Lime (linden) powdery mildew

Symptoms

A thin, white to greyish powdery coating develops on the upper (and sometimes lower) surface of the heart-shaped leaves, often starting as discrete circular patches on young foliage and shoot tips in mid- to late summer. Affected leaves may be slightly distorted, cupped or stunted, and a faint chlorotic mottling can show through the fungal film; heavily colonised young leaves can yellow and drop early. By late season tiny pinhead-sized fruiting bodies (cleistothecia) appear as amber-to-black specks scattered in the white mat. Mature trees usually tolerate the infection with cosmetic leaf coating, while nursery stock, suckers and water-shoots are the most heavily affected.