The disease is favored by cool moist conditions and little or no wind. Cool, damp, poorly ventilated greenhouses are ideal for the disease, and Botrytis blights are probably the most common diseases of greenhouse-grown crops, especially in the spring and fall when the vents of greenhouses are closed at night to prevent heat loss. In the greenhouse, gray mold is often said to be a disease of bad management. Graymold losses in the field are severe following prolonged periods of overcast skies, fogs, heavy dews, or light drizzly rains.