Anthracnose fungi may cause defoliation of most maple, oak, elm, walnut, birch, sycamore, and hickory species and, occasionally, of ash and linden trees. Damage of this type usually occurs after unusually cool, wet weather during bud break. Single attacks are seldom harmful to the tree, but yearly infections will cause reduced growth and may predispose the tree to other stresses. Damage may be in the form of:
killing of buds, which stimulates the development of many short twigs or "witches' brooms;" these may spoil the shape of the tree
girdling and killing of small twigs, leaves, and branches up to an inch in diameter
repeated early loss of leaves, which over several successive years weakens the tree and predisposes it to borer attack and winter injury
premature leaf drop, which lessens the shade and ornamental value of the tree
Rake up and remove infected leaves in the fall. Leaves may be shredded and composted or burned.
Prune out and burn or bury dead twigs and small branches. Prune to thin the crown. Thinning will improve air movement and promote faster drying of the leaves.
If fertilizer is needed, fertilize in the fall about a month after the average date of the first frost or in early spring about a month before the date of the last frost to increase tree vigor.
If chemical control is desired, spray with a fungicide containing mancozeb (e.g. Manzate 200, Dithane M-45) at budswell and twice again during leaf expansion (in most years, this would be at 10-14 day intervals). Follow label rates.
Because Discula anthracnose is often fatal to the tree, control of this anthracnose disease on dogwood is a special case