Turnip Yellows Virus (TuYV) has emerged as a significant challenge for canola growers across Australia in recent seasons. The 2024 season saw notable outbreaks in NSW, with WA, SA and VIC also affected. In severe cases, yield reductions of up to 70% have been recorded in affected plants. Because there is no cure once plants are infected, protecting yield potential relies on minimising virus spread early in the season.
Understanding the Risk
TuYV is spread by aphids, with Green Peach Aphid (GPA) recognised as the primary and most efficient vector in Australian canola crops. While other aphid species can transmit the virus, GPA is generally the main driver of economic damage. Early aphid incursions are a key reason the virus can spread rapidly. Crops sown early are often at greater risk, particularly where seed-treatment protection declines while aphid activity remains high. Even low aphid numbers are capable of transmitting TuYV. This makes early monitoring and a planned aphicide strategy essential to reduce exposure during the most vulnerable growth stages.
Monitoring Through the Critical Window
The period from crop emergence through to stem elongation is when TuYV infection has the greatest impact on yield. Monitoring should begin at emergence and continue through early vegetative growth. During warm, mild conditions that favour aphid activity, inspection frequency should increase.
High-risk situations include:
- Early-sown canola
- Paddocks near "green bridges" such as weeds or volunteer canola
- Areas of the crop where aphids are first likely to colonise, including edges
Regular crop checks and recording aphid presence alongside crop growth stage allow timely decisions before populations build and virus spread accelerates.
Why Mode of Action Matters in TuYV Situations
When managing aphids in a virus scenario, speed of feeding cessation is critical. TuYV is transmitted when aphids probe and feed. The longer feeding continues, the greater the opportunity for virus spread within the crop. Aria® 500 WG works by rapidly stopping aphid feeding behaviour. After exposure:
- Aphids stop feeding within 15 to 30 minutes
- Feeding cessation helps limit further TuYV transmission
- Aphids become lethargic and inactive before dying within 3–4 days
Although mortality occurs over several days, the rapid stop feeding is the key benefit in managing virus risk.
In addition, Aria® 500 WG:
- Provides a unique mode of action to support resistance management
- Is IPM-friendly and soft on many key beneficial insects
- Delivers residual activity to help protect crops during vulnerable growth stages
Early Intervention Protects Yield Potential
Turnip Yellows Virus is a major threat to canola production, particularly where early aphid pressure is present. By monitoring crops from emergence, identifying high-risk paddocks, and selecting aphicides that rapidly stop feeding, growers can reduce the risk of TuYV spread and better protect yield potential. In TuYV management, early action is not just about reducing aphid numbers – it is about preventing virus transmission when it matters most.
Useful links:
Cesar Australia – Green peach aphid and turnip yellows virus: Addressing your questions – Cesar Australia