Powdery mildew is a fungal disease which flourishes on courgettes when the weather is warm and dry. Infected courgette plants are covered in a greyish-white mould, mainly on the upper surface of the leaves and young shoots.
CONTROL OF POWDERY MILDEW
* Attacks of powdery mildew occur in dry seasons and are worst in sheltered gardens. * It is not known how the fungus survives between crop seasons, & crop rotation and many other cultural practices seem to have little effect on the incidence of powdery mildew. * Courgettes need fertile soil. Plants grown in poor soil, without correct applications of fertiliser, will develop powdery mildew before well fed plants. Healthy, vigorous leaves and stems are less prone to infection. * Grow Mildew tolerant varieties of courgettes, such as Dundoo, Soleil
* Chemical sprays are available to control mildew. Always follow the instructions on the packet.