Wheat Powdery Mildew Control

Symptoms

White to greyish powdery patches appear first on the upper surface of the lower leaves and on leaf sheaths, looking as if flour or talcum powder has been dusted on the crop. The patches enlarge and may cover much of the leaf, later turning dull grey with tiny black dots. Affected leaves yellow and dry early. The disease is favoured by cool, cloudy, humid weather and dense shaded crops.

Damage

Powdery mildew reduces green leaf area and photosynthesis, weakens the plant and causes poor grain filling and shrivelled grains, with yield losses commonly of 10 to 20 percent and higher on susceptible varieties in cool humid seasons. It is more common in the cooler northern hills and irrigated areas with dense crops.

Organic & cultural control

Grow resistant varieties where available and avoid very dense sowing and excess nitrogen which create the shaded humid canopy the fungus likes. Ensure good spacing and airflow, use balanced fertiliser, and remove heavily infected lower leaves where practical. A spray of wettable sulphur is a traditional and effective option against powdery mildew on cereals.

Chemical control

If the disease spreads on the upper leaves, spray a registered fungicide such as wettable sulphur, or a systemic option like propiconazole 25 EC, with good coverage and repeating as per label if needed. Always follow the product label dose, observe the pre harvest interval and consult your KVK or agronomist before spraying.

Always follow the product label, the recommended pre-harvest interval, and your local KVK or agronomist. Pesticide approvals change, so verify before use.

Prevention

Use resistant varieties, sow at the recommended seed rate and spacing to avoid a dense crop, and keep nitrogen balanced. Ensure good drainage and airflow and follow field sanitation. In cool humid pockets prone to the disease, monitor the lower leaves from tillering and act early before the mildew reaches the flag leaf.