Grey mold

Botryotinia fuckeliana (teleomorph of Botrytis cinerea) is a devastating fungal pathogen responsible for grey mold, a disease that affects a vast range of horticultural and agricultural crops. Classified within the order Helotiales, it is a necrotrophic fungus, meaning it kills plant tissues to derive nutrients, resulting in significant yield losses worldwide.

The disease is characterized by the appearance of dense, greyish fuzzy masses on the surface of leaves, fruits, and flowers, which are the fungal conidia (spores). Infected tissues quickly collapse into a soft rot. On grapes, it causes substantial economic damage by rotting berries, significantly impacting the quality of the harvest and the potential for wine production.

The life cycle is complex and involves the production of sclerotia—hard, dark structures that serve as survival units in the soil or decaying plant debris. When environmental conditions become favorable, these sclerotia germinate to produce conidiophores and conidia. These spores are then dispersed by air currents, splashing rain, or contact with agricultural tools, facilitating rapid spread across fields.

Environmental conditions are critical for the development of Botryotinia fuckeliana. High humidity, mild temperatures, and the presence of free water on plant surfaces are ideal for spore germination and colonization. The fungus is especially aggressive when plants are weakened, stressed, or possess physiological wounds, such as those caused by insects or harvesting equipment.

Integrated pest management (IPM) is the most effective approach to control grey mold. This includes cultural practices such as improving air circulation, pruning to remove infected debris, and balancing nutrient applications to prevent lush, susceptible growth. In intensive production systems, the strategic application of fungicides, particularly during the flowering and fruit ripening stages, is essential for maintaining crop health.