Ampelomyces hyperparasites – occurrence and effect on the development of ascomata of Erysiphales species under conditions of anthropopressure

Fungi of the genus Ampelomyces are the major antagonists of Erysiphales fungi being a significant group of phytopathogens. The hyperparasites attack various developmental stages of powdery mildews. As a result the infested ascomata do not reach the stage of maturity, do not form appendages nor ascospores, which is linked with a reduction of the source of primary infections. Studies conducted so far have mainly been devoted to Ampelomyces fungi application in the biological control of powdery mildews on crops, whilst a few only have been focused on the ecology of these mycoparasites on Erysiphales fungi infecting plants, especially in the urban environment. The present study addresses the natural occurrence and effect of Ampelomyces fungi on the development of ascomata of powdery mildews species. The material was collected in 2005–2009 in several cities of the northeastern Poland. First time ever Ampelomyces spores are reported in mature ascomata of Erysiphales with fully developed appendages. This phenomenon has been observed in the case of two species, viz.: Erysiphe flexuosa on Aesculus spp. and E. vanbruntiana var. sambuci-racemosae on Sambucus racemosa and is presumably linked with improved implementation, propagation and probably better survival during winter months.