Reducing primary inoculum sources of grapevine powdery mildew by the hyperparasite Ampelomyces quisqualis

Abstract: The present study addresses the occurrence of artificial parasitism of grapevine powdery mildew chasmothecia by Ampelomyces quisqualis and aims to explore new methods for managing powdery mildew infections under field conditions. Conidia of the hyperparasite were rarely detected in mature chasmothecia with fully developed appendages. In contrast, the large number of fully developed chasmothecia without asci and ascopores were considered to be parasitized by the mycoparasite. Infested chasmothecia do not reach the stage of maturity, do not form appendages nor ascospores, which is linked with the reduction of the source of primary infections. To conclude this study underlines a good effectiveness of this hyperparasite in terms of reduction of overwintering chasmothecia in its natural environment.