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Tan spot in wheat

Pyrenophora tritici-repentis

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General Description

Tan spot in wheat is currently rare in Scotland, but the disease was found in 2010 in the Lothians.

Tan spot produces tan lesions on the leaves with a dark brown centre surrounded by a yellow border. Symptoms can be confused with Septoria nodorum, but the central dark spot is more typical in tan spot. It is rare in Scotland, but it appeared on wheat and barley in the summer of 2010 where average temperatures in July were high and leaves were wet for long periods of time.

The disease has been common in Denmark since 2000 in continuous wheat crops  grown using minimum tillage cultivations.  

Biology

This fungal disease can be present on the seed and also in crop debris. It is most common in wheat crops grown in short rotations where crop stubble and debris are presnet on or neath the soil surface. The symptoms appear after periods of warm and wet weather. Typically conditions in scotland will be too cool, but in July 2010, the warm and wet weather led to symptoms appearing on the upper leaves.

Advice

Fungicide treatments focussed on protecting crops from septoria tritici at flag leaf emergence and head emergence should provide effective control. The outbreak was identified in a crop where no head fungicide had been applied.

Diary

Resistance Issues

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Contact

Dr Fiona Burnett
SAC (Scottish Agricultural College) Work Crop & Soil Systems Research Group King's Buildings
Edinburgh
EH9 3JG
TelWork 0131 535 4133

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