Diseases

Thousand cankers disease (Geosmithia morbida) is a newly recognized disease of black walnuts. It gets its name from the large numbers of small cankers on the branches and stems that eventually coalesce and result in necrosis of bark tissue. It is vectored by the walnut twig beetle (Pityophthorus juglandis).

Hypoxylon Canker (Hypoxylon spp.) is a secondary disease that affects trees that are already stressed by some other cause. Symptoms include delayed bud break, undersized leaves, wilted foliage and branch dieback. Signs include large spore-bearing mats visible after the bark has sloughed off.

Armillaria root rot is a general name for a group of diseases caused by fungi from the genus Armillaria. These are pathogens of roots and lower stems of both hardwoods and pines and are decomposers of wood. Signs include honey colored mushrooms at the base of the tree and black 'shoestring' rhizomorphs under the bark of infected trees.

Laurel wilt is a fungus (Raffaelea lauricola) that is vectored by the redbay ambrosia beetle (Xyleborus glabratus). It is spreads very quickly and kills plants from the Lauraeae family (redbay, sassafras, avocado) as well as a few other susceptible species. Symptoms are similar to those caused by drought.

Bacterial leaf scorch is a bacterial infection caused by the bacteria Xylella fastidiosa. Bacteria are vectored by insects and can infect hundreds of known hosts. Symptoms often resemble other vascular diseases, declines or abiotic stresses such as drought.

Fusiform rust (Cronartium quercum F. sp. Fusiforme) is a very common and potentially serious disease of slash and loblolly pine. The disease causes galls on stems which deforms trees, reduce growth, and weaken wood making trees more susceptible to breakage or bark beetle attack.

Pitch canker is caused by a fungus that creates a resin-soaked lesion in the inner bark and outer sapwood of southern pine species. Most often a nuisance, the disease can deform trees, suppress growth, and kill branches or occasionally entire trees. Contrary to popular belief, the pitch canker fungus is not carried or transmitted by insects; rather the fungus infects trees through wounds including but not limited to insect feeding sites.

Anthracnose is a general term for a group of diseases on hardwoods that cause lesions on leaves, twigs, and fruits. There are many species of fungi that cause anthracnose and can infect one or a few specific hosts.

Annosus root rot or Heterobasidion root disease is a serious disease in pine plantations that have recently been thinned. The fungus (Heterobasidion annosum) infects freshly cut stumps and spreads to living trees through root grafts which then makes those trees highly susceptible to wind-throw.

Seiridium canker is caused by Seiridium unicorne and can affect Leyland cypress trees of all sizes. Cankers may form on stems or branches and cause stem dieback. Spores from infected trees spread by water splash, unsanitized pruning tools or infected cuttings or plants.

Dutch elm disease is a vascular wilt of elms cause by a fungus Ophiostoma ulmi and Ophiostoma novo-ulmi. It is transmitted through bark beetles and root grafts and symptoms include branch 'flagging': wilted leaves that turn yellow to reddish brown and die.

Oak decline is a disease complex with many contributing stress agents and no single agent as a dominant role. It is a combination of biotic and abiotic stress agents such as drought, insect infestation, late frost, soil compaction, root damage, poor site, and mechanical injury.

Phytophthora root rot is a general name for a group of diseases cause by the fungi species Phytophthora. The pathogen attacks the roots of many trees and shrubs including azalea, rhododendron, dogwood, juniper, Fraser fir, white pine and others. Symptoms resemble those caused by nutrient deficiency, drought or decline.