Below average winter rainfall has reduced the light leaf spot risk to oilseed rape crops this season, according to the latest Rothamsted Research forecast.

The highest risk is in northern England and Scotland, where 54-73% of plants are predicted to be affected, whereas crops in East Anglia are at lowest risk (7% plants affected).

“The risk prediction for the midlands, south and west is comparable to last year,” commented Rothamsted’s Neal Evans.

“In the north, the original spring prediction made in September was perhaps higher than one might expect, but this was driven by high incidence of pod infection on a few crops.”

While the overall risk in many areas has been reduced following the dry winter, individual crops may still be at risk given the current milder and wetter weather, he said.

“Crops at most risk are those with small plants of a susceptible variety, especially in the north of England and Scotland.

He urged growers to inspect fields to ascertain incidence of light leaf spot in individual crops and consider a precautionary spray should incidence exceed 25% plants affected.

To view a crop-specific forecast, see http://www3.res.bbsrc.ac.uk/leafspot/