MONITORING REGIONAL DISEASE RISK

Data from the Defra Winter Oilseed Rape Survey of England and Wales for the years 1990 to 1999 have been used to generate maps illustrating overall risk of individual diseases over this period. Data for light leaf spot, phoma canker, alternaria pod spot and sclerotinia stem rot are presented.
The survey data have been interpolated by kriging to produce a continuous surface of disease incidence. In order to restrict the maps to only those locations where winter oilseed rape is grown, the data have been plotted onto a grid mask of the winter oilseed rape cropping area.

	Mapping of incidence of light leaf spot in spring shows that the risk of infection is highest in the north and west of England. A more detailed analysis of these data has produced a disease forecast for light leaf spot which can be accessed at the following address: www3.res.bbsrc.ac.uk/leafspot To view map click here
	Phoma canker is now the the common disease of winter oilseed rape with highest risks of disease occuring in the eastern and central counties of England. Further analysis to develop a risk forecast for the disease are currently being undertaken and the resulting model will be validated during 2001/2002. To view map click here
	Incidence of alternaria pod spot has been very variable over the last ten years, depending on weather conditions. Risks are highest in the south. To view map click here
	Risks of sclerotinia are generally low and localised. The last major epidemic occured in 1991. When conditions are conductive for disease development, risks have been highest in the Herefordshire area. To view map click here