Maple

From Bugwoodwiki

USDA Forest Service. 1979. A guide to common insects and diseases of forest trees in the northeastern United States. Northeast. Area State Priv. For., For. Insect and Disease Management., Broomall, PA. p. 123, illus.

Maple anthracnose, caused by Gloeosporium apocryptum, is confined to Norway maple, sugar maple, and Japanese red maple. When conditions are wet enough, the disease can kill a great number of leaves and even entire trees.

Purple-to-brown dead areas appear along the veins of infected Norway maple leaves. On sugar maple leaves, large, irregular green-brown or red-brown dead areas form along and between the veins and extend out to the edges of the leaves. On Japanese red maple, irregular light- to dark-brown dead areas form at the base of the leaves.

Symptoms of anthracnose in sugar maple may be confused with symptoms of leaf scorch, a condition resulting from drought and heat injury, but with anthracnose, small, brown fruiting bodies form along the veins of leaves. Fruiting bodies of the fungus on Norway maple are also brown, while those found on Japanese red maple are dark brown to black. The fungus overwinters primarily in fallen leaves.