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Causal organism - Rhizoctonia cerealis
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The fungus overwinters primarily as mycelium on infected stubble. Volunteers and some grass weeds may also act as sources of inoculum . The fungus can also produce sclerotia which may act as overwintering structures. Infection may occur at any time during the growing season, but the disease is favoured by temperatures of around 9°C. Acid, dry and sandy soils and early sowing also favour the disease. Cool autumn or spring temperatures may result in early infection by the fungus which can lead to severe disease.
Sharp eyespot is common in the UK although, nationally, it does not usually cause significant yield loss. Individual crops may suffer significant loss, particularly if the disease is present with take-all, but nationally the losses due to the disease are very small. Severe sharp eyespot has been shown to reduce yield by up to 25% but this is very unusual. Annual losses in the UK on average are probably less than 0.5%.
