Issue Number: 16
Date: 29/08/2014
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 Grains Research and Development Corporation (GRDC) and
promotes national pest management information and Integrated Pest Management (IPM)
principals.
Newsletter of the Department of Agriculture and Food, Western Australia (DAFWA).
Contents
Native budworm
Wheat powdery mildew
Barley leaf disease
Oat leaf disease
Armyworm
Lupin aphids
Cereal aphids
Canola aphids
Blue oat mites
Mice
To view a map of pest and disease reports, see PestFax Map and PestFax newsletters for back
copies of PestFax. If you have recently observed or heard news of insect or disease pests in crops
and pastures contact PestFax@agric.wa.gov.au or use the online ‘make an on-line report’ link.
Native budworm
Dan Taylor (DKT Rural) reports that a large increase in the numbers of native budworm
caterpillars has been noticed in canola crops this week south of Doodlakine. Using an insect
sweep net to check crops Dan found numbers ranging from 10 - 40 caterpillars in 10 sweeps, with
sizes ranging from 5 – 12mm long. Dan commented that the numbers of caterpillars being found
now was not really surprising given the large numbers of native budworm moths that were caught
Supporting your success
in a pheromone trap on one of the properties in the area over the past 4 weeks. For the locations
of budworm moth numbers caught in pheromone traps in the last week refer to: Native Budworm
Moth Trap Numbers 2014.
Easterly winds have assisted the movement of native budworm moth flights in recent weeks into
agricultural areas from their origins in northern and eastern pastoral areas. The high levels of
native budworm caterpillars being found this week add to previous reports over the past three
weeks of rising caterpillar numbers being found in northern and central-eastern WA grainbelt
areas. Some advanced northern crops were sprayed in the past week.
Matt Willis (Elders) reports finding very high numbers of native budworm caterpillars in a canola
crop near Mollerin where an average of 110 caterpillars per 10 sweeps was found with sizes of:
10% 0-5 mm, 20% 5-10 mm, 70% >10 mm. Another crop near Cowcowing was found with 35
caterpillars per 10 sweeps with sizes of: 30% 0-5 mm, 50% 5-10 mm, 20% >10 mm. Matt
commented that many canola and lupin crops in the Koorda and Trayning area will need to be
sprayed for budworm in coming weeks. Caterpillar numbers at Wyalkatchem are not as high, but
he expects numbers to increase over coming weeks.
Ty Henning (TekAg) also reports that native budworm caterpillars have been found in large
numbers this week. Canola crops were checked with a sweep net and the following numbers were
found per 10 sweeps: Maya 65, Dalwallinu 30 and Kirwan 70. Most caterpillars ranged from 10 –
15mm long. Ty is concerned that caterpillars may commence to feed on canola pods as crops in
some areas (and soil types) are moisture stressed and have started premature leaf drop due to
the lack of rain. Fortunately diamondback moth caterpillar numbers are very low and not currently
posing a threat.
Farmer and budworm trapper Rob Nankivell reports that he found an average of 3 budworm
caterpillars in 10 sweeps on a field pea crop near Maya and 1 per 10 sweeps on another field pea
crop near Wubin. At both locations caterpillars are currently small with most 5 – 10 mm long.
David Stead (Anasazi Agronomy) reports that budworm caterpillar numbers have increased
greatly in his sweep net monitoring of canola and lupin crops in the Wubin, Dalwallinu, Kalannie
and North Cadoux areas this week. Numbers ranging from 30 – 70 caterpillars per 10 sweeps are
commonly being found in crops.
Monica Field (Farm and General) reports that an average of 1-2 budworm caterpillars is being
detected in sweep net counts of field pea crops in the Grass Patch / Esperance Mallee Region.
These will be sprayed as soon as possible and monitoring for budworm numbers in canola will be
increased.
Canola crops - Native budworm caterpillars only become damaging to canola crops as they
approach maturity, begin leaf drop and commence pod colour change (“hay-off”). It is only at this
growth stage that the valuable canola pods become attractive to the caterpillars (they prefer the
leaf material when it is available). Caterpillars of all sizes will enter pods at this stage, with larger
caterpillars doing the most damage. Native budworm can also cause damage after a canola crop
has been swathed. This will occur if the crop is swathed when many pods are still green with soft
seed. Seed damage from native budworm increases in swathed crops if drying is prolonged due to
cool damp conditions.
Narrow-leafed lupin crops - will not be damaged by native budworm until they are also close to
maturity and the pods are losing their green colouration. Pod walls are not penetrated until the
caterpillars are over 15 mm in length. The decision to spray a lupin crop should not be made until
caterpillars are greater than 15 mm in length and the pods are losing their green colour (when
damage is about to occur). At this stage it will be difficult to use a sweep net as the lupin plants are
stiff and the pods are spiky. An alternative to sweeping is to cut plants from several places in the
crop and shake them into a bin to count caterpillar numbers. Taking small areas from the crop, say
a quarter or a tenth of a square metre, or a number of plants equal to that found in a square metre,
is the easiest method for assessing damage levels for the entire crop.
Other crops - such as field peas, chickpeas and faba are very susceptible to damage from native
budworm from the flowering /early pod set growth stage. All sized caterpillars are attracted to any
sized pods and are able to enter pods and damage developing seed. Larger grubs are able to
devour the entire contents of the pod. These crops should be sprayed immediately after threshold
numbers of native budworm caterpillars are discovered.
Threshold spray level - the economic spray threshold levels for native budworm will vary with
crop type, grain price and control cost, for example an average of 5 - 6 caterpillars per 10 sweeps
(based on farm gate price of canola at $400 per tonne and application + chemical costs of $14/ha)
is required for canola. Specific calculations for each grower’s particular situation can be made
using a simple formula outlined in the webpage: Management and economic thresholds for native
budworm
Spray control - One well-timed spray of registered rates of synthetic pyrethroid chemical to
control native budworm should be sufficient in most situations to kill the caterpillars present.
Sweep netting of the crop should be carried out after spraying to confirm that the required level of
control has been obtained. Effectively applied synthetic pyrethroids will prevent re-infestation for
up to six weeks after spraying. Subsequent caterpillar hatchings will usually be too late to cause
any damage. Pesticide options for the control of native budworm can be found in the Winter/Spring
Insecticide Spray Chart 2014.
Wheat powdery mildew
Dan Taylor (DKT Rural) reports that powdery mildew is starting to appear on the wheat variety
Corack in crops growing south of Doodlakine. The fungal disease is currently being found at low
levels on the lower leaves within patches of the crop. One of the crops is now at the head
emergence growth stage (Z51-55) and growing on a paddock that has been in pasture for the last
two years.
Peter Eliott-Lockhart (Planfarm) reports finding powdery mildew infecting the flag leaf in a wheat
crop near Allanooka. The crop will continue to be monitored as the current warm dry weather is
supressing the disease.
Plant Pathologist Geoff Thomas (DAFWA) says that powdery mildew of wheat is favoured by mild
temperatures (15°C to 22°C) and high humidity (in excess of 70 per cent). Fluffy, white powdery
growths (becoming grey with age) of fungal spores can be seen on leaf surfaces, and under
severe pressure on stems and heads. Dense crop canopies, high nitrogen nutrition and extended
periods of canopy humidity are factors that are understood to favour mildew development. Dry
and warm weather conditions that result in periods of low canopy humidity and temperatures
above 25°C, can reduce the development of powdery mildew.
Control of powdery mildew is more difficult if infection progresses onto the head and awns and
may have an impact on grain quality. Therefore, growers are encouraged to monitor their crops,
particularly susceptible varieties, for early symptoms. Corack is rated susceptible to very
susceptible (SVS), Wyalkatchem is rated as susceptible (S), and Mace moderately susceptible to
susceptible (MSS). A well timed registered foliar fungicide can reduce the impact of this disease
but growers need to consider crop yield potential, growth stage and the weather outlook when
deciding whether to spray or not.
For further information visit the webpage Powdery mildew in cereals and refer to the disease
ratings on page 8 and 9 of the 2014 Wheat variety sowing guide for WA.
For more information visit the webpages, Registered foliar fungicides for cereals in Western
Australia (WA) and Wheat variety disease resistance ratings 2014.
Barley leaf disease
Ashton Gray (ConsultAg) reports that powdery mildew is on the increase in the susceptible barley
varieties Vlamingh and Baudin around Narrogin and Pingelly.
DAFWA Plant Pathologist Kith Jayasena commented that his spore trap studies revealed the
presence of large quantities of powdery mildew conidia in the lower great southern indicating
conditions are currently favourable for conidia release and infection of susceptible varieties. He
suggests susceptible varieties Vlamingh and Baudin need to be sprayed with new generation
triazole based fungicides and avoid repeated use of the same product in any given season to
reduce the fungal pathogen developing resistance against the registered fungicide products.
Powdery mildew damage to barley crops is often severe when infection occurs at tillering growth
stage, but when late infection occurs the yield loss will be around 20%.
Kith recommends that samples from both barley varieties to be placed in a paper bag and sent to
the address below in order to identify the strain of PM fungus and determine its response to
current fungicides.
Ashton Gray (ConsultAg) has been noticing increasing levels of net-blotch in barley crops in the
Great Southern, the disease is most evident in barley on barley rotations and with more rain
forecast for the area soon these crops will need to be closely monitored.
DAFWA Plant Pathologist Kith Jayasena commented that current barley varieties do not possess
a good level of resistance to either net type or spot type net blotch. Under high disease pressure
these two diseases can cause considerable yield loss, up to 50 per cent. He also said research
done on the south coast reveals 10% infection of spot type net blotch on the top 3 leaves can
cause around 400 kg/ha yield loss. There are many registered foliar fungicide products available
against both net blotch diseases.
Net blotch sampling is important as it allows the grains industry to be made aware of any new
incursions of the pathogen(s), changes in the net blotch fungus, and its response to fungicides and
varietal choices.
Readers are requested to send net blotch and powdery mildew infected samples to Simon
Ellwood, “The Centre for Crop and Disease Management (CCDM), Build 311 Rm 144, Curtin
University, Kent St BENTLEY 6102.
For further information visit: Managing barley leaf diseases in Western Australia, Managing net
type net blotch and spot type net blotch of barley in Western Australia and the Barley variety
sowing guide (see page 9)
For more information on the management of powdery mildew visit the webpage: Management of
barley powdery mildew in 2014 - fungicide resistance.
For a list of registered fungicides to use as foliar sprays visit: Registered foliar fungicides for
cereals in Western Australia (WA)
Oat leaf disease
Ashton Gray (ConsultAg) reports finding low levels of septoria in oat crops around Pingelly,
Narrogin and Wagin. Oat on oat rotations are the worst affected with disease evident on about 510% of the leaves on individual plants throughout the crops.
DAFWA Plant Pathologist Geoff Thomas commented that Septoria avenae blotch can be
minimised by not growing continuous oat crops or by timely applications of a registered fungicide.
For more information visit the website: Oats: leaf diseases.
For a list of registered fungicides to use as foliar sprays visit: Registered foliar fungicides for
cereals in Western Australia (WA). Attention should be given to the withholding period of the
product.
Armyworm
Peter Eliott-Lockhart (Planfarm) reports finding 14 armyworm per 10 sweeps in a wheat crop near
Allanooka, the caterpillars are currently 15mm and will be causing increasing feeding damage as
they grow larger (40mm when fully grown).
Armyworm grubs can be very unpredictable in the way they behave in crops. At times they have
been known to preferentially feed on rye grass in crops rather than damage cereals. Armyworm
caterpillars are most damaging in cereal crops (especially barley) as harvest approaches and
crops commence to dry-off. In some situations they will do a lot of damage in a short space of
time. As barley matures, parts of the stem can remain green and appetising after other parts have
dried, the grubs chew through the stem causing the heads to fall to the ground. At that susceptible
growth stage, the economic level for spraying is about 3 large armyworm grubs per square metre
of crop. Armyworms are less damaging in oats and wheat where they chew off parts of grain
heads. Spray thresholds in these crops are more like 10 grubs per m².
Assessing the numbers of armyworm in a cereal crop can be difficult, as their movements will vary
with weather conditions and feeding preference. Sometimes they are found sheltering on the
ground and under leaf litter whilst on other days they will be high up on the plants or on the heads
and easily picked up using sweepnets.
Many chemicals will control armyworm but it is essential to recognise the problem early and be
prepared to spray when economic damage is imminent, as large numbers of armyworm in barley
crops can cause a lot of damage in just a few days.
A number of effective synthetic pyrethroid insecticides are registered for the control of armyworm if
required (see the Winter/Spring Insecticide Spray Chart 2014.). However their effectiveness is
often dependent on good penetration into the crop. This can sometimes be difficult to achieve in
high-yielding thick canopy crops, especially when caterpillars are resting under leaf litter at the
base of plants. Spraying late afternoon or evening is recommended as armyworms are
predominately night feeders.
For further information visit the webpage Management of armyworm in cereal crops.
Lupin aphids
Ty Henning (TekAg) reports that aphids have formed large colonies on some plants within a
Mandelup lupin crop growing near Wongan Hills. Lupin aphids such as cowpea and blue green
aphids do not usually reach damaging levels on the lupin variety Mandelup and Ty suspected that
a lack of soil moisture causing stress to plants will have contributed to the problem.
For further information visit the webpage: Aphid control in WA lupin crops.
Cereal aphids
Cara Allan (UWA) reports that oat aphids (R. padi) have increased in numbers on cereal plots at
the WANTFA Cunderdin trial site. Some of the wheat plots have more than 50 aphids per plant on
crops that are at the head emergence growth stage (Z51 and Z52). Most aphids are currently in
dense clusters on the lower leaf blades, close to the leaf sheath that surrounds the stems. Peeling
back the leaves from the stem is often needed to find the aphids. With warmer weather aphids are
likely to rapidly increase in numbers unless they are slowed down by aphid predators, parasitoids
or aphid diseases.
Ashton Gray (ConsultAg) reports finding low levels of cereal aphids in some cereal crops around
Yealering, Narrogin and Cuballing.
More information on control of cereal aphids can be found in PestFax No.14 15 August 14, GRDC
cereal aphid factsheet, GRDC Beneficial Insects: back pocket guide and at the DAFWA webpage:
Aphid feeding damage to cereal crops and the Winter/Spring Insecticide Spray Chart 2014.
Canola aphids
David Cameron (Farmanco) reports finding turnip and green peach aphids in canola crops in the
Moora region. The turnip aphids are infecting the flowering spikes while the green peach aphids
are being found on the leaves on the lower two thirds of the plants. The aphid numbers are being
monitored and if populations continue to increase control measure will be taken.
Monica Field (Farm and General) found turnip and cabbage aphid populations in canola crops
increased during the last week in areas around Grass Patch and the Esperance Mallee region.
Population levels in some crops are now at or above threshold levels resulting insecticide control
sprays being applied.
For further information visit: PestFax No.14 15 August 14, Aphid management in canola crops and
the Winter/Spring Insecticide Spray Chart 2014.
Blue oat mites
Cara Allan (UWA) reports that blue oat mites (BOM) are causing silvering and premature yellowing
of lover leaves on cereal plots at the WANTFA Cunderdin trial site. In some plots BOM numbers
are in excess of 30 mites per plant. The plots have not received an insecticide spray this season
and the mites have continued to breed and multiply. Mites often reach their peak numbers
(usually the third generation) during spring. Although their numbers can be high it is unlikely that
spray control is economically justified at this time of the year. Use of insecticide will be more
effective if applied prior to or at the time of seeding emergence to carry-over populations of mites
into the following Autumn.
More information can be found in the DAFWA webpage: Diagnosing blue mites in grain crops
Mice
Monica Field (Farm and General) reports that mice have started to cause low levels of damage to
canola pods on two properties west of Grass Patch. Some paddocks on these properties were
baited early in the season to control mice numbers. The current damage is occurring in areas
where mice numbers weren’t a problem earlier in the season.
For further information visit the GRDC webpage: Mouse management
Also available:
List of registered insecticides
A list of registered insecticides to control winter/spring pests on canola, lupins, cereals, field peas
and pastures is available on the PestFax webpage: Winter/Spring Insecticide Spray Chart 2014
A list of registered insecticides to control autumn/winter pests on canola, lupins and cereals is
available on the PestFax webpage: Autumn Winter Insecticide Guide 2014
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 DAFWA offices for a cost
of $10.00 or by mail order by phoning the DAFWA South Perth office on +61 (0)8 9368 3710.
Free insect identification
Having troubles identifying mites or other pests? For free identification, send your digital pictures
(in focus) or live specimens (in a non-crushable plastic jar) to Peter Mangano or Svetlana Micic at
the postal details below.
Svet Micic, DAFWA Albany
444 Albany Highway,
Albany WA 6330
Email: svetlana.micic@agric.wa.gov.au
Phone: +61 (0)8 9892 8591 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 3753 or +61 (0)404 819 534
Integrated Pest Management Guidelines for grains
AgTactics and AgMemo
Other regional DAFWA news updates are available on DAFWA website.
Seasonal climate outlook
Seasonal climate outlooks are available on DAFWA website.
AGWEST Plant Labs
Plant disease diagnostic services are 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 the
DAFWA website or the AGWEST Plant Laboratories
Next issue of PestFax – 05 September 2014
Important disclaimer
The Chief Executive Officer of the Department of Agriculture and Food and the State of Western
Australia accept no liability whatsoever by reason of negligence or otherwise arising from the use
or release of this information or any part of it.
Copyright © Western Australian Agriculture Authority, 2014