Invasive Species Compendium

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Abstract

Effects of temperature, relative humidity, pH and triazole fungicides on sporulation and conidial germination of Uncinula necator.

Abstract

An experiment was conducted to obtain basic information on the effects of environment and fungicides on the sporulation, conidial germination and initial growth of the hyphae of the grape powdery mildew fungus, U. necator. Maximum sporulation occurred at RH 76-96% in vitro, adjusted with sulfuric acid solution. Conidial germination and initial growth of the hyphae were better on 5% water agar than in distilled water, and at 26°C and pH 5.0. Germination occurred equally well at a light intensity below 100 lux or in the dark, and was better on water agar supplemented with leaf extract than on pure water agar. Water agar amended with triazole fungicides reduced conidial germination and hyphal growth significantly, in proportion to increasing fungicide concentrations, but the magnitude of reduction depended on the fungicides.