Botrytis Gray Mold
Botrytis cinerea
Overview
A ubiquitous fungal disease that attacks flowers, fruits, leaves, and stems, producing characteristic fuzzy gray mold. It is especially damaging in cool, humid conditions and on overripe or damaged tissue. Botrytis Gray Mold spreads mainly by spores on wind, splash, tools, and crop debris. Humid, crowded plantings and overhead watering favor outbreaks in home gardens and food forests. Causal agent: Botrytis cinerea. In regenerative gardens, prioritize sanitation, airflow, and unbroken soil cover over calendar spraying, and intervene early when symptoms appear.
Symptoms
Fuzzy gray-brown mold on flowers, fruit, leaves, and stems. Water-soaked lesions that quickly become covered with gray sporulation. Flower petals turn brown and papery. Fruit develops soft, watery rot. Compare several plants and note whether symptoms spread after rain, insect feeding, or wet foliage. Photograph undersides of leaves and cut stems when wilt is present to refine the diagnosis. Rule out simple drought, fertilizer burn, and herbicide drift before assuming a pathogen - abiotic injury often mimics disease.
Environmental Conditions
Cool
Prevention
Ensure excellent air circulation. Avoid overhead watering. Remove dead flowers and plant debris promptly. Space plants adequately. Reduce nitrogen fertilization to avoid lush, susceptible growth. Mulch to reduce splash, clear season-end debris, and avoid working plants when wet. Design beds for airflow and diverse plantings that support beneficial insects without creating permanent humid pockets around susceptible crops.
Management
Remove infected plant parts immediately. Apply biological controls like Bacillus subtilis or Trichoderma. Copper or sulfur sprays can help. Ensure good ventilation in greenhouses. Avoid wounding plants. Prefer drip irrigation, morning watering, and open spacing so leaves dry quickly. Disinfect pruners between cuts on woody plants. Use copper, sulfur, or biological products only as labeled protectants when pressure is high - they rarely reverse advanced infections alone. Destroy (do not casually compost) highly infectious debris.