Gooseberry mildew is a fungal disease that causes a white or brownish deposit on the leaves, shoots and fruit of gooseberries, and it also attacks the leaves and shoots of currants, but does not affect the fruit. It sometimes attacks flowering currants. The bushes can be seriously weakened in a bad attack.
Prune surplus shoots of gooseberries to keep the centre of the bush open, allowing air to circulate. The fungus mostly affects fruit at the centre of the gooseberry bush. The affected fruit can be wiped clean with a dry cloth and is perfectly good to use.
Prune out any affected shoots in summer, on both gooseberries and currants. In areas of persistent attack, to prevent fruit mildew, spray gooseberries with Systemic Fungicide when the first flowers open, and again when the fruit is the size of a pea.