Aphids are active in canola crops
Crop protection officer Bec Swift (DPIRD) has reported finding cabbage aphids on canola in a trial site at Nunile. The canola plants were at the pod ripening stage.
Plant pathologist Kylie Chambers (DPIRD) has found high levels of green peach aphids (GPA) and low levels of cabbage aphids in a canola crop near Brookton.
Development officer King yin Lui (DPIRD) recently reported finding cabbage aphids in pod ripening canola near Scaddan.
Growers and consultants are advised to re-check canola crops for aphids, even if they have been previously sprayed, especially if the crop has experienced frost. They also need to check canola crops for fungal infections and parasitisation in aphids before deciding to invest in an insecticide spray. For more information see the department’s Know what beneficials look like in your crop.
The spray threshold of 20% of plants infested with colonies of cabbage or turnip aphids is not applicable at the advanced podding/grain fill stage because the research for thresholds had focused on flowering crops and effects on flower abortion and reduced seed set. Trial work conducted in Queensland on cabbage aphids suggests that infestations after bolting are not yield limiting, however DPIRD trials have shown that very high numbers of cabbage aphids on pods can cause shrivelled seed during seed filling stage. For more information refer to the GRDC Update paper Insect Pest Management Research Update 2017.
Growers are reminded to abide by the withholding periods on the product labels.
For more information on identifying and managing canola aphids refer to;
- DPIRD’s 2019 PestFax Issue 18 article Cabbage, turnip and bluegreen aphids
- 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 Managing cabbage aphids YouTube video.
Article authors: Cindy Webster (DPIRD Narrogin) and Dusty Severtson (DPIRD Northam).