fungal diseases, very large group of vine diseases which are caused by small, mostly microscopic, and filament-shaped organisms. Since fungi lack chlorophyll they need to live on other organisms to obtain nourishment. Fungal diseases have been of major significance in affecting grape production over centuries, with important consequences for both quantity and quality. Today they receive little public attention since they can successfully be controlled by a wide range of agricultural chemicals. In fact the famous fungicide bordeaux mixture was used commercially to control downy mildew in 1885 and for 50 years was the most important control of other fungal and bacterial plant diseases. Fungal disease epidemics are commonly related to weather conditions; examples are downy mildew and botrytis bunch rot, both of which are favoured by warm, wet or humid weather, while powdery mildew is favoured by overcast weather.