Surface application of ammonium nitrate fertilizer at the rate of 18 pounds per 1,000 square feet, or of urea at 13 pounds per 1,000 square feet, is recommended. Resistant tree varieties should be used whenever possible. Various fungicides can be used to control anthracnose on valuable trees, but chemicals rarely control this disease completely. Spraying can protect leaves from infection but it will not prevent the development of cankers on sycamores and oaks in which the fungus overwintered within the tree. Apply a suggested fungicide two or three times, at 14-day intervals, starting at leaf emergence.
Thorough coverage is required.
The manufacturer's directions should be carefully followed. Spraying after the disease is evident will only protect healthy new leaves. Back to Top Table 1 . Trees weakened by repeated infection may become unsightly. Birch Small to large, round to irregular, light brown to dark brown lesions with yellow margins form on the leaves.