Canola growers across Australia are facing a growing challenge as the turnip yellows virus (TuYV) poses a significant threat to their crops. This disease, spread by the green peach aphid, is particularly insidious due to its ability to cause substantial yield losses, sometimes even without visible symptoms. With warmer temperatures and recent rainfall, conditions are ideal for the aphid and the virus, making it crucial for growers to take proactive measures.
The Department of Primary Industries and Regional Development (DPIRD) has issued a stark warning, emphasizing the need for vigilant monitoring and early action. Ben Congdon, a senior research scientist at DPIRD, highlights the difficulty in distinguishing TuYV infections from nutrient deficiencies and environmental stresses. Symptoms, such as leaf purpling or reddening, may not appear until weeks or months after the virus has taken hold, making it challenging to manage effectively.
One of the most concerning aspects of TuYV is its impact on canola crops. Once infected, plants cannot be cured, and yield losses can range from 10 to 20 percent, with severe cases reaching up to 50 percent. This highlights the importance of early detection and management.
Congdon recommends a multi-faceted approach to combat TuYV. Removing broadleaf weeds and volunteers near canola paddocks can reduce the aphid population and virus reservoir. Foliar insecticides are the primary tool for targeting aphid infestations, but their effectiveness is highest during the early stages of crop development.
The timing of infection is critical. Plants infected during the early development stages, from emergence to the seven-leaf stage, are more susceptible to severe damage. The percentage of the crop infected and the speed of spread are key factors in determining potential yield losses.
A comprehensive fact sheet, developed by DPIRD and the Grains Research and Development Corporation (GRDC), provides valuable guidance on monitoring green peach aphids and targeted insecticide applications. However, Congdon warns against pre-emptive spraying, which is unlikely to provide adequate control. Instead, growers should focus on careful monitoring and targeted interventions.
As TuYV continues to spread across Australia, the failure of neonicotinoid-based seed treatments to control green peach aphids has exacerbated the problem. This has led to a growing need for innovative management strategies to protect canola crops. Growers and advisers are encouraged to share information through the DPIRD's PestFacts WA Service, utilizing the app to report aphid observations and contribute to ongoing research efforts.
In conclusion, the battle against TuYV requires a combination of vigilance, early action, and strategic management. By staying informed and adopting appropriate measures, canola growers can mitigate the impact of this insidious virus and safeguard their crops for the future.
