Anthracnose causes light or purplish brown spots on the leaves. The spots may be very small at first but grow to an eighth inch in diameter. There may be a purplish border around the spots. No chemical control is listed.
Leaf spot causes brown spots with reddish borders. The spots have irregular shapes and are one-fourth inch in diameter. The lower leaves are most frequently attacked. A heavy infection causes death of the entire leaf. No chemical control is listed.
Root and stem rots of various sorts decay the roots and stems. Infected plants should be destroyed. No chemical control is listed.
Verticillium wilt kills plants occasionally. Avoid infested soil and destroy infected plants. No chemical control is listed.