The black oak is a medium-to-large, deciduous tree that can reach mature heights up to 80 feet. This slow-growing shade tree develops nearly black outer bark that protects a yellowish-orange inner bark. The tree produces a showy display of rich green foliage with yellow, pendulous spring flowers. Like other oak varieties, the black oak tree is susceptible to several diseases that can be detrimental, if not fatal, to the tree's health.
Oak wilt is a fatal fungal disease for the black oak tree. This vascular disease infects the tree through its root system using fungal spores. Spores infect the fine, fibrous vessels of the tree's vascular system, preventing nutrients and water from traveling throughout the tree. Infected trees experience severe foliage discoloration and wilting over several weeks. Trees with oak wilt also lose many of their leaves and develop a black streak through their sapwood. Infected black oaks can cross-contaminate surrounding trees through the release of fungal spores into the air and by underground, root-to-root contact with other trees. There is no cure or treatment for oak wilt. Infected trees should be removed and destroyed, according to Iowa State University Extension.
Slime flux is a bacterial disease that is commonly referred to as "wetwood." This foul-smelling disease infects the black oak tree through any wounds and weakened areas, attacking its woody central core. The infected wood becomes discolored and develops a water-soaked appearance. The water-soaked areas begin to ooze a bacterial slime that is accompanied by a gaseous foul smell. As the ooze dries, it turns from a light yellow color to a grayish-colored crust. Although slime flux does not kill the black oak, it stunts its growth and causes some dieback in the tree. Surrounding foliage and grass can also be killed by the toxic ooze from the tree. While there is no cure or chemical treatment available for slime flux, it can be controlled by removing the infected areas and maintaining an adequate fertilization schedule, according to University of Colorado Cooperative Extension.
Oak anthracnose is foliage fungal disease that is disfiguring, but not fatal, to the black oak tree. This fungal disease develops in tree debris that lies around the black oak tree. During the wet and warm spring months, the fungal spores are transported on the foliage of the black oak by wind and rain. This fungus then infects the foliage of the tree with symptoms appearing mostly towards the bottom of the tree, according to University of Minnesota Cooperative Extension. Infected black oak trees develop random spots and blotches on its leaves. Infected foliage also experiences curling and discoloration. The disease is less invasive if the tree is otherwise healthy. To avoid and control the disease, fertilize the tree regularly to keep it growing vigorously. Severely infected trees can be treated with a series of cooper-based fungicidal sprays.