Disease Stressors

Many diseases occur in southern forests. Disease introduction and outbreak is an ever-changing cycle to which all landowners should try to educate themselves.  Current U.S. regulations prevent entry only of pests that are (1) not present in the United States; or (2) present, but of limited distribution, and subject to an active eradication/control program.  To be effective, inspectors must be able to find and identify new invaders before they enter and become established. Unfortunately, the necessary taxonomic information does not always exist.

Many forest diseases are native and a natural part of the ecosystem. Diseases can help to keep the forest healthy by removing weak or injured trees. They also can improve wildlife habitat by creating holes in trees and snags. However, some exotic diseases have been devastating to the ecosystem. These diseases are not native to the ecosystem and thus can spread unchecked, killing many trees and threatening the health of southern forests. The biology, symptoms, spread, and management of these important diseases are outlined here.

Of the several types of forest stressors highlighted in the South-wide encyclopedia, including insects, exotic and invasive plant species, and a host of abiotic stressors, certain diseases have earned both historical and environmental infamy even to the casual observer. Chestnut blight and Dutch elm disease highly impacted the lives of Americans from forests to street corners. However, there are many more diseases possibly poised to create similar impacts, such as sudden oak death.  It is important to evaluate as many forest disease stressors as possible to arm ourselves with knowledge.

In this section, more than sixteen disease stressors from both coniferous and hardwood forests are examined with more depth of information. Coniferous forests diseases include fusiform rust, annosus root disease, brown spot needle, littleleaf disease, and pitch cankers. Deciduous forests diseases include dogwood anthracnose, beech bark disease, butternut canker, chestnut blight, and Dutch elm disease.  Three diseases associated with oaks are also presented, including oak wilt, oak decline, and sudden oak death.  Finally, some generalized diseases, such as plantation diseases, root and butt rot, and wood decay fungi, are discussed.