Senecio spathulata var. attenuatus
Victoria
Communities: Coastal Moonah woodland, Bellarine YellowGum Woodland, Limestone Grassy Woodland, Wimmera Low
Rises Woodland
Communities: Bangalay Sand Forest, Eastern Suburbs Banksia
scrub, Swamp Oak Floodplain Forest, Themeda Grassland (seacliffs and coastal headlands)
Western
Australia
Eucalyptus diversicolor Tall Forest, Eucalyptus calophylla
Forest-Woodland, Agonis flexuosa Woodland, Eucalyptus
marginata Woodland, Dryandra Open Heath, Dense
Coastal Heath, Eucalyptus gomphocephala Woodland,
Eucalyptus patens Woodland, Melaleuca thicket
Asplenium obtusatum subsp. northlandicum, Caladenia
busselliana, Caladenia caesarea subsp. maritima, Caladenia
procera, Caladenia viridescens, Caladenia procera, Caladenia
viridescens, Chorizema varium, Wurmbea calcicola
Communities: Agonis flexuosa Woodland
Tasmania
Dry coastal vegetation, Allocasurina forest, Acacia
longifolia scrub, Melaleuca ericifolia scrub, Stabilised
dune communities, Coastal Myoporum insulare scrub
Brachyloma depressum, Lasiopetalum baueri, Pomaderris
oraria, Veronica plebia, Zieria littoralis
Status of Polygala
• currently undeclared any where in Australia
• NWR Phase 3b
- two Vic CMAs recommended regionally controlled
- all other Vic CMAs recommended restricted
• 3b Proposal - restricted in Victoria - abandoned
• South Australia – listing proposed
• control implications
Management options
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•
hand pulling
herbicides
fire
biological
integrated control
Hand pulling – difficult for large plants, tedious for small plants
– effective
– new incursions, isolated plants, sterile plants
Herbicides
Fire
Biological
– susceptible
– cut and paint
– metsulfuron methyl is effective, high non-target impacts
– glyphosate is effective on both seedlings and mature plants
– picloram-based gel on freshly cut stumps is effective
– fire-sensitive, high intensity fires are required
– suppression of hot summer fires - contributed to expansion
– canopy scorch needed
– low herbivory in Australia
– potential realised in 1996
– published 2010 (www.australisbiological.com.au/publications)
– strong field of candidates
Biological control
Duffoemyidia barkeri (longicorn beetle)
Diaphorina petteyi (flower psyllid)
Cossidae red crown-moth
Lasioptera sp. (shoot gall midge)
A
C
D
Agromyzid (leaf miner)
Aceria myrtifoliae (gall mite)
Uredo polygaliae (rust fungus)
Seedling regeneration following
removal of adults
Control options:
Hand-pulling?
Herbicides?
Fire?
Natural events?
Point Nepean, Victoria
Predicting control scenarios
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modelling - help select best control methods
population responses
need data - construct population models
knowledge gaps – many
e.g. seed longevity, soil-seed bank, seedling
behaviour
• DPI/CGG/CfOC partnership – 2011
• useful for implementation
Buckley Reserve project
a study designed to address knowledge gaps
Buckley Reserve, Ocean Grove
Buckley Reserve, Ocean Grove
What data was collected
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plant densities
age profiles
phenology
seed bank behaviour
seedling survivorship
seed fall
post dispersal seed losses
cleared vs canopy responses
uncleared
cleared
uncleared
cleared
Population structure – Ocean Grove 2010
120
infertile
100
fertile
Number of plants
80
60
40
20
0
1
< 1mm
2
1-5 mm
3
6 -10 mm
4
11- 50 mm
5
>50 mm
Figure 8. Numberof Polygala myrtifolia seeds in soil from cleared (triangle) and uncleared
(circle) plots. Data are mean number of seeds 950 cm-3
20
18
16
14
Number of seeds
[
12
10
8
6
4
2
• persistent seed bank
0
• clearing triggers seed bank depletion
P. myrtifolia seedlings on cleared and control plots.
Bar colours represent age cohorts over four seasons.
• high emergence on
cleared plots
cleared
Number of seedlings
1400
1200
• large losses over
summer
1000
• Most germinate
winter spring
800
• higher survivorship
under canopies
600
400
200
0
200
1
09/09
2
12/09
3
03/10
4
06/10
canopy
Number of seedlings
180
160
140
120
100
80
60
40
20
0
09/09
1
2
12/09
3
03/10
4
06/10
Accumulative germination of fresh P. myrtifolia seed
80
% germination
70
60
50
40
30
20
10
0
0
10
20
30
• high levels of viability in fresh seed
• germinates rapidly under ideal conditions
• very little innate dormancy
40
50
Days
60
70
80
90
100
Seed collection trap
Rat exclusion fence
eliasome
High levels of seed mortality
occur after seed fall
pigeons (turtle doves, rats)
Ants carry seeds short distances
and cache seeds
High level of fertility
Most flowers are fertile and produce 2 seeds
Flowering/fruiting is very seasonal
40
buds
flowers
fruit
35
% Frequency
30
• strong
25
seasonality
20
• short peak
period
15
10
5
0
06/09
07/09
09/09
10/09
11/09
12/09
01/10
02/10
03/10
04/10
05/10
06/10
200
180
flowers
Total number
160
140
• low seed
120
output
seeds (in traps)
100
• high flower
failure (verify)
80
fruit
60
40
20
0
06/09
07/09
09/09
10/09
11/09
12/09
01/10
02/10
03/10
04/10
05/10
06/10
Modelling
• Quick method - comparing different control options
• 6 months to develop
• Can run for any control method - press of a button
• Cut down years of trialling each control method
• Technology is available for realistic model (Stella software)
• Can test how well the model mimics real life
• Availability of information of Polygala population dynamics
model of a plant lif e cy cle
se eds mo ve in
fre sh
see ds
se eds
i n soi l
ac cumi l atio n
se ed ag ei ng
ge rmi na ti on 1
ge rmi na ti on 2
se edl i ngs
se edl i ng de ath
growth1
j uven il es
j uven il e de ath
growth2
ad ul ts
ad ul t de ath
mon th
pre pred atio n ra te
po st p re dati on rate
max thresh ol d1
se ed pred atio n
se ed de ath
fin al s eed
fre sh
see ds
se eds mo ve in
se ed
soi l b ank
se ed ac cumu la te
se eds c arryi ng
cap aci ty
month
se ed vi abi l ity
ca nop y
se ed pred atio n
ad ul t ev al uater
Cotyle don ous
see dl in gs
i ni ti al adu lts
ca nop y
fire effect2
ge rmi na ti on 1
ge rmi na ti on 2
su mmer stre ss
su mmer s tres s
se edl i ng thi nni ng
grow th
fire effect1
growth
i ni ti al adu lts
Gra ph 1
fire effect1
m o nt h
+
p re p re da ti on r at e
s ee d lin g sm o v in g
p os t pr ed a tio n ra te
T ab le 1
se edl i ng co ntro ll er
m a x th re sh o ld 1
s ee d p re da ti on
s ee d d ea th
fi na l se e d
o ut pu ts
ad ul t ev al uater
s ee d
fr es h
s o il ba n k
s e ed s
Adu lt
+
+
s ee d a cc u m ul at e
s ee d s m ov e in
s ee d s ca rr yi ng
c a pa c ity
T ot al J uv e ni le s
T ot al See d lin g s
m o nt h
s ee d v ia bi lit y
c an o py
+
s ee d p re da ti on
T ot al p op u la tio n
a du lt e va lu a te r
Cot yl ed o no u s
s e ed li ng s
in it ia l a d ul ts
fi re e ffe c t2
g er m in at io n 2
c an o py
g er m in at io n1
s um m e r st re ss
fi re e ffe c t
fi re e ffe c t3
s um m e r st re ss
s ee d lin g th in n in g
g ro wt h
fi re s ta tu s
g ro wt h
fi re tim e
fi re e ffe c t1
in it ia l a d ul ts
fi re e ffe c t1
s ee d lin g c on tr ol le r
a du lt e va lu a te r
fi re e ffe c t2
fi re e ffe c t1
See d lin g s
s ee d lin g
b a nk
s ee d lin g a cc u m ul at io n
s d yr 6
s d yr 5
m6
d6
d4
m1
d1
d2
d3
d5
s ee d lin g d ea th 2
s ee d lin g de a th
m2
m3
m4
m5
s d yr 1
s d yr 2
s d yr 3
s d yr 4
fi re e ffe c t1
ju v en il e de a th 2
fi re e ffe c t1
J uv e ni le
b an k
ju v en il e ac c um u la ti on
s d yr 7
s d yr 8
m7
ju v en il e
s d yr 10
m11
m10
d8
d9
ju y r1
s d yr 11
m9
m8
d7
s d yr 9
m12
d 10
ju y r3
ju y r2
g1
ju y r6
jd 6
jd 5
jd 3
jd 7
ju y r1 0
ju y r9
ju y r8
g9
g7
g6
g5
g4
jg 2
jd 1
ju y r5
ju y r4
g3
g2
d 11
jd 1 0
g8
jd 8
jd 9
ju v en il e
g 10
d e at h
jd 1 7
jd 1 8
jd 2 1
jd 2 2
fi re e ffe c t1
in it a du lt s
Adu lt
jd 1 4
ju y r1 8
ju y r2 1
fi re e ffe c t1
ju y r1 3
ju y r1 4
ju y r1 7
g 13
g 17
ju y r2 2
ju y r1 2
jd 1 2
g 14
g 18
g 20
in it ia l a d ul ts
th in n in g
fi re e ffe c t1
jd 1 9
jd 2 0
jd 2 3
p ro d uc ti on
c an o py s ta tu s 1
fi na l se e d
a du lt a gi ng
Adu lt
fi re e ffe c t2
m a x se e d
m o nt h
p ro du c tio n
c an o py
m a x se e dl in gs
s ee d m o ve o u t
fr es h
Adu lt
s ee d m o ve o u t
s ee d lin g c on tr ol le r
fi re e ffe c t3
ju y r1 5
g 15
ju y r2 3
g 24
s ee d
ju y r1 6
g 19
Adu lt
s e ed s
ju y r1 9
ju y r2 0
a du lt e va lu a te r
BC ef fe ct
g 16
g 22
s el f
fi re e ffe c t3
fi re e ffe c t1
jd 1 6
jd 1 5
ju y r1 1
g 11
g 12
jd 1 3
g 21
jd 1 1
What does the model do?
We can compare the effects of different
control methods
e.g. biocontrol by seed predator
Scenario 1 - 90% of seeds eaten
Scenario 2 - 50% of seeds eaten
See model details @
(http://forio.com/simulate/ratnapriya.gajaweera/polyga
la-hispeed/run/)
Model Results
control
Cossidae + 50% seed
Cossidae
Cossidae + 90% seed
fire
fire + 90% seed removed
Key Points
 high post dispersal seed mortality – pigeons and rodents
 seed banks are short-lived (5-10 yrs)
 soil pathogens and drought – kill seedlings
 high seedling mortality (summer)
 rapid seed bank depletion when canopy is opened
 2 yrs to sexual maturity
 plants are susceptible to herbicides
 control activities easier after natural thinning
 a combination of control options is better than 1 alone
Acknowledgements
City of Greater Geelong
Caring for our Country Program
Barwon Coast Committee of Management
Bev Wood
Troy Gallus
Glenelg-Hopkins CMA