VIEW ARTICLE

Ecology and Epidemiology

The Effects of Wind Speed, Temperature, and Relative Humidity on Development of Aerial Mycelium and Conidia of Botrytis cinerea on Grape. C. S. Thomas, Department of Plant Pathology, University of California, Davis 95616; J. J. Marois, and J. T. English. Department of Plant Pathology, University of California, Davis 95616. Phytopathology 78:260-265. Accepted for publication 19 August 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-260.

Development of aerial mycelium and conidia of Botrytis cinerea on surfaces of infected grape berries was evaluated under conditions of controlled wind speed, temperature, and relative humidity. Inoculated berries were incubated under three wind speeds (0, 0.3, and 0.6 m/sec). three relative humidities (69, 90, and 94%), and four temperatures (16, 21, 26, and 30 C) in a complete factorial design. Numbers of berries with aerial mycelium were determined daily for 6 days. Numbers of conidia produced per berry also were determined. Aerial mycelium developed most quickly at 21 C, 94% relative humidity, and 0 m/sec wind speed. Aerial mycelium did not develop on berries exposed to 69% relative humidity and wind. The greatest number of conidia were produced at 21 C, 94% relative humidity, and 0.6 m/sec wind speed. An estimate of evaporative potential of the air was made for each combination of wind speed, temperature, and relative humidity. Aerial mycelium and conidia developed if evaporative potential was below a threshold level that was related to temperature. Similar results were obtained under field conditions. Within the ranges tested, wind speed and relative humidity had a greater effect on evaporative potential than did temperature.