Forecasting the incidence of virus yellows in sugar beet in England

A new forecasting system for virus yellows incidence in sugar beet in the UK has been devised using multiple regression analyses. The forecast equations include data on (1) the previous year's virus incidence, (2) temperature in January and February and (3) the timing of the spring migration of Mytus persicae. Forecasts using the first two of these variables account for 63% of the variance in virus incidence in the main beet growing area of Eastern England and give growers information in time to decide on whether to apply aphicidal granules at drilling to control the vectors of the disease. Forecasts using all three variables account for 87% of the variance in virus incidence and can forewarn growers and the sugar industry of the likelihood of an epidemic. Forecasts for the northern and western regions of the beet growing area are derived from the forecast for the eastern region.