Widespread infestations of green peach aphids (GPA) (Myzus persicae) during autumn and winter have contributed to an outbreak of beet western yellow virus (BWYV) in southern Australia. Canola crops across the lower and mid north regions of South Australia, western Victoria and some parts of NSW have been severely affected by the virus.
Canola is most susceptible to BWYV at the rosette stage, when infection can lead to high yield losses. Generally, the yield consequences of BWYV decrease with infection at later stages of crop development. However, canola crops remain susceptible to yield losses from BWYV infection until approximately the mid-podding stage. BWYV is not seed-borne and requires an aphid host to spread. GPA is the principal vector of beet western yellow virus (BWYV),
In many cases, growers have been unable to achieve adequate control of GPA populations due to the prevalence of resistance of GPA to insecticides. High levels of resistance to carbamates (e.g. pirimicarb) and pyrethroids are now widespread across Australia. Moderate levels of resistance to organophosphates have been observed in many populations, and there is evidence that resistance to neonicotinoids (e.g. imidacloprid) is evolving. cesar is currently screening GPA populations for resistance using DNA diagnostic tools; these results are being used to assist growers with recommendations for spraying both pulse and canola crops.
It is important to only use insecticides registered for the crop and situation, to comply with the label directions for the application method, to not exceed application or frequency rates, and to follow all withholding periods. Take advantage of the GPA resistance maps to determine the most effective control method for your region.
The decision to spray GPA should consider the proximity and impact on local beehives. We recommend providing beekeepers with sufficient advanced notice so that bees can be withdrawn if necessary. Do not spray when bees are foraging.
Follow the link below to see a resistance map for your region:
New South Wales
If you have any queries, please feel free to contact us:
Dr Siobhan de Little
Phone: (03) 9349 4723