Symptoms
- check_circleYellow, pale green, or brown patches on upper leaf surfaces
- check_circleGreyish, purple, or white fuzzy growth on the underside of leaves
- check_circleLeaves wilting and dying in wet conditions
- check_circleRapid spread through a crop in cool, wet weather
Causes
- arrow_rightDamp conditions with temperatures between 10–15°C
- arrow_rightHigh humidity and poor air circulation
- arrow_rightOverhead watering and rain splash spreading spores
- arrow_rightInfected seedlings or plant material
How to Diagnose
The fuzzy growth on the undersides of leaves is the key identifier. Unlike powdery mildew, downy mildew prefers cool, wet conditions and does not rub off easily.
Treatment
Remove and destroy affected leaves and plants. Apply a copper-based fungicide. Improve ventilation and reduce humidity. Avoid overhead watering. There is no cure once severely infected — remove affected plants to prevent spread.
Prevention
Space plants adequately. Water at the base. Improve greenhouse ventilation. Choose resistant varieties. Rotate crops annually to prevent build-up of spores in soil.
starsPremium Diagnosis
Upload a photo for AI-powered diagnosis and a personalised treatment plan.
Try Premium Free