Sharp eyespot symptoms in cereals

Sharp eyespot lesions are largely superficial and the disease is not related to the more serious eyespot disease. Find out about the pathogen and the symptoms seen on infected cereal crops.

The disease affects wheat, barley, oats, rye and triticale.

The fungus – Ceratobasidium cereale (Rhizoctonia cerealis) – is relatively common in the UK.

Average annual yield losses are probably less than 0.5%.

On rare occasions, severe sharp eyespot may reduce yield by up to 25%.

The most significant losses tend to be associated with the presence of take-all disease.

The pathogen overwinters primarily as mycelium on infected stubble, but also on volunteers and some grass weeds.

The fungus can produce sclerotia, which may act as overwintering structures.

Infection occurs at any time during the growing season.

Cool autumn or spring temperatures (around 9°C) are associated with earlier infection and more severe disease.

Disease also tends to be higher in acidic, dry and sandy soils.

Symptoms occur as sharply defined lesions on the outer leaf sheaths.

Young lesions have a clear, dark margin and, frequently, the epidermis within the lesion is shredded.

Multiple lesions can be found up the stem, up to 30 cm away from the stem base.

Later in the season, lesions on the stem have a pale cream centre with a dark brown, sharply defined edge.

Sharp eyespot lesions are often superficial, distinguishing it from eyespot where lesions may penetrate one or two leaf sheaths.

Severe sharp eyespot can cause white heads or lodging.