What are Dead Man’s Fingers?
What are Dead Man’s Fingers?
What are Dead Man’s Fingers? Dead man’s fingers is the name of a mushroom-like fungal growth that can be found at the base of dead or dying trees and shrubs, as well as wood objects (e.g., wood barrels) that are in contact with soil. Wood-decomposing fungi produce some types of dead man’s fingers. Others are produced by fungi that cause black root rot. This disease typically is a problem on stressed trees or shrubs, including apple, crabapple, pear, cherry, plum, American elm, Norway maple, and honeylocust.
The most recognizable form of dead man’s fingers is black and club-shaped with a white interior. It appears as solitary or clustered irregularly shaped “fingers” about 1½ to 4 inches tall, growing on or near dead or dying wood. In the spring, the early stage of the “fingers” is pale, often bluish with white tips. Disease-causing species of the fungus can form a sheath around roots that is at first pale. This sheath later becomes black and crusty, hiding a lighter interior. This sheath/crust can sometimes be seen if the soil is brushed away from tree/shrub roots. Trees/shrubs with above-ground symptoms of infection may show decline, dieback, slowed growth, and basal cankers. Infected apple trees may produce an abnormally large crop of smaller than normal-sized fruits.
In urban settings, dead man’s fingers may grow from wood mulch, and may not be an indication of disease. If the “fingers” are considered unsightly, they can be removed and discarded. If dead man’s fingers form around or near the base of an apple, crabapple, or other known susceptible host, the fungus may be infecting the tree causing black root rot. In such a situation, the infection is well advanced by the time the characteristic “fingers” appear. An infected tree should be carefully removed including the stump and as much of the root system as possible. DO NOT use wood from Xylaria-infected trees for mulch. There are no fungicides registered in Wisconsin for the treatment of black root rot.
DO NOT plant susceptible trees or shrubs in a site where dead man’s fingers have been observed. In addition, make sure that susceptible trees/shrubs in other locations are well watered, fertilized, mulched, and otherwise maintained to reduce stresses that might predispose them to infection by disease-causing species of Xylaria. Unfortunately, resistant varieties/cultivars of trees and shrubs known to be susceptible to Xylaria (see above) are not available.
If you have any concerns regarding your landscape, call Johnson Ops Tree Care at 608 526-6297
