Turnip yellows virus and green peach aphid detected in yellow sticky traps and canola crops
- Geraldton port zone
- Kwinana West port zone
- Albany port zone
- Esperance port zone
DPIRD’s aphid trapping program and reports from regional consultants are finding that green peach aphids (GPA) are becoming increasingly active across the grainbelt, increasing the risk of turnip yellows virus (TuYV) infection in canola. This is shown in the map above.
The risk of yield losses from TuYV is highest when both GPA and TuYV are present and spreading through the crop prior to flowering. Any virus transmission that occurs after flowering has begun is unlikely to cause yield loss.
In the Geraldton region, Geoff Fosbery (ConsultAg) has reported finding GPA in 6 – 7 leaf canola plants near Geraldton. Some canola plants are also displaying potential TuYV infection but have yet to be tested. There have also been reports of GPA and canola with visible feeding damage at Yardarino. The crop has a mix of growth stages. There have been reports of GPA causing significant feeding damage to canola near Dongara. This activity is noticeable on both light and clay soils. In one case aphid numbers and the feeding damage were significant enough to warrant spraying with MainMan insecticide. In another case the GPA were damaging canola that had been previously fed on by lucerne flea. These crops have also not been tested for virus. Aphid activity has been minimal at trapping sites located at 4-5 leaf canola crops growing at Nangetty, Moonyoonooka and East Nabawa.
In the Northam region, GPA was found in canola crops at trapping sites at Northam and Narraloggan in early June. TuYV has been repeatedly detected in aphids caught at the Northam site from early June. Although it has yet to be detected in the canola crop, TuYV risk is elevated due to the presence of both the virus and the vector, especially in pre-flowering canola crops. GPA has yet to be found at trapping sites located at Nunile and Bolgart.
In the Albany region, cabbage and turnip aphids carrying TuYV were detected from 14 May to the present at trapping sites located at Kendenup, Tenterden, South Stirlings and Cranbrook. At Kendenup, large numbers of aphids were caught migrating out of a dual-purpose canola crop which likely had high levels of TuYV infection. However, GPA has not been found in traps or in the crops at these sites, nor at Frankland, Amelup, Scotts Brook or Kojaneerup. This indicates that the TuYV risk is low in Albany port zone, especially since many of these crops are close to stem elongation.
In the Esperance region, GPA and TuYV have been detected on traps among a small number of aphids caught at Munglinup. Furthermore, TuYV was detected in the crop at low levels (estimated 2% of plants). Aphids of various species have been caught at Cascade, Speddingup, Gibson, Coolinup and Howick, but GPA or TuYV have not been detected among them. Crops at these sites range from the 2 leaf stage to early flowering.
Management
Risk of yield-limiting disease from TuYV infection is elevated in pre-flowering canola crops in which both TuYV and GPA are present in combination. As day length and daytime temperatures increase over the coming months, GPA will continue to build up in canola crops across the WA grainbelt. In regions where TuYV and GPA are present, crops still in the early vegetative growth stages may still be at risk if they are still in the pre-flowering growth stages over the next 4 to 6 weeks.
Depending on the progress of virus infection, a single application of insecticide while the crop is still in early growth stages may be beneficial in suppressing GPA populations in the crop and subsequent TuYV spread. Prevention is crucial to virus management as viruses cannot be sprayed out. So once infection reaches high levels, a spray application will not have any impact.
Crops that have begun stem elongation and have not had significant TuYV infection are now considered in the safe zone. This means that the use of insecticides to control GPA/TuYV in these more mature crops is unlikely to provide any economic benefits.
If growers or agronomists operating in these regions observe aphid infestation or virus-like symptoms in crops, please contact DPIRD Research Scientist Benjamin Congdon via email at Benjamin.Congdon@dpird.wa.gov.au.
Effective chemicals currently available in Australia for control of GPA are alarmingly limited as GPA has evolved resistance to many insecticide chemicals. For more information see GRDC’s Aphid and insecticide resistance management in grain crops.
For registered insecticide recommendations, refer to DPIRD’s 2024 autumn winter insecticide guide.
Further information
This trapping surveillance is funded by the GRDC project DAW2305-003RTX “Effective virus management in grains crops”.
To read about earlier aphid surveillance findings this season and management advice refer to the 2024 PestFacts WA Issue 6 article Canola aphid and virus update and Issue 4 article Turnip yellows virus detected in migrating cabbage aphids.
For more virus management information refer to DPIRD’s Managing barley yellow dwarf virus and cereal yellow dwarf virus in cereals and Turnip yellows virus in canola: diagnosis and management pages.
For further information contact Research Scientist Benjamin Congdon, Perth via email at Benjamin.Congdon@dpird.wa.gov.au .
Article authors: Benjamin Congdon (DPIRD Perth) and Cindy Webster (DPIRD Narrogin).