Issue number: 22
Date: 10/10/2014
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
Fusarium crown rot
Native budworm
Bean yellow mosaic virus and black pod syndrome in lupin
Armyworm
Powdery mildew on barley
MyPestGuide identification and reporting tool available now
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.
Fusarium crown rot
DAFWA has received reports of fusarium crown rot affecting between 30-50% of wheat paddocks
from around Merredin. DAFWA research officer Shahajahan Miyan also reports high levels of
crown rot at Salmon Gums. These reports are consistent with a constant demand on the
Department of Agriculture and Food’s diagnostic service, Agwest Plant Laboratories, to identify
root and crown diseases in samples from the central and southern agricultural region.
DAFWA Plant Pathologist, Daniel Hüberli, says that the lead up to harvest is an important time to
monitor crops and identify these diseases to assist planning to minimise their impact for next year.
Daniel says that the increased disease expression this year is likely the result of intensive cereal
production, in combination with 2013 and 2014 seasonal factors. In 2013 wet spring conditions
probably contributed to disease build-up but with few white heads seen due to the soft finish. In
Supporting your success
2014, the drier spring in many areas has resulted in a high expression of white head formation.
Crop rotation to non-cereals is the key to management of paddocks that have high levels of crown
rot as there are no fungicides registered to address crown rot. A break from cereals of at least two
years may allow breakdown of infected cereal stubbles in which the pathogen survives. So
paddock management decisions based on this year’s observations will be critical to next year’s
cropping program. Daniel says that there is no single strategy to minimise the impact of soil-borne
diseases so integrated paddock management was essential. He suggests that if growers are at a
high risk of crown rot for their 2015 crop, they may choose to sow a break crop or in less severe
infestations sow a less susceptible cereal using inter-row sowing, however, variety options are
limited.
Crown rot predominantly affects wheat and barley, and to a lesser extent oats. It is caused by
Fusarium, a soil-borne fungus, infecting plants at the crown and reducing water supply to the
stem. Affected plants show white head formation and failure to fill grain in a season where
moisture is limiting at the end of the season.
White head formation (Figure 1) does not always occur and is not unique to crown rot.
Confirmation of crown rot infection is diagnosed by looking for the distinctive honey-brown
discolouration of the stem base or lower node (Figure 2), when leaf sheaths are removed. Direct
signs of the fungus may also be present as pink or purple colouration.
Figure 1 A white head affected by crown rot next to a normal grain head
Figure 2 Crown infection with honey brown discolouration at the stem base
Figure 3 In severe cases white heads develop after flowering and these can occur across entire paddocks
Growers with paddocks containing white heads or other patchy, poor growth (Figure 3) are
advised to check for the presence of the disease and confirm suspected infections by taking plant
samples now or a soil sample after harvest. Samples can be despatched to the AGWEST Plant
Laboratories to confirm what soil-borne disease they may be dealing with.
With the support of the Grains Research and Development Corporation, DAFWA has established
research to assess management options and test commonly grown wheat and barley varieties for
susceptibility to crown rot.
For further information on disease management see MyCrop for crown rot of cereals and for
testing services AGWEST Plant Laboratories.
Native budworm
A budworm moth trapper near Kojonup has seen moths numbers increase from zero four weeks
ago to the 195 captured this week. The farmer commented that the early sown canola crops are at
least two weeks away from swathing.
Cuballing Narrogin and Pingrup have also seen notable numbers of moths trapped over recent
weeks. See Native Budworm Moth Trap Numbers 2014.
Many crops in northern and eastern cropping areas are now being harvested or have been
swathed and are unlikely to be vulnerable to damage from any remaining native budworm grubs.
Crops in south western high rainfall locations (especially late sown crops) may still be vulnerable
to damage and these crops will need to be checked, using a sweep net at several locations in the
crop, to determine if numbers are below spray threshold levels
Farmers with caterpillars in their crops need to be mindful of insecticide withholding periods (WHP)
close to harvest and remember that windrowing is classified as harvest.
For information on insecticide withholding periods refer to PestFax Issue 20 26/09/2014 For
information on native budworm reports see PestFax map and previous issues of PestFax Issue
21, PestFax issue 20, and PestFax issue 19.
For further information on native budworm visit the webpage: Management and economic
thresholds for native budworm.
Pesticide options for the control of native budworm can be found in the Winter/Spring Insecticide
Spray Chart 2014.
Bean yellow mosaic virus and black pod syndrome in lupin
Karrie Stratford (Landmark) reports finding a Mandelup lupin crop east of York of with blackened
pods (Figure 4) and stem streaking on random plants evenly distributed throughout the crop.
Volunteer clover is present under the whole crop. The paddock has been in crop for the last 7
years, with the last lupin crop thought to have been 7 years ago.
Figure 1 Black pod syndrome symptomatic Mandelup lupin from east of York: Photo Karrie Stratford
Landmark
DAFWA plant virologist Monica Kehoe says that when narrow-leafed lupin plants are infected late
in the season with bean yellow mosaic virus (BYMV) (i.e. after flowering when pods are forming)
the symptoms are necrotic stem streaking, along with black and flattened pods which produce very
few or no seeds. It is commonly called black pod syndrome (BPS). The most common source of
BYMV for lupin crops is volunteer clover species within and around crops. Mandelup is highly
susceptible to BPS.
The management of BPS is best implemented through already established integrated disease
management recommendations for BYMV. Given that the time of infection is critical for BPS,
emphasis should be placed on maximising volunteer clover control within the lupin crop. It is also
important to avoid planting next to or downwind of legume pastures and other narrow-leafed lupin
crops as they can be sources of BYMV. While the virus is transmitted by aphid species that
colonise lupins, insecticides are ineffective at controlling BYMV. For further information visit the
webpage Bean yellow mosaic virus in lupins.
Armyworm
Phil Barrett-Lennard (agVivo) reports that ryegrass heads at his north Gingin property have been
severely damaged by insect chewing. In at least two paddocks on his property the ryegrass heads
have been chewed removing much of the flowering heads / developing seeds and leaving only the
skeletonized stem. Chewing damage was also found on triticale growing in one of the paddocks in
a mixture with clover and ryegrass. Lopped heads or chewing of the triticale heads could be seen
on a few plants.
Phil initially struggled to find the caterpillars, which often hide by day and feed at night, but shifting
through the leaf litter at the base of the pasture sword revealed the hiding caterpillars. In another
paddock being mown for hay lots of armyworm caterpillars could be seen when they were pickedup by the cutter bar. A neighbouring farmer estimates he has hundreds of armyworm per square
metre on some of his paddocks with large flocks of Ibis birds flying in to take advantage of the
feast.
A large amount of caterpillar faeces (like mini hay bales) on the ground near damaged plants
could be seen in some paddock areas, this is a typical sign of armyworm activity.
The caterpillars are plump and smooth (hairless) and may be distinguished by longitudinal stipes
especially the three parallel white stripes on the collar just behind their largish head. Phil notes
that their sizes ranged from 15mm to 40mm long.
Andrew Heinrich (Farm and General) reports that armyworm caterpillars have been detected in a
barley crop west of Esperance (Dalyup). The caterpillars range in size from 15-20 mm in length
and are currently feeding on the last of the green leaves as the crop matures. The barley heads
are not being damaged as yet and it is hoped that swathing in the next few days will hasten the
crop drying off and lessen the potential pest damage.
Like many other insect pests armyworm are quite sporadic in their occurrence and population
levels can vary dramatically between locations and seasons. There are four main species of
armyworms that will attack cereals and grasses in the Western Australian grainbelt, with the
common armyworm (Leucania convecta) and Inland armyworm (Perectania dyscrita) most often
associated with major outbreaks.
Occasionally armyworm moths move in large flights in search of food but more often it seems they
breed within the same paddock or local area. In winter it may take several months for eggs to
develop to adult moths, but this will shorten to about six weeks with warm spring temperatures.
Armyworm caterpillars are most damaging in barley crops close to harvest. As barley matures part
of the stem usually remains 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. Armyworm
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.
For further information see the webpages Diagnosing armyworm and Management of armyworm
in cereal crops.
Powdery mildew on barley
There have been reports of powdery mildew on flowering Baudin barley near Kojonup. The crop
had the label rate of Cogito® (propiconazole and tebuconazole) applied four weeks previously.
For further detailed information on powdery mildew on barley see PestFax No.9 11 July14 and
visit the webpages: Management of barley powdery mildew in 2014 and fungicide resistance and
Barley Variety Sowing Guide (see P.9).
Curtin University are always looking for samples for pathotype and fungicide resistance analysis.
Growers can submit their 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.
MyPestGuide identification and reporting tool available now.
MyPestGuide is a pest identification guide to allow users to quickly search for and identify almost
200 crop pests, beneficial and biological control agents along with grain storage pests and
biosecurity pest threats specific to Western Australia. Pests can be searched for based on the
crop it was found in, damage observed and its type or size.
A key function is that users can send pest reports direct to DAFWA with a photograph, GPS
coordinates and other details. DAFWA's expert responses are synchronised back to the user's
device in the field. There is a requirement for a more coordinated approach to industry biosecurity
and a need to engage growers, agronomists and members of the community in general plant pest
surveillance activities.
The reporting function in the MyPestGuide app is one way for the local community to help collect
this evidence and strengthen agricultural industries. MyPestGuide is available for Android devices
from the Google Play Store and for iPhone/iPad from the Apple iTunes Store. Click the links or
search for ‘mypestguide’.
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 is now a FREE mobile app & reporting tool!
The original crop insects ute guide which covers crop pests, beneficial insects, biological control,
grain storage pests and biosecurity pest threats specific to WA has now been made into a FREE
mobile phone app and pest reporting tool called MyPestGuide available for Android devices from
Google Play Store and for iPhone/iPad from the Apple iTunes Store , click the links or search for
“mypestguide”. Hardcopy ute guides are still available by phoning the DAFWA South Perth office
on +61 (0)8 9368 3710 ($10.00 each).
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 – 17 October 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