Tennessee

A devastating vascular wilt disease spread by elm bark beetles that has killed millions of American elms since the 1930s. The fungus blocks water-conducting vessels, causing rapid wilting. It fundamentally changed the American urban landscape.

Affecting 45 regions

Oak Wilt

CRITICAL

A lethal fungal disease that affects all oak species, with red oaks dying within weeks of infection. It spreads through root grafts between neighboring oaks and via sap-feeding beetles. White oaks are more resistant but not immune.

Affecting 18 regions

Chestnut Blight

CRITICAL

A fungal disease that functionally eliminated the American chestnut as a canopy tree species in eastern forests by the mid-20th century. Once numbering in the billions, mature American chestnuts are now exceedingly rare. Root sprouts survive but are re-infected.

Affecting 25 regions

Southern Pine Beetle

Insect

The most destructive bark beetle in the southeastern United States, capable of killing vast stands of pine trees during outbreaks. Adults bore into bark and introduce blue stain fungus that clogs water-conducting tissues.

Affecting 13 regions

Fire Blight

A bacterial disease that primarily affects members of the rose family, including apple and pear trees. It can destroy entire orchards in a single season. Bacteria spread rapidly during warm, wet spring weather through blossoms and wounds.

Affecting 32 regions

Thousand Cankers Disease

A disease complex involving the walnut twig beetle and an associated fungus that has caused significant mortality of black walnut, particularly in western states. Thousands of small cankers coalesce to girdle branches and the trunk.

Affecting 15 regions

Armillaria Root Rot

One of the most widespread and destructive forest diseases in the world, caused by a complex of honey mushroom species. It attacks stressed trees through root contact and can persist in dead stumps for decades, infecting nearby healthy trees.

Affecting 36 regions

Fusiform Rust

The most damaging disease of loblolly and slash pines in the southeastern US. It causes spindle-shaped galls on stems and branches that weaken trees and make them susceptible to wind breakage. Oaks serve as the alternate host.

Affecting 11 regions

Laurel Wilt

A lethal vascular disease of trees in the laurel family, vectored by the non-native redbay ambrosia beetle. It has devastated redbay populations in the southeastern coastal plain and threatens sassafras, avocado, and other lauraceous species.

Affecting 11 regions

Bacterial Leaf Scorch

A chronic bacterial disease that affects many shade tree species, particularly oaks, elms, sycamores, and maples. The bacterium is transmitted by xylem-feeding leafhoppers and spittlebugs and colonizes the water-conducting vessels, restricting water flow. Symptoms worsen each year as more of the canopy is affected. There is no cure.

Affecting 19 regions

Verticillium Wilt

A soilborne fungal disease that affects hundreds of plant species including maples, elms, redbuds, and many other trees. The fungus invades through roots and colonizes the vascular system, blocking water transport. Symptoms often appear suddenly on individual branches. Maples are particularly susceptible. Olive-green to brown streaking in the sapwood is diagnostic.

Affecting 27 regions

Phytophthora Root Rot