Fungicide chemical classes for powdery mildew management
Managing powdery mildew requires understanding the distinct biochemical modes of action available in registered agricultural fungicides.
Rotating chemistries across different FRAC groups prevents the rapid development of fungal resistance in intensive horticultural crops.
- Inorganic Sulphur (Multi-site): Wettable Sulphur (80% WDG/WP) providing contact multi-site protection and acaricidal mite suppression.
- Triazoles / DMIs (FRAC Group 3): Systemic fungicides like Hexaconazole, Tebuconazole, and Difenoconazole providing protective and curative kickback.
- Strobilurins / QoIs (FRAC Group 11): Protectants like Azoxystrobin and Pyraclostrobin inhibiting mitochondrial respiration and spore germination.
- SDHIs (FRAC Group 7): Advanced carboxamides like Fluopyram and Fluxapyroxad offering translaminar penetration and long residual control.
Target crops and approved fungicide options
Powdery mildew attacks diverse agricultural and horticultural crops, especially during warm, dry days coupled with humid, cool nights.
Selecting the right formulation depends on the specific crop growth stage, temperature sensitivity, and disease severity.
- Grapes: Uncinula necator controlled with Wettable Sulphur early season, followed by Triazoles and SDHIs during berry development.
- Mango: Oidium mangiferae attacking flower panicles; controlled with Triazoles or Wettable Sulphur before full blossom opening.
- Chilli: Leveillula taurica (internal powdery mildew); requires penetrating systemic fungicides like Tebuconazole or Kresoxim-methyl.
- Pulses (Pea, Blackgram): Erysiphe polygoni; managed with early foliar applications of Wettable Sulphur or Hexaconazole.
Application timing, biological alternatives, and safety
Initiate spraying preventively before powdery white patches cover more than 5% of foliage, ensuring thorough upper and lower leaf wetting.
Biological agents like Ampelomyces quisqualis and neem-based formulations provide effective eco-friendly suppression in organic farming systems.
- Preventive timing: Apply upon receiving weather warnings for dry sunny days with cool humid nights.
- Sulphur temperature precaution: Avoid spraying wettable sulphur when ambient temperatures exceed 35°C to prevent severe leaf scorching.
- Protective measures: Wear protective overalls, rubber gloves, and face shield; respect statutory pre-harvest intervals.
Official source
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Central Insecticides Board & Registration Committee ↗Related on KisanPe
Common questions
What are the most effective fungicides for powdery mildew?
Wettable Sulphur (contact multi-site), Triazoles (Hexaconazole, Tebuconazole), and SDHIs (Fluopyram) are highly effective.
Can Wettable Sulphur be sprayed during hot summer weather?
No, avoid spraying sulphur when temperatures exceed 35°C, as it can vaporize too quickly and cause severe phytotoxic leaf scorching.
How does powdery mildew damage crops?
It forms white superficial mycelial mats that block sunlight, extract nutrients via haustoria, cause leaf curling, flower drop, and fruit russeting.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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