Issue Number: 08
Date: 04/07/2014
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
Sclerotinia in canola
Aphids
Caterpillars
Slugs
Earwigs in canola
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.
Mites and lucerne flea
Courtney Piesse (Elders) reports that a four to five leaf canola crop near Cranbrook, has been
damaged by redlegged earth mite (RLEM) at a stage when the crop would normally have been
expected to be safe from mite damage. The damage is especially evident in areas of the paddock
where the canola has been damaged by herbicide. The canola was sown into last year’s pasture
and did not receive any pre-emergent miticide control. Last year’s pasture paddocks are most
likely to have the highest populations of RLEM especially those that were not heavily grazed and
did not have a spring insecticide spray. If RLEM numbers are high following a pasture rotation they
are capable of damaging the more advanced four to six leaf canola plants.
A farmer at South Stirling reports that a canola crop at the three leaf stage was damaged by
RLEM, despite the paddock receiving a spray of bifenthrin pre-seeding. A few years ago a
paddock about one kilometre away tested positive for synthetic pyrethroid (SP) resistant RLEM. It
is highly probable that this current paddock also has RLEM that are resistant to SP’s.
Courtney Piesse (Elders) reports that lucerne flea are damaging a four leaf wheat crop near
Frankland. A recent dry spell has slowed crop growth which is struggling to outgrow the feeding
damage and a spray is likely to be required. Lucerne flea has also been reported damaging cereal
crops in the Ravensthorpe area. The pests have now been controlled by using registered rates of
organophosphate sprays.
Courtney also has observed what appears to be brown wheat mite on cereals in the Cranbrook
area. The brown wheat mite (Petrobia latens) has a very similar appearance to bryobia mites with
long forelegs and a lighter coloured, brownish body. They are often mistaken in identity for
bryobia or other mites, however they rarely cause economic damage to cereals at this time of
year. Cooler winter temperatures and more frequent rainfall will see these mites decrease in
numbers and they are unlikely to cause further damage to crops unless extended dry and sunny
periods prevail.
Redlegged earth mite control failure
The Department of Agriculture and Food, Western Australia (DAFWA) provides a free RLEM
resistance testing service. Growers and agronomists who observe surviving RLEM following
applications of insecticides such as bifenthrin or alphacypermethrin should take advantage of this
service to determine the resistance status of their mites. To use this free service contact –
Svet Micic, DAFWA Albany
Email: svetlana.micic@agric.wa.gov.au
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
Sclerotinia in canola
DAFWA Plant Pathologist Ciara Beard visited a property near Northampton yesterday where a
grower found apothecia in his canola paddock. These are the small cream coloured mushrooms
that spread sclerotinia spores. The apothecia found this week were tiny so it is likely they are
newly germinated following recent rain. They were found in a
canola crop that is at 20%-30% flowering, and the grower is
intending to apply fungicide to the crop this week. Crop
flowering stage, along with weather conditions are the main
determinants of when to spray for sclerotinia. DAFWA
research has shown the optimal time for a single fungicide
application in most years is 20 - 30% flowering (when 15 - 20
flowers are open on the main stem).
DAFWA Plant Pathologist Kith Jayasena also reports seeing
apothecia of sclerotinia near the DAFWA office in Albany.
This indicates that conditions may be right for emergence of
apothecia more broadly across the high rainfall grain belt.
For more information on the sclerotinia lifecycle, disease
symptoms and management strategies with fungicide see
Pest Fax No.7 27 June 14 and the DAFWA webpage
Managing sclerotinia stem rot in canola.
Figure 1 Sclerotinia apothecia
Aphids
Daniel Bell (Landmark) has observed high numbers of turnip aphids on wild radish in pasture
paddocks east of Esperance. The feeding damage from the aphids is killing the plants.
DAFWA Entomologist Svet Micic says that cool wet conditions during winter often keep aphid
numbers below damaging levels. Mild and warmer weather patterns through winter are likely to
favour aphid survival and increase through winter. Turnip and cabbage aphids are nearly always
present on canola crops each spring. Rising spring temperatures will see a build-up in aphid
populations, but in many years they never reach economically damaging levels. Early monitoring
of crops will give advance warning of aphid increase. Use of preventative sprays is often
unnecessary and only lead to death of beneficial insects and increase in the likelihood of selection
pressure to select for aphids that are resistant to insecticides
For further information see the Diagnosing canola aphid and Aphid management in canola crops
webpages
Caterpillars
Woolly bear caterpillars
A grower in the Dongara area reported to PestFax that some of their paddocks are “crawling” with
high numbers of woolly bear caterpillars. The caterpillars are being seen in hundreds per square
metre on pasture/weedy paddocks and in some cases even climbing the walls of nearby houses.
The presence of woolly bear caterpillars has been reported to PestFax over the past two weeks
mainly from areas north of Geraldton, although the caterpillars are also being found over
widespread areas including the Perth metro area. Some crop damage has occurred from the
movement of caterpillar into crops from adjoining weedy edges or pastures.
For further information see the caterpillar section in PestFax No.6, 20 June 2014.
Pasture day moths
DAFWA Entomologist David Cousins has observed pasture day moth caterpillars in moderate
numbers in pasture paddocks near Badgingarra and lesser numbers near Dongara and further
south at Williams. The colourful day flying moths with brown and yellow patterns on their wings
can be seen flying on some paddocks. Courtney Piesse (Elders) reports that pasture day moth
caterpillars have caused chewing damage to a three leaf wheat crop in the Williams area. These
caterpillars usually feed on broadleaved weeds, however when these weeds are removed by
herbicide sprays the caterpillars are known to move onto cereal crops.
Pasture day moth caterpillars (Crop insects: the ute guide page 33) are dark brown with yellow
and reddish orange markings. They have two prominent yellow spots near the end of the body
and an orange-black head. The moths have brown and yellow patterns on their wings and may be
seen flying by day (as the name implies).
Pasture day moth larvae rarely cause economic damage to pastures or crops. They have a
preference to feed on broad-leafed weeds such as capeweed, in some paddock situations this
feeding preference is considered beneficial. The caterpillars grow to about 60 mm long before
commencing to burrow into the ground where they pupate. The insect has only one generation per
year.
For further information and images see the pasture day moth info sheet
Slugs
Daniel Bell (Landmark) has found black keeled slugs in a cereal paddock near Ravensthorpe.
The cereal crop which is at the two to five leaf stage is out growing any damage. A farmer in the
Katanning region reports that his crop is now outgrowing slug damage from black keeled slugs as
well as reticulated slugs. However, the slugs were present in paddocks that had no previous
known history of the pests. Black keeled slugs can survive a hot dry summer and one to two slugs
per square metre can cause significant damage to a germinating canola crop.
Further reports of slugs damaging crops have been received from Mt Barker, Katanning,
Kojonup and Boyup Brook.
For further information on slug control refer to Identification and control of pest slugs and snails for
broadacre crops in WA and the GRDC publication Slug control: Slug identification and
management. Visit the South Australian Research and Development Institute (SARDI) website to
view information on slug baiting.
Earwigs in canola
Courtney Piesse (Elders) reports that a farmer near Kendenup has seen chewing damage to a
four to five leaf canola crop. The farmer had inspected the crop but could find no insect pests in
the area of the damage. Courtney advised the farmer to place a pitfall trap on the edge of the
damage and to check it the next day. Earwigs and weevils were found. Native earwigs do not
cause crop damage whereas european earwigs can cause significant crop damage and can be
difficult to control. The farmer intends to get the earwigs correctly identified before implementing
any control measures.
Correctly identifying the pest responsible for crop damage is important in choosing the right control
measure as it avoids the application of unnecessary or incorrect insecticide sprays.
For more information on identifying European earwig refer to the DAFWA webpages Management of European earwig and Diagnosing European earwig
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 Departmental 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? 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 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
AgTactic and AgMemo
Other regional DAFWA news updates are available on DAFWA website.
Growing Season Outlook
Seasonal climate outlooks are available on DAFWA website.
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 the
DAFWA website or the AgWest plant laboratories webpage.
Next issue of PestFax – 11 July 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.