Oilseed rape diseases on the up

DISEASE PRESSURE on oilseed rape crops across the country is growing, but wet ground conditions are hampering control, according to latest reports.

In much of England and Wales, phoma incidence is on the rise following recent spells of frequent, prolonged rainfall, the latest Crop Monitor results show.

But in Scotland, light leaf spot is more of a concern, with the biggest problem being saturated soils preventing farmers getting on with fungicide applications, said the Scottish Agricultural Collegeā€˜s Keith Dawson.

Of all the Crop Monitor sites, phoma leaf spot levels are highest at the Terrington, Wolverhampton and Kent sites, where over 50% of plants are affected.

Even in traditionally low risk areas, such as parts of the South West, the disease is starting to be seen, with some crops just reaching the treatment threshold of 10-20% of plants affected, the report shows.

Warm and damp conditions early in the growing season, combined with cooler, wet soils now are “very conducive to light leaf spot,” Dr Dawson said.

Downy mildew was also a problem in some backward crops, but light leaf spot remained the biggest problem in nearly all crops, he said.

Around 10-15% of crops had been treated so far, he estimated, but waterlogged soil preventing farmers getting on fields was causing a very big concern.

“Autumn disease control is absolutely crucial in Scotland. There are concerns for the winter hardiness of oilseed rape crops.”