Powdery mildew effects plants including apple, phlox, honeysuckle, peas and gooseberry. They are a group of related fungi, but each has a narrow host range – for example a powdery mildew on roses will not spread to peas.
There is no fungicide for this so management requires planning.
Powdery mildew builds up over the growing season.
Can effect squashes in late summer.
Manage by clearing up infected leaves – do not compost these.
Encourage good air circulation in growing patches.
Avoid too much nitrogen fertiliser.
Prune out infected areas in fruiting trees – eg apples.