Ailanthus trees are prized for their good health and lack of disease problems except for one issue: verticillium wilt. This wilt disease is caused by a fungus that attacks ailanthus trees among many other host plants. Become familiar with the signs to look for as well as effective means of management should fungus invade your home garden.
Ailanthus trees (Ailanthus altissima), also referred to as tree-of-heaven, are deciduous plants that have a greater ability to resist and ward off fungus infection problems when kept vigorous in comparison to stressed or weakened trees. Grow ailanthus trees in full sun for best growth. Ailanthus trees thrive in moist, well-drained soil but will grow successfully in almost any condition with tolerance to problems like smoke and hot temperatures, according to the University of Florida IFAS Extension.
Verticillium wilt is a fungal infection of ailanthus trees, caused by the fungi Verticillium albo-atrum and V. dahliae. These fungal pathogens are soil-borne where they invade through a tree's root system and move into the trunk, resulting in problems in all parts of the tree, according to the Virginia Cooperative Extension.
Look for leaves that wilt and display browning veins, stunted or decreased development of new branches and leaves, a crown with considerable leaf drop, branch dieback, and diminished health, according to the Virginia Cooperative Extension. Verticillium wilt in ailanthus trees inhibits the normal water and nutrient absorption from the roots upward throughout the rest of the tree, with the potential for severe decline.
Certain trees are susceptible to verticillium wilt while others are resistant or immune. When planting other trees or when re-planting a tree where an infected ailanthus was removed, avoid susceptible varieties that are more likely to suffer from disease. These vulnerable trees include, but are not limited to, maple, redbud, quince, ash, sassafras and slippery elm. Tree options with resistance or immunity are fir, hackberry, dogwood, fig, beech, sycamore, white oak and willow, according to the Virginia Cooperative Extension.
There are no effective chemical control methods for verticillium wilt on ailanthus trees, according to the Michigan State University Extension. The most effective control management is the control of microscopic organisms called nematodes that intensify fungal infections of verticillium wilt. Since application of the appropriate soil chemicals is not an option for the home garden, contact a licensed professional or your local county extension agent for chemical advice. However, for home landscape control, apply ammonium sulfate fertilizer to trees that display symptoms but not those with extreme infections, according to the Virginia Cooperative Extension. Remove and destroy affected plant parts and, in the case of a severe problem, remove the entire tree. Always sanitize tools like pruning shears between each cut and from use on an ailanthus tree to the next plant.