Crown Rust
Puccinia coronata
Pathogen
Fungus
Hosts
Oats, grasses especially perennial rye-grass.
Symptoms
First signs are small rounded orange-yellow coloured pustules, usually on both sides of the leaves. Later the pustules join together to form evenly affected areas. Small black pustules are produced late in the season.
Development
Infection comes from windborne spores arising from volunteer host plants.
Favourable factors
20 °C temperature with high humidity favours the disease.
Importance
Crown rust is host specific to oats (and some grasses). Because of the need for great warmth the disease occurs only shortly before harvest but it can cause large reduction in yield and quality.
Control
Removal of volunteers
Use of an effective fungicide programme
