Grass Diseases

Grass Disease Identification

Ryegrass Mosiac Virus

The most important viral disease affecting ryegrass. Symptoms are more common in Italian than Perennial varieties. The virus is transmitted through a mite that thrives in dry conditions and so it is more prevalent in the East of England. Can also infect cocksfoot. Appears as light green to yellow mosaic pattern on leaves, which decreases the vigour of the plant. Severe cases can result in leaf death.

Brown Rust - Puccinia sp.

Brown Rust occurs early in the season, during April and May and throughout England and Wales.

It only affects ryegrasses and is a different species to the brown rusts that infect wheat and barley. It can reach moderate levels in some varieties, but most have good resistance.

Crown Rust - Puccinia coronata

Characterised by scattered orange spores over the leaves, seen in late August and September. 

Occurs with high rates of grass growth combined with warm days and dewy nights. Tends to reduce yield as a result of plant stress and decrease in palatability. Spread by wind and rain splash. A problem particularly in the southwest of England and Wales.

Leaf Spot - Drechslera sp.

A fungal infection that produces brown spots surrounded by yellowing tissue, which is encouraged by wet and cloudy weather.

Cattle reject infected areas leading to excess growth and more disease build up. Spread by spores, wind and rain.

Powdery Mildew - Blumeria graminis

Characterised by white “sappy substance” and becomes more active during the spring and autumn periods.

Spores are produced in warm, humid conditions and damage leaf area, reducing yield and palatability. Particularly susceptible plants are the faster growing ryegrasses species such as Italians.

Spread by wind and rain splash and remain dormant through winter periods to become active early spring.