Powdery Mildew Control — Identification, Treatment & Prevention
Powdery mildew is a fungal disease characterised by white powdery patches on leaves and stems. Unlike most fungal diseases, it thrives in dry weather with cool nights. Early fungicide application prevents major crop loss.
How to identify powdery mildew
Watch for these signs in your field.
White powdery coating on leaves
White to grey powdery fungal growth on the upper surface of young leaves. In severe cases, entire leaves are covered, turning yellow and dying.
Distorted young shoots
New growth appears twisted and stunted. Severely infected shoot tips die back (tip dieback), particularly in grapes and cucurbits.
Affected fruits and berries
In grapes, berries split or crack and may develop russeting. In cucurbits, fruit quality and size are significantly reduced.
How to control powdery mildew
Follow this step-by-step protocol for best results.
Apply sulfur or tebuconazole at first sign
Wettable Sulfur 80% WP (2–3 g/L) is the most cost-effective preventive fungicide for powdery mildew. For curative action, use Tebuconazole 25.9% EC (0.5 ml/L) or Hexaconazole 5% EC (1.5 ml/L).
Do not spray sulfur in high temperatures
Sulfur is phytotoxic above 38°C — do not apply on hot days. Switch to systemic triazole fungicides (Propiconazole, Tebuconazole) during summer months.
Ensure good air circulation
Proper canopy management, pruning, and plant spacing improve air circulation and reduce humidity inside the canopy. This reduces the spread of powdery mildew significantly.
Which crops are at risk?
Tap a crop for the full pest management guide.
Powdery Mildew — Common Questions
Why does powdery mildew spread in dry weather?
Unlike most fungal diseases, powdery mildew does not need free water to germinate — its spores germinate in high humidity (70–80% RH) with cool nights and dry days (20–28°C). This explains why it thrives in autumn and winter in India rather than in the rainy season.
Which fungicide is best for powdery mildew on grapes?
Wettable Sulfur 80% WP (2.5 g/L) is the first choice for powdery mildew on grapes — it is also a recommended organic option. For systemic control, use Myclobutanil 10% WP (1 g/L) or Penconazole 10% EC (0.5 ml/L). Spray every 10–14 days from early shoot growth.
How to prevent powdery mildew in cucurbits (cucumber, gourd, melon)?
Apply Mancozeb 75% WP (2 g/L) preventively from 15 days after transplanting, every 10–12 days. At first sign of white patches, switch to Tebuconazole 25.9% EC (0.5 ml/L). Avoid overhead irrigation and ensure proper spacing for air movement.
Still struggling with powdery mildew?
Describe your situation to our certified agronomists — they will recommend the right treatment for your crop and region, free within 24 hours.
Get Free Expert Advice