Canola growers across Australia are facing a growing challenge as the turnip yellows virus (TuYV) threatens their crops. This insidious pathogen, spread by the green peach aphid, has the potential to cause significant damage, with losses of 10-20% and sometimes even up to 50% in severe cases. What makes this issue particularly concerning is that TuYV cannot be cured once plants are infected, and symptoms may not appear until weeks or months after transmission. This means that growers need to be proactive in their monitoring and management strategies.
The Department of Primary Industries and Regional Development (DPIRD) has contributed to a new fact sheet, 'Manage Turnip Yellows Virus in Canola', which provides crucial information for optimizing crop potential. Ben Congdon, a senior research scientist at DPIRD, emphasizes the variability of TuYV infections, which can be difficult to distinguish from nutrient deficiencies and environmental stresses. Foliar symptoms, such as leaf purpling or reddening, may not be apparent until later stages of infection, making it challenging to manage the disease effectively.
One of the key recommendations is the importance of monitoring all canola crops, even those sown with neonicotinoid seed treatment, which has been found to no longer provide adequate protection against the green peach aphid. Removing broadleaf weeds and volunteers near canola paddocks can help reduce the presence of aphids and the virus reservoir. Foliar insecticides are the primary method for controlling TuYV, but they must be applied carefully and only when necessary.
Congdon highlights that pre-emptive spraying is unlikely to be effective, as the virus can spread rapidly once present. The timing of infection is critical, with the greatest damage occurring when plants are infected during early development, from emergence to the seven-leaf stage. The severity of yield losses depends on the percentage of the crop infected and the speed of spread. Therefore, growers need to be vigilant and consider management strategies that focus on early detection and targeted insecticide applications.
As the growing season progresses, DPIRD's monitoring in the Northam, Geraldton, Albany, and Esperance areas will provide valuable insights into TuYV risk. Growers and advisers are encouraged to share paddock intelligence through the PestFacts WA Service, ensuring that they stay informed and take proactive measures to protect their canola crops from this growing threat.
