| occurrence of erysiphe necator chasmothecia and their natural parasitism by ampelomyces quisqualis. | in northern italy, erysiphe necator overwinters almost exclusively as chasmothecia. from 2004 to 2008, we investigated the occurrence of natural parasitism of grapevine powdery mildew chasmothecia by ampelomyces quisqualis in the trentino-alto adige region, in northern italy. the survey was conducted in 18 vineyards in autumn 2004 and 2005 and in 45 vineyards in autumn 2006 and 2007. the incidence of powdery mildew signs (white powdery mycelia and conidia), the number of chasmothecia and their d ... | 2009 | 19453229 |