Gray mold, also known as gray rot, is a common fungal disease affecting strawberries caused by the pathogen Botrytis cinerea. It can cause significant damage to both fruit and foliage, leading to reduced yield and quality. Here’s an overview of its symptoms, recommendations, causes, and preventive measures:

Symptoms:

1. Fruit Symptoms:
   • Grayish-brown, fuzzy fungal growth on ripe or overripe strawberries, usually starting from the calyx end.
   • Soft, water-soaked lesions on the fruit surface that quickly develop into moldy patches.
   • Infected fruit may become mushy, collapse, and emit a foul odor.
   • Fruit may remain attached to the plant or drop prematurely.
2. Foliage Symptoms:
   • Grayish-brown lesions on leaves, stems, and flowers, particularly under humid conditions.
   • Lesions may expand rapidly, leading to blighting and dieback of affected plant parts.

Recommendations:

1. Cultural Practices:
   • Plant spacing: Maintain proper spacing between strawberry plants to promote air circulation and reduce humidity, which can help minimize disease development.
   • Weed control: Keep the area around strawberry plants free from weeds to improve air movement and reduce the risk of fungal spore accumulation.
   • Mulching: Apply mulch around strawberry plants to prevent soil splash onto foliage, which can reduce the spread of Botrytis spores.
   • Avoid overhead irrigation: Water strawberry plants at the base to keep foliage dry and minimize the risk of disease spread.
2. Harvesting Practices:
   • Harvest ripe strawberries promptly to reduce the risk of Botrytis infection. Remove and discard any rotten or overripe fruit.
   • Handle harvested fruit carefully to minimize bruising and damage, which can provide entry points for fungal infection.
3. Fungicidal Control:
   • Apply fungicides labeled for use against gray mold according to recommended schedules, particularly during periods of high disease pressure.
   • Rotate between fungicide groups with different modes of action to reduce the risk of resistance development in Botrytis populations.

Causes:

1. Fungal Pathogen: Gray mold of strawberries is caused by the fungus Botrytis cinerea.
2. Environmental Conditions: Botrytis cinerea thrives in cool, humid conditions. Rain, dew, and high humidity create favorable conditions for spore germination and disease development.
3. Injury and Wounds: Bruising, crushing, or other injuries to strawberry fruit or foliage provide entry points for Botrytis infection.

Preventive Measures:

1. Sanitation: Remove and destroy infected plant debris, including rotten fruit and affected plant parts, to reduce the source of inoculum for future infections.
2. Air Circulation: Prune strawberry plants to improve air circulation within the canopy and reduce humidity around plants.
3. Resistant Varieties: Select strawberry varieties that are resistant or less susceptible to gray mold, if available.
4. Integrated Pest Management (IPM): Implement an IPM approach that combines cultural practices, fungicidal control, and resistant varieties to effectively manage gray mold while minimizing environmental impact.

By implementing these preventive measures and adopting an integrated approach to disease management, strawberry growers can minimize the impact of gray mold and maintain healthy strawberry production.