National Arborists
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VERTICILLIUM WILT

Verticillium Wilt is a soil-inhabiting fungus that attacks tree roots. After the tree is infected Verticillium Wilt attacks the conductive tissue of a tree. The tree counters the fungal invasion by blocking off the movement of water in the infected part of the tree - essentially cutting off the water supply to its own leaves.

TREES INFECTED BY VERTICILLIUM WILT

Maple trees are the most commonly seen landscape plant infected with Verticillium Wilt, however, the disease is known to attack over 300 various plant species. Other common host plants include:

Ash trees Azalea shrubs Barberry shrubs Boxwood shrubs Cherry trees Elm trees Golden Rain Tree Horsechestnut Japanese Pagoda Tree Kentucky Coffeetree Lilac shrubs Magnolia trees Peach trees Plum trees Privet shrubs Redbud trees Serviceberry shrubs Smoketree Spirea shrubs Tulip-tree Viburnum shrubs

HOW TO CONTROL VERTICILLIUM WILT

Corrective actions will improve the health of the tree and will reduce the pathogen population within the tree, but will not eliminate it.

Branches killed by Verticillium Wilt should be pruned from the tree. Pruning tools should be sterilized between pruning cuts. Tree fertilizing is recommended to increase the overall vigor of the infected tree or shrub. Supplemental irrigation should be applied to the infected tree or shrub during dry weather.

Avoid planting susceptible trees or shrubs in areas where Verticillium Wilt has been identified as a possible cause of plant decline or death. Landscape plants resistant to Verticillium Wilt include:

Beech trees Birch trees Crabapple trees Dogwood trees Evergreen trees Hackberry trees Hawthorn trees Hickory trees Holly shrubs Honey Locust trees Hornbeam trees Linden trees Mountain-ash trees Oak trees Pear trees Rhododendron shrubs Sweetgum trees Sycamore trees Zelcova trees

SYMPTOMS OF VERTICILLIUM WILT

Symptoms of Verticillium Wilt infection can vary depending on the host plant, but often include:

Yellow foliage Stunted growth Premature defoliation Sudden wilting & browning of leaves

In some instances olive-green streaking can be found in the sapwood of infected plants. A cross section of an infected branch may reveal a green to black ring in the sapwood of the branch.

The development of Verticillium Wilt within the tree may cease with the onset of warmer weather. Also, after the initial infection no further symptoms may develop for several years.

Sapwood streaking caused by Verticillium Wilt on a Maple tree.

Photo: William Jacobi, Colorado State University, Bugwood.org

Verticillium Wilt on a Silver Maple.
Photo: William Jacobi, Colorado State University, Bugwood.org

Verticillium Wilt causing wilted Maple leaves.
Photo: Joseph O'Brien, USFS, Bugwood.org

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