Issue Number: 12
Date: 01/08/2014
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
Canola sclerotinia
Wheat powdery mildew
Lupin anthracnose
Barley leaf rust
Barley covered smut
Native budworm moths
Diamondback moths
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.
Canola sclerotinia
Erin Cahill (Agvivo) reports seeing low to moderate levels of sclerotinia in canola crops around
Jurien, Badgingarra, Dandaragan, Moora, Walebing and west of Wongan Hills. Erin also
commented that very few or no apothecia could be found in this year’s canola crops. But in the
nearby cereal crops that had been sown into last year’s canola stubble there were significant
numbers of apothecia, particularly in areas where sclerotinia was noticeable last year. Some
farmers commenced spraying with Prosaro ™about 2 weeks ago to control the disease and it is
likely many more crops in these areas will be sprayed in the coming weeks if the disease levels
continue to be a problem.
Rick Horbury (Bayer Crop Science) also reports that disease is now kicking off around
Badgingarra, Moora and Bolgart with early stem infection observed.
Canola Pathologist Ravjit Khangura says that early stem infection can be recognised by white
fluffy growth of the fungus on the main stem or at the branch or leaf axils. Early lesions on the
stem are usually small, oval and sometimes may appear in the form of concentric rings. Further
progression of stem lesions will be mostly be driven by moist and humid conditions. Under
prolonged wet conditions and high humidity, lesions rapidly expand and completely girdle the
stem, causing the infected stem to break-off and lodge at the point of initial infection. Heavy
infection on the main stem before pod fill results in substantial yield
loss.
This season has seen early flowering overlapped with weather
conditions favourable for infection and disease development.
Canola that was sown in paddocks with a history of sclerotinia and /
or in close proximity to last year’s sclerotinia affected canola or lupin
paddocks are at high risk.
Fungicide application is the only option for in-crop management of
sclerotinia. Spraying is recommended between 20-50% flowering
and before the symptoms develop, as fungicides have no curative
activity once the disease is established. The benefits of late
spraying are unknown and Ravjit suggested that if growers decide
to apply fungicide after finding early stem infection (yet within the
flowering spraying window), it may be worthwhile leaving a couple
of strips unsprayed to compare the disease levels and determine the
economic advantage of late fungicide application. Growers also
need to check product label to ensure compliance with withholding
periods. Currently, registered fungicides for management of
Sclerotinia in canola include Prosaro®, Iprodione eg. Rovral Liquid®
and Procymidone eg. Sumislex®and Fortress®.
Figure 1. Early Sclerotinia
infection on the main stem
indicated by white fluffy fungal
growth.
For more information on the sclerotinia lifecycle, disease symptoms and management strategies
see the DAFWA webpage Managing sclerotinia stem rot in canola.
Wheat powdery mildew
Richard Marsland (Farm Manager) reports finding powdery mildew infection on crops of
Wyalkatchem wheat west of Mingenew. The infection is currently in the lower canopy of the crop
which is approaching full flag emergence. Decisions on the potential use of fungicide will be
delayed until the flag is fully emerged.
Plant Pathologist Ciara Beard (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). Dense crop canopies,
high nitrogen nutrition and extended periods of canopy humidity are factors that are understood to
be favourable for mildew development. Dry and warm weather conditions that result in periods of
low canopy humidity can reduce the development of powdery mildew.
The biggest influence on occurrence of the disease is likely to be the susceptibility of the variety.
Wyalkatchem is rated as susceptible (S), Corack susceptible to very susceptible (SVS) and Mace
moderately susceptible to susceptible (MSS).
Ciara says that in some historical trials carried out by DAFWA in the Northern Agricultural area
yield losses of 10-15% have been recorded in badly affected crops. Control of powdery mildew is
more difficult in advanced stages of epidemic development so growers are encouraged to monitor
their crops, particularly susceptible varieties, for early symptoms. If mildew infection progresses
onto the head and awns it can be difficult to control and may have impact on grain quality. When
weather conditions are favourable for continued disease development, well timed foliar fungicides
can reduce the impact of this disease.
For further information see the DAFWA webpage powdery mildew in cereals and the varietal
disease ratings on P.8 and 9 of the 2014 wheat variety sowing guide of WA.
Lupin anthracnose
Chris Pinkney and Craig Topham (Agrarian Management) reported finding low levels of
anthracnose occurring in Amira albus lupin crops in the Northern Agricultural area. Incidence of
infection is currently at low levels, however infected plants can be clearly identified within the
crops, which are mostly at flowering to early podding stage. Weather conditions in the district have
been relatively favourable for disease development so far this year.
Plant Pathologist Geoff Thomas says that Anthracnose is a fungal disease spread by rain-splash
of spores from infected plants. Anthracnose is favoured by wet conditions and therefore the
greatest risk of disease is in high-medium rainfall areas, particularly the northern agricultural
region where blue lupins are abundant. A period of drier weather should delay the spread of
disease.
The disease can affect stems, flowers and pods causing bending and twisting of the infected
tissue with associated pink-orange spore masses within the lesion. Anthracnose infection on pods
can result in pod abortion, yield loss and poor seed quality (caused by grain discolouration in
severe situations).
The lupin variety Amira rated as moderately resistant (MR) to Anthracnose has substantially
improved resistance compared with Andromeda (MS) and Kiev Mutant (VS) but can still suffer
infection, including on pods.
In high disease situations, foliar fungicide sprays applied at early podding on main stems and
again on first order branches (if required) reduced yield loss in previous trials conducted on
narrow-leafed lupins. The anthracnose disease needs rain to actively spread therefore application
of fungicide as a protectant prior to a significant rain event (spore spread) is most effective.
Currently the only fungicides registered for foliar application on lupins are those containing
Mancozeb.
For further information see the DAFWA webpage Lupin foliar diseases: diagnoses and
management.
Barley leaf rust
Quenten Knight (Precision Agronomics Australia) reports finding barley leaf rust in Baudin barley
crop near Wittenoom Hills, the barley leaf rust pustules can be quite easily seen within the crop.
The barley, which is currently being grazed by sheep, will be sprayed with prosaro® fungicide late
this week when the sheep have been removed. Quenten also noticed reasonable levels of
powdery mildew present in the same crop.
Plant Pathologist Kith Jayasena says leaf rust is a difficult disease to manage when established.
Where leaf rust is found in very susceptible barley crops, such as Baudin, he advises growers to
consider spraying their crops with a registered foliar fungicide product. When selecting fungicide
options growers should consider what other diseases are present in the crop and choose the
product accordingly.
Kith said, the growers in the Wittenoom Hills area should check there susceptible to moderately
susceptible crops regularly for presence of leaf rust and take appropriate control measures. Wet
leaves, high canopy humidity and warm weather are conducive to leaf rust infection.
For more information visit the following webpages: Barley leaf rust, Managing barley leaf diseases
in Western Australia and Barley Variety Sowing Guide (see P.9)
For a list of registered fungicides to use as foliar sprays visit the webpage: Registered foliar
fungicides for cereals in Western Australia (WA)
Barley covered smut
Matt Willis (Elders) reported sighting covered smut on a crop of Hindmarsh barley south of
Wyalkatchem. The crop was sown using Tebuconazole fungicide (Raxil T®) fungicide treated
seed, which is registered for the control of barley smut diseases.
Joe Delaney (Elders) reports that smut infection is being seen on early heading crops of
Hindmarsh and Scope barley in the Dalwallinu area. In one case the crop was sown without an
effective seed dressing.
Plant Pathologist Geoff Thomas says Hindmarsh barley is very susceptible for covered smut
disease. The covered smut is seed-borne (externally) and also soil borne. The germinating
spores will infect the seedling before the seedling emergence. The infected heads mostly emerge
late compare to healthy heads and may also be trapped in the boot of the flag leaf sheath. The
covered smut spores are release at harvest time and thereby contaminate uninfected seed,
harvesting machinery and soil. The presence of smut in the grain can lead to downgrade the
quality and exclude barley from delivery. Geoff said disease can be managed by regular
application of seed dressing fungicide, selecting resistance varieties, using uncontaminated seeds
and paddock rotation.
There are a number of different smut diseases of cereals and their identification is important for
effective management for further information see the DAFWA webpage Smut and bunt diseases,
identification and management and Seed dressings and in-furrow fungicides for cereals in WA
2014
Native budworm moths
Rob Alderman (Landmark) reports finding native budworm caterpillars in a canola crop near Port
Gregory. Rob used an insect sweep net to monitor the crop and found diamondback moth larvae
(see article below) along with the budworm. The native budworm caterpillars are currently
immature, less than 10 mm long, and their numbers averaged 4 caterpillars per 10 sweeps.
Volunteer farmers and some DAFWA staff have commenced weekly pheromone trapping for
native budworm moths in the past week as part of a yearly program to monitor the potential risk of
native budworm caterpillars to pulse and canola crops. This week’s results indicate that flights of
native budworm moths have commenced in some areas of the wheat belt, with catches in the past
week from Eradu (306 moths) Cowcowing (68), North Cuballing (5), Greenough (35)
Kellerberrin (98), Maya (13), Merredin (3), Mollerin (23), Wubin (20), and Wyalkatchem (4).
DAFWA technical officer Joanne Walker sweep netted two lupin crops this week and found 1
caterpillar per 10 sweeps (5-10mm) at Eradu and 1 caterpillar per 10 sweeps (0-5mm) at
Greenough.
For further information on native budworm see the Management of Native Budworm Farmnote.
Diamondback moths
Rob Alderman (Landmark) reports finding diamondback moth (DBM) caterpillars in a canola crop
near Port Gregory. Using an insect sweep net to check several locations within the crop Rob
found most sites had between 5-10 caterpillars per 10 sweeps and numbers rising to 80-90
caterpillars in one less healthy, stressed part of the crop. The advanced canola crop is at about
the 80% flowering / pod formations growth stage and has good yield potential. The crop will be
closely monitored over coming days to determine if the DBM caterpillar populations continue to
increase, remain static or decline.
Numbers of 100 DBM or more per 10 sweeps are required before spraying is justified in late
flowering crops that have adequate soil moisture.
Some helpful considerations are
•
•
A high proportion of small grubs (less than 3 mm) in a sample often indicates that numbers
will increase further.
Regular assessments of the number of grubs in the crop are required because the numbers
can fluctuate and are just as likely to decrease as they are to increase at any stage
throughout the growing season.
When checking crops with a sweep net it is good to be mindful that small native budworm grubs
can easily be confused with DBM grubs in canola crops. DBM grubs are usually pale yellowish
green and tapered at each end of their body, which grows to about 10mm long. They often
wriggle rapidly when disturbed and will hang on a silken thread. Native budworm grubs are far
more damaging as they grow to larger sizes (up to 40mm long) and will chew into the pods.
For further information visit the webpages: Diagnosing diamondback moth and the GRDC
diamondback moth factsheet.
Also available:
List of registered insecticides
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 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
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 webpage.
Next issue of PestFax – 08 August 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