One fungal disease of vegetable plants and some fruit trees which is debilitating is powdery mildew. It affects the foliage and stems by covering them with patches of white mould (mold). In the worst cases, those leaves end up distorted, swollen and eventually dying.
The worst affected plants are gooseberries and blackcurrants (most Ribes in fact), grapes, courgettes, marrows and all members of the Rosaceae family. Different strains attack different crops so there are variations in the level of damage. Just look for cultivars and varieties which show resistance to this problematic mold.
Reducing the Level Of Infection
The best way to keep the level of infection down, and by the way, it can never be fully eradicated, is to water well especially during times of dryness. Always mulch well around the crop as this provides a barrier to dryness and keeps up humidity levels.
destroy any affected foliage as soon as possible because once it take hold, it soon spreads rapidly. Fungicides can be used because it treats the leaf surface. This specific targeting means other parts of the plant especially the fruit are kept fungicide free during spraying.
Look out for mildew resistant crops, there are varieties which are capable of resisting the onslaught of this problem fungus.