Seasonal development
and life cycle—Gray mold
Botrytis fruit rot occurs under cool, wet conditions. Physical damage to the plant increases disease
incidence, especially during the rainy season. The pathogen overwinters as sclerotia on infected canes
and sometimes as mycelium in infected tissues. Spores from overwintering structures and dead leaves and
mummified berries are the main sources of primary inoculum. Spores are dispersed by wind, rain, and overhead
irrigation. Flowers are not susceptible to infection until they have opened. Infections generally remain
dormant until fruit is nearly ripe, or after harvest. Infections can reoccur throughout the season by
sporulation of the fungus on unpicked, overripe fruit left on the vine. | 
Sclerotia
overwinter on canes
|
