Is an Ailanthus Tree Dying if It's Losing Its Leaves?

Symptoms

• Tree of heaven is susceptible to verticillium wilt, a soil-borne fungus that causes symptoms such as wilted foliage, leaf scorch, premature defoliation and branch dieback, often located primarily in one part of the tree. Leaves can curl or turn red or yellow in the areas between the leaf veins. When cut into, broken branches may show streaks of discoloration. Sometimes verticillium wilt spreads rapidly and kills the tree in one or two years, but it can also move through periods of remission and be worse some years than other.

Control

• To help limit the infection and improve the tree's overall vigor, the Ohio State University Extension recommends pruning out infected, dying branches and disposing of them. This will not eliminate the disease though, because the fungus travels through the roots. Do not recycle dead branches into mulch unless you can heat treat them to kill the fungus. Sterilize your pruning equipment before and after use to avoid spreading the disease to healthy trees. Fungicide is not effective against wilt. Keep the tree healthy by following good cultural practices.

Culture

• Tree of heaven is best suited for a bright, sunny location in U.S. Department of Agriculture plant hardiness zones 5a to 8a. Though it tolerates adverse growing conditions such as pollution and poor soil, the tree prefers a well draining, moist soil. Water it regularly during periods of drought to maintain its vigor. This is especially important for trees infected by wilt. You'll need to regularly prune off suckers to keep the tree looking tidy and to prevent new trees from forming.

Considerations

• Tree of heaven is considered a non-native invasive tree because of its tendency to self-sow and grow just about anywhere. The University of Connecticut Extension describes the tree as a "noxious weed in many places," noting that it's generally short-lived and its weak wood breaks easily. Even if your tree is not infected by wilt, it may be better to remove the tree altogether to keep it from spreading throughout your garden and the surrounding habitat. To remove the tree permanently, you must cut it down and apply an herbicide such as triclopyr to the stump, following label recommendations. Keep all herbicides away from children and pets.