Leaf symptoms of oak anthracnose.
Oak anthracnose is caused by the fungus Gnomonia veneta. Trees of the white oak group, particularly white oak, are susceptible to this disease. Oaks throughout the entire eastern United States are affected by the disease, although it is less common in the Northeast.
Infection occurs in the early spring or mid-summer. Symptoms on leaves develop as irregular brown diseased areas (blotches) along the midrib and the major side veins. These blotches may grow together by late spring or early summer if infection occurs early. Blotches are usually confined to the areas bordered by the larger veins. Leaves on the lower branches are frequently killed and occasionally trees will be defoliated. However, a second crop of leaves soon develops and mortality is rare. Fruiting bodies of Gloeosporium, the imperfect fungus fruiting stage of anthracnose, are located on the midrib and veins of infected leaves. When the disease spreads to the twigs, cankers and crown dieback may occur. The anthracnose fungus overwinters on diseased twigs and in the leaf litter. Oak anthracnose has the same causal agent as sycamore anthracnose, and the weather conditions favoring the sycamore disease also increases the anthracnose on oak.
Control is similar to sycamore anthracnose and involves an integrated program of pruning disease tissue, fertilization, and burning of leaf litter. No practical control is available for forest trees.
DOGWOOD ANTHRACNOSE
Dogwood anthracnose, caused by the fungus Elsinoe corni, occurs in states bordering the Atlantic Ocean and has also been reported in Louisiana. Its primary host is flowering dogwood, Cornus florida L.
Leaf and flower symptoms of dogwood anthracnose.
