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White powder on leaves: beating mildew organically
White powdery patches, fuzzy grey growth or black sooty film on your leaves? That’s mildew. Here’s how to stop it slowing — and eventually killing — your plants.
Mildew is a family of fungal diseases — powdery (white dusty patches), downy (fuzzy growth, usually on the underside) and sooty (a black film over honeydew left by sap-suckers). Left alone it slows growth and can eventually kill the plant. Cucumber, pumpkin, melons, beans and bhindi are frequent sufferers.
Mildew is far easier to prevent than to cure, and prevention is almost all about air and water: give plants room to breathe, keep their leaves dry, and step in early with a baking-soda or neem spray at the first white dusting. Sooty mould is a clue too — clear the aphids or mealybugs feeding above it and the sootiness fades on its own.
Improve airflow
Mildew loves still, humid, crowded conditions. Prune excess growth and space plants out so air moves freely — the cheapest, most effective fix there is.
Don’t over-water
Water the soil, not the leaves, and avoid wetting foliage in the evening. Dry leaves resist fungus.
Spray baking soda
One teaspoon of baking soda per litre of water (plus a drop of soap) makes the leaf surface alkaline and inhospitable to mildew. Test first to avoid scorch.
Use neem
A 10% neem oil spray helps control and prevent fungal spread. Repeat weekly while conditions stay humid.
Prevent the next round
Plant resistant varieties, disinfect your tools between plants, and remove and bin affected leaves so spores don’t spread.
Frequently asked questions
How do I get rid of powdery mildew naturally?
Improve airflow, keep leaves dry, and spray a baking-soda solution (1 tsp per litre + a drop of soap) or 10% neem oil. Remove and bin affected leaves.
What causes mildew on plants?
Fungus thriving in still, humid, crowded conditions — often made worse by overhead watering and over-crowding.
Which plants get mildew most?
Cucumber, pumpkin, melons, beans and bhindi (okra) are common sufferers.
What is sooty mould?
A black fungal film that grows on the sticky honeydew left by aphids, mealybugs or whiteflies. Clear the insects above and the sootiness clears too.