Anthracnose causes circular, depressed, dark colored spots which can be up to an inch in diameter. The spots are bordered by a raised ring and may run together and destroy the whole leaf. Remove and destroy infected leaves. No chemical control is listed.
Symptoms of leaf spot are zoned, light gray spots up to an inch or more in diameter. The spots have concentric rings in which black pimple-like fruiting bodies form. Large portions of leaves may be destroyed. Remove and destroy infected leaves. No chemical control is listed.
Leaf blight can destroy the leaves of overwatered or chilled plants. No chemical control is listed.