|Table: Diagnosis and Control of Verticillium Wilt|
|Pest Identification||Host Plants||Damage Symptoms|
|Verticillium Wilt of Maple
|Maples (sugar, red, and Norway) as well as elm, ash, and catalpa. Verticillium also occurs on many hosts other than trees.||Symptoms caused by verticillium wilt include drought wilt-like symptoms, which appear as yellowing or browning leaves. These symptoms usually are the most prevalent during dry periods or on a dry site. Verticillium wilt usually causes wilting of one or more branches and not the whole tree. However, in small trees the entire crown may wilt. Verticillium may be an acute disease in which the tree is killed quickly or a chronic disease in which the tree shows symptoms and remains infected for a period of years. Infected trees usually do not recover. Many infected trees will also have a staining in the sapwood that appears green in color.|
|Beginning in early summer and continuing through early fall, maple trees should be monitored for wilt like symptoms. Trees that appear to be wilting should be examined for green staining of the sapwood.||There are no chemical controls for verticillium wilt. Verticillium wilt can be managed by pruning infected branches, and improving the vigor of the tree through watering and fertilizing. Since verticillium may persist in trees for a period of years, it is not necessary to immediately remove the tree. If the tree dies do not plant a susceptible variety or another susceptible host in the same area.||None|
|Description and Life History|
Description: Verticillium wilt is a fungal wilt disease that infects the vascular tissue
of maples. This disease produces spores in the xylem tissue, as well as specialized structures
for long term survival. These structures are known as microsclerotia and can persist in the soil
for 2 or more years. |
Life history: Microsclerotia persisting in the soil produce spores that enter the host through wounds, usually root wounds. Once the fungus has infected the host, it begins to grow in the xylem tissue and to produce spores. This causes a blockage of the vascular tissue and in turn wilting of the tree. The fungus then produces microsclerotia for long term survival.
Overwintering: The fungus overwinters in the infected tree or in the soil as microsclerotia.
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