Hyaloperonospora parasitica

Fungal Disease

Hyaloperonospora parasitica

Fungal Disease

Downy mildew is a destructive fungal-like (oomycete) disease affecting cauliflower from the seedling to the harvest stage. It thrives in cool, moist conditions and high humidity. The disease is characterized by yellowish leaf spots and white fluffy growth on the underside of leaves. Severe infections can damage cauliflower curds, leading to black spots and yield loss.

Symptoms of Downy Mildew

Leaves:Yellowish, irregular areas on the upper surface.White, fluffy growth on the underside

Older lesions turn dry, brown, and papery. Defoliation in severe cases

Cauliflower Curds:Black spots on or within the curds

Causes and Spread

Temperature: Thrives at 10–15°C , but can grow between 15–25°C 

Humidity: Requires relative humidity above 85%, with 90% needed for sporulation

Water: Infection occurs within three hours of spore contact on wet leaves

Spread: Windborne spores and water splash

Survival: Can persist in crop debris, soil, or brassica weeds for months

Prevention and Control

Resistant Varieties: Use downy mildew-resistant cauliflower varieties

Crop Rotation: Avoid continuous brassica cropping

Sanitation: Remove and destroy infected crop debris

Water Management: Avoid overhead irrigation to reduce leaf wetness

Spacing: Maintain proper plant spacing to improve air circulation

Fungicide Application: Apply appropriate fungicides as a preventive measure during favorable conditions

Managing downy mildew requires preventive practices and vigilant monitoring. By maintaining hygiene, optimizing irrigation practices, and using resistant varieties, farmers can minimize the disease's impact and ensure better cauliflower yields.