Agronomist, David Jarrott (IK Caldwell), reports seeing aphids on volunteer canola around Deniliquin, in the Riverina district of New South Wales. David says moderate numbers of aphids have been found on the undersides of leaves and colonising the growing points of plants. To date, there have been no reports of aphids attacking emerging canola crops.
There are three major canola aphid pests in southern Australia: the cabbage aphid (Brevicoryne brassicae), the turnip aphid (Lipaphis erysimi) and the green peach aphid (Myzus persicae). In most cases, canola aphids do not cause significant problems in autumn and/or early winter. Large numbers of green peach aphids occasionally occur on young vegetative canola, and will require chemical control.
Canola crops are most susceptible to aphid damage from bud formation to late flowering when heavy infestations can lead to wilting, flower abortion and reduced pod set. The impact of aphids will be far more pronounced in crops that are moisture stressed, whereas adequate soil moisture can mean crops suffer little or no yield loss even with high aphid populations.
None of the abovementioned aphid species attack cereals. Growers should not be concerned about the presence of aphids on volunteer canola and brassica weeds in (or near paddocks) that have been sown to cereals. These aphids will not transfer across to emerging cereal seedlings. However, the presence of moderate numbers of canola aphids at this time of year, should serve as a reminder to closely monitor canola crops in spring, as populations begin to build up.
Click here for further information on canola aphids.