Efficiency of inorganic fungicides against the formation of Erysiphe necator chasmothecia in vineyards.

The application of inorganic fungicides reduced the amount of chasmothecia as the primary inoculum source. Potassium bicarbonate and copper are of further interest for disease control, as these fungicides can be used by organic and conventional wine growers. The application of these fungicides should be carried out as late as possible before harvest to reduce chasmothecia formation and, consequently, the potential for powdery mildew infestation in the subsequent season.