Empirical models for prediction of regional light leaf spot (Pyrenopeziza brassicae) incidence on winter oilseed rape in the UK

Empirical models have been used to forecast plant disease epidemics and guide spray decisions. Light leaf spot (Pyrenopeziza brassicae) is a serious disease of winter oilseed rape in the UK, showing seasonal and regional variation in epidemics, as measured by percentage of plants with infected leaves in March or with infected pods in July. Work has started on a forecasting system for light leaf spot, to identify regions and crops at risk in each season. This paper describes the empirical modelling used to determine seasonal risk