Tree Health in Tennessee

A tiny aphid-like insect native to Asia that feeds on hemlock sap at the base of needles. It has devastated eastern hemlock populations from Georgia to Maine. Trees typically die within 4-10 years of infestation.

Southern Pine Beetle

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.

Japanese Beetle

An invasive beetle introduced to New Jersey in 1916. Adults skeletonize leaves of over 300 plant species while larvae (grubs) damage turf grass roots. They are particularly damaging to linden, birch, and fruit trees.

Bagworm

A moth whose larvae construct distinctive spindle-shaped bags from silk and foliage fragments. They feed on over 100 species of trees and shrubs, with conifers being most vulnerable since they cannot regrow lost foliage as readily.

Dutch Elm Disease

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.

Oak Wilt

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.

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.

Cedar-Apple Rust

A fungal disease requiring two hosts to complete its life cycle: eastern red cedar (juniper) and apple or crabapple trees. It causes economic losses in apple orchards and aesthetic damage to landscape cedars.

Anthracnose

A group of fungal diseases causing leaf spots, cankers, and shoot blight on many shade trees. Sycamore, dogwood, maple, and oak are commonly affected. Cool, wet spring weather promotes infection of newly expanding leaves.

Powdery Mildew

A widespread group of fungal diseases that produce a distinctive white powdery coating on leaves and shoots. It affects hundreds of tree, shrub, and plant species. Unlike most fungi, it thrives in warm, dry conditions with high humidity.

Apple Scab

The most economically important disease of apples worldwide. The fungus overwinters in fallen leaf litter and releases spores during spring rains. Severe infections reduce fruit quality and yield and can defoliate trees by mid-summer.

Chestnut Blight

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.

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.

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.

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.

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.

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.

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.

Phytophthora Root Rot