Archivio Journal of Plant Pathology

Abstract:

Erisyphe necator is one of the most destructive pathogens of grapevines and is normally controlled by seven and more fungicide treatments until veraison of grapes. Two fungicide regimes comprising either 3 or 7 sprays per season were compared in a German vineyard between 1999 and 2010. The trials always included: (i) 3 fungicide sprays, one before flowering, the second during blossoming and the third at berries diameter 2 mm [so called “Open Window Period” (OWP) sprays]; (ii) 7 sprays which included OWP sprays of (i) plus one spray before and three afterwards. The trials were carried out with a single line tunnel-sprayer in 4 replicates, each comprising 12 vines of highly susceptible varieties. Experimental rows were separated by untreated rows on both sides. Although in most years, natural initial inoculum was present, in 2008-2010, the initial inoculum was supplemented with artificial infections on the separating untreated spacer lines. Even under extreme disease pressure, 3 sprays in OWP had nearly the same and always more than 90% of the preventive effect of seven sprays.