USE OF A DISEASE FORECASTING SYSTEM TO MANAGE STRAWBERRY GREY MOULD

Grey mould of strawberry, caused by Botrytis cinerea Pers.:Fr., is one of the most important airborne diseases of strawberry and can seriously reduce yield and post-harvest fruit quality. Grey mould results mainly from latent infection of flower parts, which develop into rots once fruit begins to ripen. Current control of grey mould relies on scheduled application of fungicides during flowering and early fruiting period for open-field crops. Although risk of grey mould on crops under protection is greatly reduced, routine fungicide application is often used to control grey mould. We developed a disease forecasting system for strawberry grey mould. The forecasting model uses day vapour pressure deficit and night temperature to predict the daily incidence of flower infection by B. cinerea and subsequent fruit infection. A series of experiments were conducted on both open-field and protected crops of cultivar ‘Elsanta’ to evaluate the usefulness of this system for practical disease management. Overall, the incidence of grey mould at harvest was very low, even on open-field untreated plants. However, there were significant differences in the level of post-harvest Botrytis among treatments. All model-based treatments reduced the incidence of grey mould in post-harvest tests, compared to the untreated. Overall, the model-based strategies achieved comparable success in controlling grey mould to the conventional strategy but with reduced fungicide input. The exact reduction in fungicide use varied greatly among years, ranging from 10 to 60%. Overall, it appears that the risk of grey mould on early-covered crops of ‘Elsanta’ is minimal and fungicide application against grey mould during flowering and fruiting appears thus to be not necessary.