Strawberry powdery mildew, caused by the fungus Podosphaera aphanis, is a common fungal disease that affects strawberry plants, particularly in humid conditions. It is easily identified by the characteristic white, fuzzy fungal growth on the plant’s leaves and other surfaces.

Symptoms:

• The disease is most recognizable by fuzzy white fungal growth that appears primarily on the lower leaf surfaces.
• In severe infections, small black fruiting bodies called cleistothecia may form on the undersides of infected leaves.
• A common symptom is leaf cupping, where the margins of infected leaves curl upward and inward.
• In some strawberry cultivars, red or purple/brown patches may develop on one or both leaf surfaces, which can resemble other leaf spot diseases.
• The fungus may also infect flowers and fruit, particularly those in dense canopy areas, as well as the upper leaf surfaces in plants grown in tunnels or greenhouses.

Favorable Conditions for Disease Development:

• Powdery mildew thrives in mild temperatures between 15°C and 25°C and in high relative humidity ranging from 75% to 98%.
• Rapid vegetative growth further encourages fungal development. However, the disease is suppressed by high temperatures, strong sunlight, heavy rains, and wet leaf surfaces.

Powdery mildew can damage strawberry plants, especially under mild, humid conditions. Early identification and managing environmental factors like humidity and plant canopy density can help in controlling the spread of the disease, ensuring healthy plants and fruit production.