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Common Eyespot
Tapesia yallundae & Tapesia acuformis
General Description
Common eyespot is a fungal disease which attacks the stems of winter cereals.
Winter wheat is affected most, but winter barley can also be affected.
Spring crops and winter oats are not so badly affected by this disease.
The disease causes lesions around the stem after flowering, which affect the uptake of water and nutrients into the developing grains.
They also weaken the stem and most yield loss occurs when crops lodge.
Biology
The fungus can overwinter in trash, but is can also produce wind blown spores. Early sown wheat crops (i.e. August and early September) are most at risk. Crops grown under minimum tillage cultivations are at lower risk than under ploughing. Some varieties have good resistance, but there is also a yield penalty when they are grown. New varieties with disease resistance but no yield penalty are expected soon.
There are two species of eyespot, but they are still known as the W and R types. The R type is now common in the UK, having taken over from the W type, which was common in the 1980's. The R type develops later in the season and is more difficult to control with fungicides.
Diagnostics can help determine the presence of both species. The presence of eyespot only forms part of a risk assessment however. Presence of disease in the early spring cannot always be linked to disease severity at the end of the season.
A Judgement assistance tool developed at SAC takes account of all the risk factors. It is simple to use and can help determine which crops are at greater risk and hence require specific treatment at stem extension.
Advice
Use the SAC risk forecast to determine crops most at risk. This simple to use judgement assistance tool takes account of the key risk factors including the growers perception of the risk. Use the link on the right of his page.
Fungicides applied in the early spring at stem extension is the best time to protect crops from eyespot.