Canola farmers in South Australia are facing a formidable challenge as the Turnip Yellow Virus (TuYV) wreaks havoc on their crops. This insidious virus, spread by the Green Peach Aphid, has the potential to decimate entire fields, leaving behind a trail of yellowing and purpling leaves. The severity of the outbreak is alarming, with reports of nearly 100% infection rates in some paddocks. Dr. Nicole Thompson, an expert in the field, emphasizes the importance of early detection and swift action. She recalls a harrowing incident where a forage canola crop in the Padthaway/Bordertown area showed symptoms of TuYV infection just two weeks after being infested with aphids. This underscores the critical need for farmers to remain vigilant and inspect their crops thoroughly throughout the growing season.
The Green Peach Aphid, the vector of TuYV, is particularly insidious. It thrives in 'green bridges' - perennial weeds, forage brassica, volunteer canola, and new canola crops. Once the aphids feed on infected plants, they become infective and spread the disease further. Dr. Thompson highlights the difficulty in diagnosing TuYV in the field due to its non-symptomatic nature, making early detection even more crucial. The webinar, attended by industry experts, underscored the importance of timely spray applications and the potential resistance of certain pesticides like Versys and MainMan.
However, the battle against TuYV is not the only concern for canola farmers. Sclerotinia stem rot, another formidable disease, has been detected in areas across Victoria and New South Wales. Dr. Kurt Lindbeck, a pulse and oilseed pathologist, advises farmers to exercise caution when considering fungicide use. The optimal timing for fungicide application is during the 20-30% flowering stage, which corresponds to 15-20 open flowers off the main stem. This stage marks the beginning of significant shedding or senescence of petals, triggering stem infections. Lindbeck emphasizes the importance of good coverage and penetration, especially with high water rates and finer droplet sizes, to ensure effective control of this disease.
As the agricultural season progresses, farmers must remain vigilant and proactive in their disease management strategies. The potential impact of these viruses on crop yields and profitability cannot be overstated. It is a race against time, and the industry must rally together to find solutions and mitigate the damage caused by these insidious pathogens.
