Capsicum & Chilli
Leveillula mostly affects the leaves while stalks and fruits are occasionally infected. The first symptoms are powdery, whitish spots on the underside of the leaves and yellow spots of varying intensity on the upper side. Later on, the whitish, powdery spots may also develop on the upper side. As the disease progresses, infected parts shrivel, leaves fall off and plants might die.
Fungal spores overwinter inside leaf buds and other plant debris. Wind, water and insects transmit the spores to nearby plants. Even though it is a fungus, powdery mildew can develop rather normally in dry conditions. It survives at temperatures between 10-12°C, but optimal conditions are found at 30°C. In contrast to downy mildew, small amounts of rainfall and regular morning dew accelerate the spreading of powdery mildew.
For gardens, milk-water solutions seem to work as natural fungicide. Apply this solution to the leaves every second day. The types of powdery mildew differ according to the host, and this solution may not be effective for all types. If no improvement is observed, try garlic or sodium bicarbonate solutions. Commercial biological treatments are also available.
Always consider an integrated approach with preventive measures together with biological treatments if available. Because a large number of crops are susceptible to powdery mildew, it is difficult to recommend a specific chemical treatment. Fungicides based on wettable sulphur, triflumizole, myclobutanil, seem to control the growth of the fungus in some crops.