Early management decisions are key to reducing aphid and beet western yellows virus (BWYV) risk in 2015. Significant rainfall over much of the southern cropping zone in January 2015 has created a green bridge, which can host large populations of insects as well as viruses between growing seasons. This has increased the risk of further BWYV outbreaks this year.
cesar have recently teamed up with SARDI, NSWDPI, VicDEDJTR and GRDC to produce a list of management recommendations for grain growers when sowing in conditions of high virus risk. These have been published in GRDC Tips and Tactics, and include the following key recommendations:
• Controlling the green bridge, particularly volunteer canola, wild radish, wild turnip, marshmallow and other broadleaf weeds, which host BWYV and the principal vector, the green peach aphid (GPA). Apply appropriate herbicides soon after weeds begin to germinate. Re-apply herbicides after any further rainfall events that encourage additional weed germination.
• Use of canola seed treated with a neonicotinoid insecticide, and ensure proper application and coverage of the seed dressing for highest efficacy.
• Avoid sowing crops early in the season; sow on usual dates, to avoid early aphid flights.
• Where feasible, sow into standing stubble to reduce aphid landings.
• Sow at rates to achieve an even and uniform plant density that achieves quickest groundcover, to reduce aphid landings.
• Monitor seedling canola crops before the rosette stage for aphids and symptoms of virus. Aphids can be difficult to find when their population is low, but GPA are often found on the underside of the oldest leaves. Control aphids if required.
• Ensure correct identification of GPA before considering chemical sprays.
Cilck to download the full document: Tips and Tactics: Reducing aphid and virus risk (2015) (pdf)