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An Index of Common Tree Diseases

The Major Disease of Trees in the United States


There are over 20 common tree diseases that contribute to health decline and death of most of the trees in the United States. This list of tree diseases cause most tree health problems and death. These diseases are the cause of significant replacement expense of yard trees and the commercial expense of future losses of forest products.

1. American Chestnut Blight

American Chestnut Blight
Chestnut blight is a fungus that has virtually wiped out the American chestnut, as a commercial species, from eastern hardwood forests. Although roots from trees cut or killed many years ago continue to produce sprouts that survive to the sapling stage before being killed, there is no indication that a cure for this disease will be found. The fungus is widespread and continues to survive as a nonlethal parasite on chinkapin, Spanish chestnut, and post oak.

2. Amillaria Root Rot

Amillaria Root Rot
The disease attacks hardwoods and softwoods and kills shrubs, vines, and forbs in every state. It is pervasive in North America, commercially destructive, a major cause of oak decline. The Armillaria sp. can kill trees that are already weakened by competition, other pests, or climatic factors. The fungi also infect healthy trees, either killing them outright or predisposing them to attacks by other fungi or insects.

3. Anthracnose and Leaf Spot Diseases

USFS, FIDL Leaflet 133
Anthracnose diseases of hardwood trees are widespread throughout the Eastern United States. The most common symptom of this group of diseases is dead areas or blotches on the leaves. The diseases are particularly severe on American sycamore, the white oak group, black walnut and dogwood. The greatest impact of anthracnose is in the urban environment. Reduction of property values result from the decline or death of shade trees.

4. Annosus Root Rot

Annosus Root Rot
The disease is a rot of conifers in many temperate parts of the world. The decay, called annosus root rot, often kills conifers. It occurs over much of the Eastern U.S. and is very common in the South. The fungus,Fomes annosus, usually enters by infecting freshly cut stump surfaces. That makes annosus root rot a problem in thinned pine plantations. The fungus produces conks that form at the root collar on roots of living or dead trees and on stumps or on slash.

5. Aspen Canker

Aspen Canker
Quaking aspen (Populus tremuloides Michx.) is one of the most well-known and widespread tree species in the western United States. Several wound-invading fungi cause the majority of damage to aspen. The taxonomy of some of these organisms has changed in recent years and several scientific and common names are in use.

6. Bacterial Wetwood (slime flux)

Randy Cyr/GREENTREE Technologies/Bugwood.org
Slime flux is a major bole or trunk rot. The tree is trying its best to compartmentalize off the damage. "Weeping" sap from the rotting point is what you are seeing. This bleeding is a protective slow, natural draining effect on a destructive organism that needs a dark, damp environment with favorable culturing conditions at summer temperatures. One interesting thing is that the weeping liquid is fermented sap, is alchohol based and toxic to new wood.

7. Beech Bark Disease

Beech Bark Disease
Beech bark disease causes significant mortality and defect in American beech, Fagus grandifolia (Ehrh.). The disease results when bark, attacked and altered by the beech scale, Cryptococcus fagisuga Lind., is invaded and killed by fungi, primarily Nectria coccinea var. faginata.

8. Brown Spot in Longleaf Pine

Brown Spot in Longleaf Pine
Brown-spot needle blight, caused by Scirrhia acicola (Dearn.) Siggers, delays growth and causes mortality of longleaf pine (Pinus palustris Mill.). Brown spot reduces total annual growth of southern pines by more than 16 million cubic feet (0.453 million cubic meters) of timber. Damage is most severe on longleaf seedlings in the grass stage.

9. Canker Rot

Canker Rot
Canker-rot fungi cause serious degrade and cull in hardwoods, especially the red oaks. Heartwood decay is the most serious form of damage, but the fungi also kill the cambium and decay the sapwood for as much as 3 feet above and below the canker point into the tree. Canker-rots are most important on the red oaks, but also occur on hickory, honeylocust, some white oaks, and other hardwoods.

10. Commandra Blister Rust

Commandra Blister Rust
Comandra blister rust is a disease of hard pines that is caused by a fungus growing in the inner bark. The fungus (Cronartium comandrae Pk.) has a complex life cycle. It infects hard pines but needs an alternate host, an unrelated plant, to spread from one pine to another.
Related Video
What Is American Chestnut Blight?

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