Aphid activity update
Canola and lupin aphids
- Canola aphid locations: Ogilvie to Esperance.
- Lupin aphids: Dandaragan
There have been widespread reports of cabbage aphid infestations in canola crops at Yarragadee, Yandanooka, Mingenew, West Morawa, Bodallin, Wongan Hills, Cunderdin, Meckering, Tammin and Howick. These crops were moisture stressed.
Turnip aphids have been found in moisture stressed canola crops near Bodallin and canola near Howick. Agworld users have also reported turnip aphids in canola near Wongan Hills.
Cabbage and turnip aphids can cause significant yield loss to canola in spring, especially in areas where plants are already moisture stressed and aborting flowers or pods given the plants limitations. Aphid infestations in moisture-stressed canola crops that are in the fully podded stage, can result in lower seed production or development of shriveled seed due to aphids preventing seed fill.
Research Scientist Andrew Philips (DPIRD) has observed green peach aphids (GPA) on canola near Moonyoonooka. The affected crop had been sprayed a few days prior with chlorpyrifos and alphacypermethrin. Agworld users have also reported finding GPA in canola near Geraldton.
GPA typically do not pose a significant late-season threat unless they congregate in thick clusters on pods.
Chris Wilkins (Vision Agribusiness Services) reports finding high numbers of GPA causing stress to branch terminals in a lupin crop at Dandaragan. Many of the aphids were turning orange, which is a common occurrence in green peach aphids, especially when they are infected with an aphid fungus. The aphid clusters were causing further stress to an already moisture-stressed crop.
To read about prior canola aphid activity this season refer to DPIRD’s 2023 PestFacts WA Issue 14 article cabbage aphids have been increasing in canola and Issue 10 turnip yellows virus detected in flying green peach aphids and in canola.
For more information on canola aphids refer to:
- DPIRD’s aphid management in canola crops page
- DPIRD’s diagnosing canola aphids page
- DPIRD’s 2017 Protecting WA Crops Issue 3 newsletter Aphids – WA’s insect problem children
- GRDC’s aphids in your crops YouTube video.
Cereal aphids
- Cunderdin
- Meckering
- Tammin
- Pingelly
Dan Taylor (DKT Rural Agencies) reports finding oat aphids in barley and wheat crops at Cunderin, Meckering and Tammin. The infested crops were moisture stressed.
Harmohinder Dhammu (DPIRD) recently found high numbers of oat aphids in a wheat trial site at Pingelly, with many tillers having more than 60 aphids.
Growers are advised to inspect their cereal crops for aphids, especially along crop edges where they tend to colonise first and form hotspots.
For more information on cereal aphids, and previously reported cereal aphid activity this season, refer to DPIRD’s diagnosing cereal aphids page and 2023 PestFacts WA Issue 10 article russian wheat aphid.
Management
Seasonal conditions have been conducive to aphid numbers to build up and cause significant stress to already stressed plants. This can seriously reduce yields.
Remember that naturally occurring parasitoids and predators such as hoverflies, wasps, lacewings and ladybird beetles will also increase with warming weather. These predators can keep aphid populations below threshold levels, and unnecessary spraying of 'anti-feed' synthetic pyrethroid sprays will only counteract their benefits. When spraying, consider spray options that are soft (for example pirimicarb) on predators. Growers need to check canola crops for fungal infections and parasitism in aphids before deciding whether to invest in an insecticide spray. For more information, refer to the department’s know what beneficials look like in your crop and Cesar Australia’s beneficial’s chemical toxicity table page.
If more than 20% of canola plants are infested with colonies of cabbage or turnip aphids, control measures should be considered to avoid yield losses. The risk of economic yield losses to aphids is increased if canola crops are already under some degree of moisture stress or experiencing poor finishing rains. If spraying is required, a border spray may suffice for cabbage aphids, which are most commonly found within 20 to 30 metres of the crop edge.
Barley crops are most at risk from corn and oat aphids. This is due to the possibility of downgrading from malt to feed quality, as aphid feeding damage can cause grain shrivelling. If 50% of tillers have 15 or more aphids, then the feeding damage may cause reductions in yields by up to 10%. It may also reduce grain size. Yield loss is greater in crops that had aphid colonisation from early tillering. Russian wheat aphid (RWA) thresholds are dependent on the crop stage, the time until head emergence, predicted yield and cost of spraying. A RWA threshold calculator is available on GRDC’s russian wheat aphid page.
For a list of insecticides registered for use on aphids, see DPIRD’s 2023 winter spring insecticide guide.
More information
For more information contact research scientists Svetlana Micic in Albany on +61 (0)8 9892 8591 or Dusty Severtson in Northam on +61 (0)8 9690 2160.
Article authors: Cindy Webster (DPIRD Narrogin) and Dusty Severtson (DPIRD Northam).
Diamondback moth numbers remain low
- Mingenew
- Mukinbudin
- Merredin
- Kellerberrin
- Howick
Diamondback moth (DBM) caterpillars and moths are continuing to remain in low numbers late into the season across all grainbelt areas.
Widespread surveillance for DBM in canola focus crops is being conducted until the end of the season as part of a Grains Research and Development Corporation (GRDC) funded project on DBM surveillance.
DBM caterpillar numbers are currently well below threshold, although many crops are experiencing moisture stress. Growers are urged to monitor canola crops for DBM and native budworm caterpillars.
Dave Nicholson (DPIRD) found 3to 10 caterpillars per 10 sweeps in podding canola at Dandanning (Mukinbudin).
Rachael Minett (Primaries CRT) found less than one caterpillar per 10 sweeps in early flowering canola at North Howick.
Mingenew Irwin Group (MIG) found an average ranging from 0 to 2 caterpillars per 10 sweeps in five canola focus crops in the Mingenew area.
An average of less than one caterpillar per 10 sweeps was found at the following DBM surveillance sites in the last fortnight: Merredin, Kellerberrin and Mukinbudin. No caterpillars were recorded at Geraldton, York, Corrigin, Kondinin, Narembeen, Albany, Esperance, Dandaragan, Wickepin, Kalannie and East Wubin.
Moth trapping update
- Usual trapping locations
The number of moths captured in pheromone-baited traps over the last fortnight were highest at: Nolba (67 moths), Marrah (59), Dandanning (56), Yallabathara (44), Kondinin (36), Perillup (31), Dandaragan (31), East Wubin (26), Moonyoonooka (25), Daadenning Creek (Kellerberrin) (25), Kalannie (20), Wicherina (16), Hyden (11) and North Mingenew (10).
Management
DPIRD's Seasonal Climate Outlook report is predicting high chances of warmer temperatures and reduced rainfall for the August to October period. Canola plants are more vulnerable to caterpillar damage when they are stressed due to dry conditions and when they are flowering.
DBM thresholds for control at late flowering (no moisture stress) are 100 or more per 10 sweeps and 150 to 200 caterpillars per 10 sweeps at pod maturation.
Some other helpful tips to consider when sweep netting crops are:
- A high proportion of small caterpillars (less than 3 mm) in a sample often indicates that caterpillar numbers will increase further.
- Regular assessments of the number of caterpillars 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. Caterpillar numbers may reduce in both cool, wet and windy conditions or fine and mild weather.
- When checking crops with a sweep net, be mindful that small native budworm caterpillars can easily be confused with DBM caterpillars in canola crops. DBM caterpillars are usually pale yellowish green and tapered at each end of their body and grow to about 10 mm long. They often wriggle rapidly when disturbed and will hang on a silken thread. Native budworm caterpillars are far more damaging as they grow to larger sizes (up to 40 mm long) and will chew into the pods.
DPIRD research trials have showed that late season application of insecticide (especially multiple sprays) against DBM is less likely to result in a profitable outcome than early and mid-season pest control. This is mainly because DBM have less impact on yield once crops stop flowering. Visual surface grazing and scarring of pod walls and stems will occur from DBM caterpillars feeding in the late season. This may result in a minor reduction of grain filling capacity depending on the number of caterpillars, soil moisture levels and length of time to harvest. For this reason, the threshold of DBM numbers required to justify spraying will increase over time.
Growers considering late applications of insecticides need to be mindful to adhere to label withholding periods prior to swathing/harvest. Pesticide options for the control of DBM can be found in DPIRD’s 2023 Winter Spring Insecticide Guide.
New product registered for DBM in canola
Growers and agronomists should be aware that the active ingredient cyantraniliprole is now registered for use on DBM in canola.
More information
For more DBM information refer to:
- DPIRD’s diagnosing diamondback moth
- GRDC's fact sheet diamondback moth
- GRDC’s video managing diamondback moth.
For more information contact Research scientist Svetlana Micic in Albany on +61 (0)8 9892 8591 or Technical officer Alan Lord in South Perth on +61 (0)8 9368 3758.
Article author: Bec Severtson (DPIRD Northam).
Native budworm caterpillar update
- Northern agricultural region
- Eastern agricultural region
Increasing numbers of native budworm caterpillars have been reported lately in some parts of the eastern and northern agricultural regions.
This is a timely reminder for growers to be vigilant and monitor for caterpillars, especially as many crops are moisture stressed and at late flowering or pod fill stage.
Ty Henning (Ty’s Agri) reports finding eight caterpillars (<15 mm to >20 mm long) per 10 sweeps in a canola crop at pod fill stage near Cadoux.
Dan Taylor (DKT Rural) reported 20 to 30 budworm caterpillars per 10 sweeps in moisture stressed canola and lupin crops near Bodallin. A grower has found one caterpillar per 10 sweeps in chickpeas at Southern Cross, and an average of two caterpillars (10 mm long) per 10 sweeps have been found on canola at Varley.
The Mingenew Irwin Group (MIG) reports that they found between 14 and 41 caterpillars in 10 sweeps at West Mingenew, and zero to two caterpillars in 10 sweeps at North Mingenew. Both crops are at late flowering and pod fill stage and moisture stressed.
Dave Nicholson (DPIRD) reports increasing numbers of caterpillars in some canola crops. The areas with the highest average caterpillar counts per 10 sweeps are Dandanning with 10, Karloning with 5 and Merredin with 3. When sweepnetting crops at Kondinin, Hyden, Narembeen and Kellerberrin an average of less than one caterpillar per 10 sweeps was netted.
Andrew Phillips (DPIRD) has found up to six native budworm caterpillars in 10 sweeps in canola at Wicherina and noted that this crop had a lot of wild radish present. No budworm caterpillars were found at Nolba, Eradu, Yallabatharra and Moonyoonooka.
Canola pods become attractive to caterpillars of all sizes as the crop nears maturity and begins to hay-off. Larger caterpillars do the most damage. Narrow-leafed lupin pods and seeds can be damaged by native budworm close to maturity and when the pods are losing their green colouration. Field pea, chickpea, lentil and faba bean crops are very susceptible to all sizes of caterpillars during the formation and development of pods.
Moth trapping update
- Usual trapping locations
Ty Henning (Ty’s Agri) reports a capture of two native budworm moths in a trap near canola at Cadoux.
Andrew Phillips (DPIRD) reports the following moth counts from the Geraldton area: Wicherina (15 moths), Nolba (3), Eradu (10), Yallabatharra (6) and Moonyoonooka (9). These areas have reported higher moth numbers in previous weeks.
Low numbers of moths were caught in pheromone traps in the past week in DPIRD’s GRDC funded surveillance program. The moth captures recorded were: Bindi Bindi (64 moths), Cuballing (26), Grass Patch West (24), North Kellerberrin (11), Dowerin lupin crop (13), Dowerin canola crop (6), Badgingarra (7), Nth Cunderdin (5) Tincurrin (2) and Southern Cross (2). No moths were caught at Kojonup, Narrogin, Pingrup and Boyup Brook.
In the past fortnight, the following number of native budworm moths were also recorded: Varley (40 moths), Coorow (34), Doodlakine South (13) and Maya (12).
More information on native budworm is available in the 2023 PestFacts WA Issue 9 article native budworm are active early.
A mapped view of all recent native budworm trap captures is available at Cesar Australia’s MothTrapVisWA page. Viewers need to select the desired trapping date range.
Pesticide options for the control of native budworm can be found in DPIRD’s 2023 Winter Spring Insecticide Guide.
Growers and agronomists should be aware that the active ingredient cyantraniliprole is now registered for use on native budworm and diamondback moth on canola.
Detailed information on this pest can be found at the department’s management and economic thresholds for native budworm.
For more information, contact Technical Officer Alan Lord in South Perth on +61 (08) 9368 3758 or +61 409 689 468.
Article author: Bec Severtson (DPIRD Northam).