What is powdery mildew?

Powdery Mildew is a common fungal problem found on a number plants.

The fungus is cosmopolitan and found where ever conditions are favourable for development: damp foilage, poor air circulation, soft tissue or plants under stress. Development of the fungus can be prevented by remedial action to the above conditions or by applying a suitable fungicide. Normally copper-based fungicides are used for grapes.