OCCURRENCE OF AMPELOMYCES QUISQUALIS ON THE CUCURBIT POWDERY MILDEW SPECIES IN THE CZECH REPUBLIC

Abstract

From 2002 to 2006, in the Czech Republic (CR), 585 leaf samples with powdery mildew symptoms collected from cucurbits (mainly from Cucurbita pepo, Cucurbita maxima, Cucumis sativus) were microscopically examinated for presence of hyperparasitic fungus Ampelomyces quisqualis Ces. (Aq). Identification of cucurbit powdery mildew species (Golovinomyces cichoracearum /Gc/, Podosphaera xanthii /Px/) was carried out by microscopic examination of the morphological characters of dry conidia in a 3% KOH solution. In total of 443 samples was determined as Gc, 106 samples as mixed infection (Gc, Px) and 36 samples as Px. Aq was detected on 12% of collected samples from the CR. However, frequency of its occurrence varied among the years. In 2002 and 2006, Aq was more frequent (18-20%) as compared with the years 2003-2005 (only 6-8%). Pycnidia of Aq were recorded mainly on Gc hyphae and basal cells of conidiophores (12%) or on mixed infection (Gc, Px) (14%). Occurrence of Aq on Px was only sporadic (only 3 CPM samples/2 locations - 2/1 in 2005 and 1/1 in 2006). Its distribution was recorded in 52 locations of the CR, it was not restricted to limited areas, nevertheless the most of Aq locations originated from the South Moravia. In some locations its presence was recorded repeatedly, in some others it was detected only once. The majority of samples with presence of Aq were collected in August and September.