Open AccessOccurrence ofErysiphe necatorChasmothecia and Their Natural Parasitism byAmpelomyces quisqualis
Author(s) -
D. Angeli,
E. Pellegrini,
I. Pertot
Publication year - 2009
Publication title -
phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.264
H-Index - 131
eISSN - 1943-7684
pISSN - 0031-949X
DOI - 10.1094/phyto-99-6-0704
Subject(s) - powdery mildew , biology , conidium , pycnidium , parasitism , botany , mycelium , horticulture , host (biology) , ecology
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 development pattern, and the incidence of parasitism by A. quisqualis were assessed. The production of E. necator chasmothecia on leaves is related to the incidence and severity of the disease on leaves at the end of the season and is not correlated with the elevation of the vineyard, which is inversely related to the temperature. A limited amount of natural parasitism of E. necator by Ampelomyces spp. (0.17 to 3.51%) was observed in all of the years of the survey. Pycnidia and conidia of Ampelomyces spp. parasitizing E. necator chasmothecia were found in conventional, organically grown, and untreated vineyards. Some of the isolated Ampelomyces strains have conidia that are shaped differently than those of the commercial A. quisqualis strain (AQ10) and are phylogenetically different from AQ10.