Grape diseases

species of fungus

right|thumb|A grape cluster with signs of millerandage with small, immature berries scattered throughout the bunch. Millerandage (or shot berries, hens and chicks and pumpkins and peas) is a potential viticultural hazard in which grape bunches contain berries that differ greatly in size and, most importantly, maturity. Its most common cause is cold, rainy or otherwise bad weather during the flowering stage of the vines though other factors, such as boron deficiency or fanleaf degeneration, may also play a role.

right|thumb|Young grapes are most susceptible to coulure right after flowering when they need vital carbohydrate resources in order to develop fully. Coulure (pronounced coo-LYUR) is a viticultural hazard that is the result of metabolic reactions to weather conditions that causes a failure of grapes to develop after flowering. In English the word shatter is sometimes used. Coulure is triggered by periods of cold, cloudy, rainy weather or very high out-of-season temperatures. The condition is most often manifested in the spring. It also occurs in vines that have little sugar content in their ti