Turnip yellows virus (TuYV) and its vector, green peach aphid (GPA), pose a serious threat to canola crops this season, with recent research showing that neonicotinoid seed treatments no longer offer adequate protection.
Warmer temperatures and recent rainfall have created favorable conditions for green peach aphid (GPA), the insect vector that spreads Turnip yellows virus (TuYV). Canola growers are urged to monitor crops closely and take early action, as foliar insecticides are now the only effective option after sowing.
Disease Impact and Key Facts
TuYV is a significant disease that can cause 10–20% yield losses, and in some severe cases up to 50%. The virus was formerly known as beet western yellows virus.
- No cure for infected plants: Greatest damage occurs when plants are infected from emergence through the seven-leaf stage.
- Seed treatments ineffective: Recent research confirms that neonicotinoid seed treatments no longer provide adequate protection against GPA or TuYV.
- Foliar sprays are the only option: When applied early during GPA infestation and crop development, foliar insecticides are most effective.
Monitoring and Management Guidelines
Growers should not rely on visual symptoms alone to guide spray decisions.
Foliar symptoms—such as leaf purpling or reddening—may be mild or even absent, and they often appear weeks after infection has already occurred. By the time symptoms are visible, significant yield loss may have already happened.
Key management steps include:
- Remove broadleaf weeds and volunteer canola plants near paddocks to reduce aphid numbers and the virus reservoir.
- Pre-emptive spraying is not recommended; spraying once the virus is widespread provides no benefit.
- Report GPA observations using the PestFacts WA Service app to help with regional monitoring.
Monitoring Locations
The Department of Primary Industries and Regional Development (DPIRD) is conducting monitoring in:
- Northam
- Geraldton
- Albany
- Esperance
Additional Resources
A new GRDC fact sheet, "Manage Turnip Yellows Virus in Canola," is now available. It provides detailed monitoring guidelines and insecticide application advice for growers.