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Storm Damage to Forests

Pests

Review the information below and contact your local DNR forester to discuss your management options in more detail.

Pines, stain and bark beetles

Following a severe storm event, pine trees degrade faster than hardwoods and are also likely to attract secondary pests such as bark beetles. Storm-damaged pines should be salvaged as soon as possible after the initial damage. Pine bark beetles attack and kill damaged pine and then spread to neighboring healthy trees. They can also introduce blue stain fungi, which rapidly discolors the wood and reduces timber value. To minimize future issues with bark beetles and blue stain, salvage pines as soon as possible. For more on bark beetles that attack conifers, including pines, read the conifer bark beetle factsheet [PDF].

Review this factsheet [PDF] for more information about salvage harvests, pests and replanting in storm-damaged pine stands.

Heterobasidion root disease

Heterobasidion root disease (HRD, previously known as annosum) is a serious fungal disease of conifers, particularly pine and spruce, that causes decline and eventual mortality. Infection occurs when a spore lands on a freshly cut stump and germinates on the surface. Once in a stand, HRD can spread from an infected stump to nearby living trees through root contact, eventually killing them. It also attacks and kills understory saplings and seedlings within a disease pocket.

If your pine or spruce stand is within 25 miles of a known HRD pocket and a harvest or salvage will be done, it is recommended to treat pine and spruce stumps with a preventative fungicide within 24 hours of being cut. Find out if you're within 25 miles of known pockets by exploring the DNR's interactive HRD web map.

Hardwoods, stain and decay

Open wounds on storm-damaged hardwoods allow for the entry of bacteria and fungi that stain and decay the wood. The rate of decay varies by both tree and fungal species. In general, aspen, birch, basswood and red maple decay more quickly than oak, hickory and sugar maple. Larger wounds covering more than one-third of the circumference of the tree can increase the likelihood of tree failure during future wind events. Prioritize removal of species that decay more rapidly and those trees that have large wounds.

Oak wilt

When salvaging hardwoods, keep in mind that oaks are highly susceptible to infection by the oak wilt fungus during spring and early summer with the highest risk between April 1 and July 15 in southern Wisconsin and April 15 and July 15 in northern Wisconsin.

If salvage of oaks will occur during the high-risk period, please see the oak wilt guidelines for more information on harvesting to minimize introduction of oak wilt.

Oaks that require pruning of broken branches should have the wounds painted immediately if pruning occurs from April to July. Wound dressing or latex paint is an acceptable sealant for pruning wounds.

Two-lined chestnut borer

Oaks with broken roots or major branch/stem breakage may be attacked by the native two-lined chestnut borer. Larvae of this beetle bore under the bark of oaks and can girdle and kill branches or entire trees. Branch mortality or whole tree mortality due to this insect will not show up for one to three years following a major stress event like these storms.

What to salvage

A general rule is to salvage the tree if more than 50% of the crown or top is broken, although there may be exceptions where leaving the tree can be beneficial. Trees that are partially uprooted or leaning will not die immediately but likely have severe root damage and will become hazardous if left to stand. They are also more susceptible to insect or disease attack. Consider these trees for removal unless a forester recommends that you leave them to promote future stand regeneration.

Firewood

Storm-damaged trees can be used for firewood, but you should be careful not to move firewood long distances and risk introducing invasive species like emerald ash borer, gypsy moth and oak wilt to new areas. Instead, let the firewood age in place and burn it locally. For more information, visit the DNR firewood page. Always use proper protective equipment when operating a chainsaw.

Continued monitoring

You should continue to monitor your storm-damaged stands for several years following the damage. This is especially important if additional stresses (drought, defoliation, etc.) occur in the year or years after the storm damage. If you notice trees dying within one to two years after the storm, you should discuss this with your local DNR forester.