Issue Number: 02
Date: 23/05/2014
PestFax
PestFax is a weekly informative and interactive reporting service,
providing risk alerts, current information and advice on pests and
diseases threatening crops and pastures throughout the grain belt of
Western Australia (WA).
PestFax is supported by the National Invertebrate Pest Initiative (NIPI) a Grains Research and
Development Corporation (GRDC) project that promotes national pest management information
and Integrated Pest Management (IPM) principals.
Newsletter of the Department of Agriculture and Food, Western Australia
Contents
Mites and lucerne flea
Canola downy mildew
Barley net blotches
Airborne spores of barley diseases
Weevils
Caterpillars
Slugs and snails
Slaters
African black beetle
Field pea blackspot
Mice
Mites and lucerne flea
In many parts of the WA grainbelt immature sized bryobia mites, lucerne flea, and redlegged earth
mites are being found attacking crops and pastures. These pests hatched from their oversummering dormant eggs following rainfall four weeks ago (Anzac weekend) and two weeks ago
(8 May 2014 rain fronts). Rainfall last spring provided excellent growing conditions for crops and
pastures but equally provided favorable conditions for development of large pest populations that
carried-over to this autumn.
The hatching and appearance of redlegged earth mites (RLEM) was either delayed or only
partially occurred in northern and other grainbelt areas as temperatures accompanying the earlier
rains were not quite cold enough to satisfy the mite’s biological requirements. RLEM are known to
require rainfall followed by a period of cool temperatures (5–7 days <20°C max temperature)
before they will hatch.
Reports into PestFax have confirmed that the redlegged earth mites are now being seen in
widespread localities. Sizes vary with about 20-30% being easily visible whilst a larger proportion
is about ‘half sized’ mites and others being even smaller. This indicates that the hatching of the
mites occurred following favourable weather patterns on a least two separate occasions.
Where needed, insecticides are being applied to some seedling crops in conjunction with post
emergent weed control whilst other paddocks, yet to be sown, are having an insecticide
incorporated with the knock-down herbicide. These control measures are timely, as in most cases
they are being applied before the mites reach adult size and commence to lay their winter eggs,
which give rise to the next generation.
Helen Lethlean (Farmworks Moora) reports that hatching of RLEM has occurred throughout the
West Midlands region. Lucerne flea are being easily found on most paddocks between Gillingarra,
Moora, Watheroo, Badgingarra and Dandaragan on loam/clay soil types which typically favour the
pest.
Rob Alderman (Landmark) reports that lucerne flea are causing damage to some canola and
cereal seedling crops in the Geraldton region on loam/clay soil types especially on crops he has
seen near Nabawa and Walkaway. Many of these crops were sown into cereal stubbles and were
not expected to have the current pest levels of lucerne flea.
Five agronomists reported to Department of Agriculture and Food, Western Australia (DAFWA)
staff that lucerne flea have been troublesome on canola and cereal crops over widespread areas
within the Northern Agricultural Region on paddocks with clay loam soils which favour the pest.
Crops on red loamy soils in the Morawa, Three Springs and Carnamah areas and clay areas
around Dalwallinu and Yandanooka were noted for increased levels of the pest. Early sown
crops with unacceptable levels of lucerne flea damage have been sprayed with appropriate
insecticides incorporated into the post-emergent weed control spray application. Another
agronomist reported that bryobia mites have caused damage to seedling canola, especially on
some paddocks with sandy soil types south west of Carnamah.
Ty Henning (TekAg) reports finding RLEM this week on pasture paddocks between Badgingarra
and east Dandaragan. The mites were of varying sizes. Some clover based pastures in 2013
have very high levels of mites that are now being sprayed. Ty also observed blue oat mites,
bryobia mites and lucerne flea along with the RLEM. He says that lucerne flea have been very
damaging to some seedling crops and pastures including a lupin crop he saw this week north east
of Cadoux.
Eloise Dean (Elders) reports finding lucerne flea at low levels across the Wongan Hills district,
mainly on the heavier textured soils. They are causing noticeable damage, but crops (particularly
canola and lupins) are growing well and are not requiring spraying at this time. Growers plan to
apply an insecticide with early post emergent applications of herbicides to control the pest
numbers where required.
Brent Pritchard (Farmanco) reports that there have been widespread hatchings of earth mites on
the coastal strip of the great southern. Blue oat mites have been seen west of Mt Barker. So far
Brent has observed only low levels of damage to canola with crops generally out growing any
damage. Brent has also reports of lucerne flea at Borden on red-grey loams that caused
significant damage to canola and have been sprayed with an organophosphate (OP).
Farmers at Narrikup and South Stirling reported that emerging clover and canola crops were
being damaged by earth mites and required spray control.
Quenten Knight (Precision Agronomics) reports finding large numbers of juvenile RLEM 30
kilometeres (km) east of Esperance. The mites severely damaged a paddock of 1–2 leaf Dargo
ryegrass and serradella pasture before being sprayed with omethoate. Andrew Heinrich (Farm and
General) commented that in the Esperance area, numbers of RLEM seem less noticeable this
week than last week, possibly due to the warm and dry conditions that have been experienced this
week in the area.
Ashton Gray (ConsultAg) reports that RLEM have caused extensive damage to a one leaf barley
crop growing East of Brookton. As many as 50 mites can be seen on some of the single leaf
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blades with others having 10 to 30 mites per leaf. The sucking damage from this level of mites in
patches of the crops has resulted in around 50% of the leaf surfaces bleached / silvered a whitish
colour from the collapse of leaf cells and removal of chlorophyll. The mites which are currently
immature have been sprayed to prevent even further damage or plant death before they reached
their fully grown adults.
Cara Allen from the University of Western Australia (UWA)/Western Australian No-Tillage Farmers
Association (WANTFA) reports that she detected immature redlegged earth mites and blue oat
mites on the WANTFA trial site pasture plots at Cunderdin last week.
David Stead (Anasazi Agronomy) reports that redlegged earth mites are being more readily seen
this week in central western areas including York, Northam, Cunderdin and Tammin. David also
reports that high levels of lucerne flea are causing extensive damage to some germinating and
seedling crops in the Avon Valley. The lucerne flea are mostly found on risk paddocks which did
not receive an appropriate seed treatments or pre-sowing insecticides and were in pasture or
canola during 2013. Large numbers of bryobia mites are also attacking cereal crops in parts of the
Avon Valley area. The high numbers and damage is most noticeable on last year’s pasture
paddocks. David also reports similar damaging levels of bryobia mites north of Corrigin and near
Quairading.
Scott Thomson (central AG) reports that lucerne flea are infecting young canola seedlings north of
Goomalling. No insecticides were applied prior to seeding but will now be applied.
Dan Taylor (DKT Rural) reports that a number of canola seedling crops and an occasional cereal
crop in the Kellerberrin, Doodlakine and Tammin areas have required spraying to control
damaging numbers of lucerne flea. These cases have all been on the heavier type clay soils
known to favour the survival and increase of lucerne flea.
Dani Whyte (Landmark) reports that RLEM are being found in the Merredin area often along with
bryobia mites. Dani has also been finding low levels of bryobia mites on cotyledon to four leaf
canola in the Nukarni area (Nth Merredin). Lucerne flea has also been causing damage to some
seedling crops south of Merredin.
Clare Hyde (Synergy Consulting) reports finding lucerne flea damage on volunteer barley near
Holt Rock. Also an emerging canola crop in the area required spraying last week to control
damaging levels of bryobia mites and weevils.
A farmer near Babakin reported lucerne flea damage to his wheat and barley crops. Damage is
more severe in the crops planted into last year’s pasture paddocks in areas with clay loam and
gravelly loam soils. These areas are being sprayed to control further damage.
For further information see last week’s PestFax Issue No.1 16 May 14 and the following links –
Diagnosing lucerne flea, Diagnosing redlegged earth mites and Diagnosing bryobia mite
Insecticide control failure
A growing number of WA cropping properties (more than 26) have been identified has having
RLEM that are resistance to high rates of synthetic pyrethroid (SP) chemicals such as bifenthrin
and alphacypermethrin since the first discovery of this resistance in WA in 2006. Many of the
growers who had laboratory testing of their mites to confirm this resistance are now managing
their paddocks to successfully limit and prevent spread of these mites over their paddocks.
Growers and agronomists who observe surviving RLEM following applications of insecticides such
as bifenthrin or alphacypermethrin should take advantage of a free testing service this year to
determine the resistance status of their mites. The testing service is funded by GRDC in 2014/15
and is conducted by DAFWA researchers in collaboration with CSIRO, UWA and cesar Victoria.
To take advantage of this free service contact –
Svet Micic, DAFWA Albany
Email: svetlana.micic@agric.wa.gov.au
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Phone: +61 (0)8 98928591 or +61 (0) 427 772 051
Peter Mangano DAFWA Perth
Email: pmangano@agric.wa.gov.au
Phone: +61 (0)8 9368 9753 or +61 (0) 404 819 534
For further information see the following links – Diagnosing redlegged earth mites and Prevent
redlegged earth mite resistance
Canola Downy Mildew
There have been many reports of downy mildew infection to canola seedlings this week,
particularly in the central and great southern areas.
Xavier White (grower) reports seeing severe downy mildew causing substantial seedling mortality
on his volunteer canola in Wagin. Another grower reported widespread damage to his canola
crops at Brookton. Ashton Gray (ConsultAg) reports wide spread occurrence of downy mildew in
the Great Southern region. Doug Sawkins (DAFWA, Narrogin) reported seeing downy mildew on
volunteer canola north east of Cuballing.
Scot Thomson (Central Ag) reports that he is finding widespread downy mildew infection in young
(cotyledon -2 leaf) canola, in the Goomalling and surrounding area. He noted that triazine tolerant
(TT) varieties seem to have the heaviest infection. Canola treated with Jockey, and Flutriafol in
furrow seem to have the lowest infection . Dan Taylor reports seeing downy mildew and/or
‘damping off’ symptoms on canola seedlings in the Kellerberrin, Doodlakine and Tammin areas.
Danni Whyte (Landmark) reports seeing a few scattered canola seedlings in the Nangeenan area
affected with downy mildew. At that location the disease is having minor impact and mainly
affecting small cotyledons.
David Cameron (Farmanco) reports finding downy mildew in a canola crop and on wild radish near
Bindi Bindi. Susie Mason (Elders) reports seeing downy mildew on canola from the cotyledon to
two leaf stage in crops around Dandaragan. In older plants it was quite severe and in some cases
the cotyledons were nearly gone due to the disease. Eloise Dean (Elders) reports finding downy
mildew in cotyledon — four leaf GM canola and TT canola crops north of Cadoux and east of
Ballidu, most of the downy mildew is on the cotyledons with very small amounts on the first true
leaves.
Stuart Witham (Agronomist) reports finding downy mildew on canola from Jacup and on volunteer
canola near Frankland.
Plant Pathologist Ravjit Khangura says that the symptoms of downy mildew appear mostly as
yellowed cotyledons and lower leaves. Examination of the underside of these leaves often shows
a corresponding patch of grey/white fluffy growth, although this can become less apparent with
age. The disease mainly affects the seedlings and the upper leaves (third and fourth leaves) are
usually healthy looking. This season weather conditions (frequent rain coupled with conducive
temperature, high humidity and cloudy days) have been perfect for the early onset of downy
mildew.
Ravjit commented that downy mildew is either soil/ seed borne or requires a green bridge for carry
over. Disease spread is generally favoured by cool moist winter conditions (including heavy dew)
in the early stages of canola growth. Although some early seedling mortality may occur, canola
plants usually overcome the disease once they reach the 5–6 leaf stage and new growth appears
healthy.
Glasshouse trials Ravjit conducted with downy mildew showed that there was very little difference
in susceptibility to the disease over a large number of varieties tested. The fungicide seed
dressing Fluquinconazole (Jockey®) showed some efficacy against downy mildew but Aliette®,
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Copox®, and Benlate® failed to provide adequate protection against downy mildew when applied
on to the seed. Fungicide seed dressings containing metalaxyl (MaximXL®) will provide some
protection against downy mildew. Some copper based products are registered for foliar application
against downy mildew in Brassicas and products containing metalaxyl are registered for Brassica
vegetables in Australia that need to be applied at early signs of infections.
Barley net blotches
Plant pathologist Geoff Thomas reports that several observations have been received to date of
net blotch diseases infecting barley seedlings growing on barley stubble.
David Cameron (Farmanco) reported finding 2–3 leaf stage volunteer barley regrowth heavily
infected with spot type net blotch in Hindmarsh stubble at Coomberdale and Bindi Bindi. Kith
Jayasena (DAFWA) reports similar high levels of spot type net blotch on Buloke regrowth at
Borden and net type net blotch infection in several areas of barley regrowth in the South
Stirlings region.
While these seedlings will be sprayed out prior to seeding of the paddock, they serve as a timely
reminder of the risks associated with stubble borne inoculum of necrotrophic leaf spotting diseases
of barley (spot and net type net blotches, scald), particularly when weather conditions are
favourable for disease development, such as the recent periods of mild temperature and regular
rainfall in many areas.
Last year, significant levels of these diseases were present in many crops and high stubble
burdens have been carried between seasons. Barley sown onto (or adjacent to) barley stubble are
exposed to greater risk of early onset of these diseases, particularly where the disease was
obvious in the previous seasons crop.
Variety selection to reduce risk or being prepared for monitoring and timely application of foliar
fungicides is recommended if sowing barley on barley stubble. An example of a high risk scenario
is sowing Hindmarsh (susceptible to STNB) onto Hindmarsh stubble.
For further information see the managing barley net blotch or managing barley leaf diseases
pages on the DAFWA website (agric.wa.gov.au).
Airborne spores of barley diseases
In a network of spore traps deployed through the South Stirlings region, Kith Jayasena (DAFWA)
has already identified air-borne inoculum of several barley diseases this season. Spores of stem
rust, leaf rust, net botch, spot blotch/root rot, scald and powdery mildew have been detected.
Although regrowth is generally far less advanced than usual in this area, Kith has already seen
barley powdery mildew and wheat stem rust on some volunteer barley regrowth.
The identification of these airborne spores indicates that diseases could again be a risk for cereal
cropping in this region and Kith advises monitoring of emerging crops, particularly susceptible
varieties, and use of registered foliar fungicides if required.
Weevils
Agronomists reported to DAFWA staff that weevils have been in damaging levels requiring spray
control on some seedling canola crops in the Northampton/Binnu area. In other crops damage
levels have been minor (especially with insecticide treated seed) and with good growing conditions
the plants have out-competed the low levels of damage.
Rob Alderman (Landmark) reports that vegetable weevils have caused damage to some seedling
crops in the Geraldton area at levels requiring spray control. The damage on most crops is
relatively minor and confined to crop edges near road reserves and bush lines etc.
David Hurst (Landmark) reports seeing weevil damage on a few canola crops west of Moora this
week. The damage is typical of vegetable weevil with distinctive crescent shaped chew marks and
scalloped edges of leaves and is being found on crop edges. Although a few weevils were found
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David suspects that a combination of factors is likely to have caused the poor establishment of the
canola crop, hypocotyl rot or damping off organisms (see above) may also be causing seedling ill
thrift and deaths.
Dan Taylor (DKT Rural) also reports some weevil damage to canola seedlings near Kellerberrin,
Doodlakine and Tammin.
Helen Lethlean (Farmworks Moora) reports that vegetable weevil and desiantha weevil along with
their damage is being found in isolated pockets of canola crops in the Dandaragan and
Badgingarra areas.
For further information see last week’s PestFax and the link – Diagnosing weevils in canola
Caterpillars
Eloise Dean (Elders) reports finding pasture day moth larvae affecting 1–2 leaf Mace wheat crops
north of Cadoux. The larvae are in the immature stage, 5–10 millimetres (mm) in length but in
high enough numbers to cause concern. Growers will be continuing to monitor the affected
paddocks many of which were in canola in 2013.
Slugs and snails
An agronomist reported to DAFWA staff that increased levels of slugs have been see this year in
areas with heavy soil types in the Moora and Dalwallinu districts. The problem areas within
paddocks for slugs are often known by growers from previous years’ experience and have mostly
been targeted for early applications of snail baits.
Helen Lethlean (Farmworks Moora) reports that large numbers of slugs are causing damage to
canola crops and having to be dealt with by some growers in risk prone paddocks in the
Badgingarra area.
Andrew Heinrich (Farm and General) reports that recent warm/dry conditions in much of the
Esperance area has made small conical snails less active and not feeding on baits spread for
their control. Growers with snail problems are waiting for them to start actively feeding before reapplying baits. He also observed that lower numbers of snails are present in paddocks without a
history of lime applications. Entomologist Svet Micic says that liming paddocks can increase snail
numbers as the additional lime increases the strength of their shells.
For further information on snails refer to PestFax issue No.1 16 May 14 and to the GRDC Snail
Management Fact Sheet and Identification and control of pest slugs and snails for broadacre
crops in WA
Slaters
Jake McGuire (Elders) reports that slaters are damaging volunteer barley near Kojaneerup. Svet
Micic (Entomologist, DAFWA) suggested that pest damage to weeds and volunteer plants in
paddocks should be closely investigated prior to seeding as this provides as good indication of
what will potentially damage an emerging crop.
Svet says that dealing with slaters can be frustrating as although slaters may be found in some
paddocks they often do not cause any plant damage but rather prefer to feed on decaying
vegetation and associated fungi. Crop damage usually only occurs when slater numbers build-up
to high levels of hundreds per square metre. Treating areas of paddocks supporting high slater
populations with snail baits containing methiocarb or iron EDTA baits is often used for control and
now granular products containing bifenthrin are also registered to control slaters. However longer
term solutions need to include paddock management including occasional stubble reduction.
For further info see the DAFWA webpage – Diagnosing slaters in crops
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African black beetle
Jake McGuire (Elders) reports African black beetle adults have caused some damage to a south
coastal cereal forage crop. As there are sufficient surviving plants and the success of the control
options is limited, no sprays will be applied. Trials conducted by Entomologist Stewart Learmonth
suggest that imidacloprid seed dressings provide plant seedlings with some early protection from
African black beetle damage.
For further info see the Diagnosing African black beetles page on the DAFWA website.
Field pea blackspot
Greg Shea (DAFWA) commented that this year’s early break to the season has opened up an
opportunity for some growers to include field peas in their program. The incidence of root lesion
nematodes was high in some cereal paddocks in 2013 and in some situations paddock rotation
with field peas will assist in management of the nematodes.
Greg encourages field pea growers to consider black spot disease risk when deciding how early to
sow their crops. The relative risk of black spot disease in relation to field pea growth stage is
available on the Field pea Blackspot sowing guide for Western Australia page on the DAFWA
website.
Mice
Holly Swarbrick (Precision Ag) reports that canola seedlings growing east of Grass Patch have
been damaged by what seems to be a combination of factors. Some seedlings have definite chew
marks or have been eaten to ground level. Mice have caused part of this damage as is evidenced
by mice holes and their other activity. The damage seems to be in parts of the paddock which has
heavier soil types. Use of pitfall traps will be tried by Holly in an attempt to find any other night
feeding pests.
For more information see last week’s PestFax and the GRDC Mice Control Factsheet, Western
Region
PestFax editor
This issue of PestFax has been provided by a number of contributing DAFWA staff. Due to
unfortunate circumstances the appointment of a new PestFax editor has been delayed.
Enquiries and reports on plant diseases can be directed to:
Bill MacLeod, South Perth
Email: william.macleod@agric.wa.gov.au
Phone: +61 (0)8 9368 3690 or +61 (0)427 986 391
Geoff Thomas, South Perth
Email: geoff.j.thomas@agric.wa.gov.au
Phone: +61 (0)8 9368 3262 or +61 (0)428 947 287
Brenda Coutts, South Perth,
Email: brenda.coutts@agric.wa.gov.au
Phone: +61 (0)8 9368 3266 or +61 (0)419 919 403
Kith Jayasena, Albany
Email: kithsiri.jayasena@agric.wa.gov.au,
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Phone: +61 (0)8 9892 8477
Ciara Beard, Geraldton (Tues, Wed, Thurs Only)
Email: ciara.beard@agric.wa.gov.au
Phone: +61 (0)8 9956 8504
Andrea Hills, Esperance
Email: andrea.hills@agric.wa.gov.au
Phone: +61 (0)8 9083 1144
Enquiries and reports on invertebrate pests can be directed to
Svet Micic, DAFWA Albany
444 Albany Highway
Albany WA 6330
Email: svetlana.micic@agric.wa.gov.au
Phone: +61 (0)8 98928591 or +61 (0) 427 772 051
Peter Mangano, DAFWA South Perth
3 Baron-Hay Court
South Perth WA 6151
Email: pmangano@agric.wa.gov.au
Phone: +61 (0)8 9368 9753 or +61 (0) 404 819 534
Also available on the PestFax page on the DAFWA website:
Crop insects: the ute guide
This book covers crop pests, beneficial insects, biological control, grain storage pests and
biosecurity pest threats specific to WA. Copies are available from some Departmental Offices for a
cost of $10.00 or by mail order by phoning the DAFWA South Perth office on 9368 3710.
Free insect identification
Having troubles identifying mites or other pests? Send in your digital pictures (in focus) or send
live specimens in a non-crushable plastic jar for free identification. Mail to Peter Mangano or
Svetlana Micic at the postal details above.
AgTactic and AgMemo
Other regional DAFWA news updates are available on DAFWA’s website:
agric.wa.gov.au/newsletters
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Growing Season Outlook
Seasonal climate outlooks can available on DAFWA’s website:
agric.wa.gov.au/newsletters/seasonal-climate-outlook-may-2014
AGWEST Plant Labs
Plant disease diagnostic service located at the DAFWA South Perth office. For information on
sending samples and charges contact +61 (0)8 9368 3721 or Fax +61 (0)8 9474 2658 or visit our
website agric.wa.gov.au or agric.wa.gov.au/plant-biosecurity/agwest-plant-laboratories
Next issue of PestFax – 23 May 2014
Copyright © Western Australian Agriculture Authority, 2014
The Chief Executive Officer of the Department of Agriculture and Food and the State of Western Australia accept no
liabilitywhatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it.
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