Graufäule

Graufäule is a term used in German horticulture to describe a disease complex that causes rotting of various plant tissues, typically accompanied by a gray, fuzzy mold on infected material. The name is most closely associated with gray mold caused by Botrytis cinerea, a widespread ascomycete fungus, though other Botrytis species can be involved depending on the host and region.

Symptoms and hosts: On fruit such as grapes, strawberries, apples, pears, and berries, Graufäule often begins as small water-soaked lesions that later develop a dense gray mold covering the surface. In grapes, it can manifest as botrytis bunch rot, reducing yield and quality. On flowers, leaves, and vegetable crops, a similar fuzzy gray growth may appear, with tissue collapse occurring in severe cases.

Environment and disease cycle: Development requires high humidity and moist conditions, with temperatures generally between 15 and 25 C. The pathogen overwinters in plant debris as resistant structures (sclerotia) and produces wind-dispersed conidia that infect wounds or damaged tissue, facilitating spread under favorable weather.

Management: Prevention relies on sanitation (removing infected material), maintaining good air circulation through pruning and canopy management, and avoiding overhead irrigation. Implement integrated crop protection strategies appropriate to the crop and region, including resistant varieties where available and, when necessary, fungicide applications according to local guidelines.

Etymology: Graufäule derives from grau (gray) and Fäule (rot), describing the characteristic gray rotting appearance of the disease.