Stem rust (Puccinia graminis subsp. graminicola) is the most damaging of the ryegrass diseases. This update discusses how different fungicide programmes and timings affect seed yield. It compares early versus late applications and offers practical advice to help growers improve rust control and maximise returns.
Key points
- Left unmanaged, stem rust and other diseases can cause severe perennial ryegrass seed yield losses.
- In ten FAR field trials across Canterbury, fungicide programmes increased perennial ryegrass seed yield by an average of 77%.
- Applying fungicides at GS 32, head emergence and flowering, consistently delivered the highest seed yield improvements.
- A ‘flowering +14-day’ application should be applied only in seasons with late rust pressure.