Powdery mildew
What it is, what is looks like, and how to treat it
What it is
Powdery mildew is a fungal disease caused by a range of species, most commonly from groups such as Erysiphe, Oidium, and Podosphaera. It affects a wide variety of plants - from roses, delphiniums and dahlias, to courgettes, apples, and even oaks.
Unlike many fungal diseases, it doesn’t need soaking wet leaves to get started. In fact, it has a slightly rebellious streak and often thrives when other fungi don’t.
What it looks like
A fine white or grey powder on leaves, stems, buds, or flowers
Often starts as small circular patches
Leaves may curl, distort, or yellow
In severe cases, foliage can look dusty, stunted, and tired
It really does look like someone has sifted icing sugar over your plants - charming in a bakery, less so in a border.
