Powdery mildew (Podosphaera spp., Sphaerotheca spp., Erysiphe spp.)Powdery mildew is a collective name for a group of fungi that infect a very wide variety of plants - a single species only infects a limited number of crops. It tends to occur when the air is damp but the soil is dry. The whole plant is weakened and leaves and flowers may wither and drop, or growth may be distorted.
- Almost any part can be affected with a white powdery coating which may spread
- Upper surfaces of leaves are often particularly affected.
- In gooseberries (American Gooseberry Mildew, Sphaerotheca mors-uvae), the fruit are covered with a brown furry coating, which becomes a bit like felt with age. However, the fruit beneath are still edible if it is scraped off.
Prevention & control
- Resistant varieties of many crops are available
- Avoid using too much nitorgenous fertiliser which causes lush, susceptible growth
- Keep plants well watered at the roots
- Ensure good air circulation, in gooseberrys and currants, pruning out out the middle of bushes
- Good plot hygiene, removing all traces of previous crops, gives the fungus fewer places to lie dormant over winter.
- Pick off and burn infected leaves
- In severe cases, it can be controlled with a sulphur spray.
Courgette, sum. squash
Pumpkin, wint. squash
Currant, red and white