Powdery mildew
A white to greyish-white powdery coating on the upper side of leaves and shoots that partly wipes off. Leaves curl, yellow and shrivel; common on courgette, pumpkin, peas, roses, oak and apple.
The fungus thrives with warm days, cool nights and dry soil, especially in late summer.
What can you do?
- Cut off affected leaves and shoot tips as soon as you see the powder and put them in the green waste bin or general waste, not on your compost heap.
- Water at the base of the plant and keep the soil moist; drought makes plants more susceptible.
- Space plants well so air can move between them.
- On courgettes and pumpkins, some mildew at the end of summer is normal and needs no action.
Prevention
Choose resistant or less susceptible varieties, go easy on nitrogen and give plants enough space and sun.
When to watch out: June–September