ROLE OF ARBORISTS IN IDENTIFYING AND TREATING OAK WILT

Arborists, landscapers and other providers of tree care services can reduce the probability of spreading oak wilt during pruning and tree removal operations by understanding how oak wilt is spread, and taking the following precautions: 

  1. Avoid pruning oak trees during the greatest or lower risk periods.
  2. Immediately paint any pruning cuts made during greatest risk period. 
  3. Treat cut stumps as a new wound and seal immediately with sealing paint (shellac or any latex paint).
  4. Never use climbing spurs on any tree unless doing tree removal or absolutely needed for hazard abatement.
  5. Advise clients of the need to isolate the infected tree by severing its roots from adjacent oaks before removing the infected tree. Severing is accomplished by installing 5ft deep vertical trench lines.
  6. Additional management practices may include fungicide injections (propiconazole) to non-symptomatic oak trees. The fungicide can protect oak trees from infection for a period of time. Repeat injection treatments are required for the duration of time the pathogen is viable in the root system (known up to five years*).
  7. The infected tree can produce oak wilt spores up to one year. Therefore remove oak wilt infected trees  and chip, burn, debark or bury the wood prior to April 1 the year after it dies. If splitting into firewood stack, cover and seal to the ground with 4-mil plastic sheeting for one year to prevent insect access and until wood dries.
  8. Provide training about oak wilt to all personnel who work on trees or discuss tree work with clients.
  9. Provide clients with accurate information including handouts and websites with more information. See Resources/Research page.

Arborist Resources:

*Amos, R.E.; True, R.P. 1967. Longevity of Cetatocystis fagacearum in roots of deep-girdled oak-wilt trees in West Virginia. Phytopathology. 57(10): 1012-1015.

 

FORESTERS

ROLE OF FORESTERS IN IDENTIFYING AND TREATING OAK WILT

In the natural resource professional field, no other group has the opportunity to cover more ground or see more trees with educated eyes than foresters. Field foresters can walk through hundreds of acres every week. Back before there were forestry schools in the U.S., they were called “landlookers”. The same term still applies today. All foresters should take every opportunity to inform and educate clients and constituents about the April 15th – July 15th high risk time for infection.

  • Consultant foresters work for private landowners, and are looking out for their interests. They do inventories/timber cruising, write management plans, handle timber sales, and wildlife habitat projects.
  • Industry foresters represent wood using companies They are managing company lands and also work with private landowners to help manage their timber resources.

These foresters should seek training, and familiarize themselves with the symptoms, identification, and treatment of oak wilt, to pass the info along to their clients.  Be on the lookout for expanding pockets of dead oak, and ‘killing fronts’ advancing through the woods. Hot spots are frequently around camps, cabins, and lakeshore lots, caused by relocating oak wilt infected firewood or ill- timed pruning or logging in years past. Look for oak trees suddenly losing their leaves in the height of summer leaf-out, into September.

  • There are 20 Conservation District (C.D.) foresters serving 51 timbered counties in Michigan. As a free public service, they are assigned to work with private forest landowners on, among other things, forest health issues. The C.D. foresters receive classroom and field training to identify, and recommend treatment options for oak wilt. They can also submit tissue samples from suspect trees to M.S.U. Diagnostic Services for confirmation of the fungus in that tree. The cost of the lab sample is reimbursed by a grant.

A professional forester will help you identify and determine a plan of action for an oak wilt infestation. If oak wilt is found in a forest setting, it is most important to isolate all the trees that are infected. It is also important to speak with your neighbors, as their oak trees may also be infested.  In general, you and your forester should follow these management guidelines:

If oak wilt is found in a forest setting, it is most important to isolate the tree that is infected. To do this, follow these guidelines:

  1. Avoid harvesting oaks during the greatest risk period according to the "oak wilt risk meter" and MDNR guidelines.
  2. Immediately paint any injuries/pruning cuts made during your operations and the greatest risk period.
  3. Treat cut stumps as a new wound and seal immediately with sealing paint (shellac or any latex paint).
  4. Isolate infected tree(s) by severing their roots from adjacent oaks before removing the infected tree(s). Severing is accomplished by installing 5ft deep vertical trench lines.
  5. The infected tree can produce oak wilt spores up to one year. Therefore remove oak wilt infected trees  and chip, burn, debark or bury the wood prior to April 1 the year after it dies. If splitting into firewood stack, cover and seal to the ground with 4-mil plastic sheeting for one year to prevent insect access and until wood dries.
  6. Provide training about oak wilt to all personnel who work on trees or discuss tree work with clients.
  7. Provide clients with accurate information including handouts and websites with more information. See Resources/Research page.
  8. For further information, consult with a certified arborist/forester with oak wilt management experience, or contact the Oak Wilt Coalition.

Forester Resources:


Oak Wilt Lab Submittal Form

ASM will pay for your oak wilt sample to be verified through the MSU Diagnostic Laboritories in Lansing, MI from a grant through the Michigan Invasive Species Grant Program. Only samples submitted by arborists and tree care companies are eligible for reimbursement through ASM. Click here to download the form.


ROLE OF TIMBER HARVESTERS

By far, the easiest way to stop oak wilt is to prevent infection. The highest risk season for overland infection is between April 15th and July 15th. Consider completing harvesting in oak forests by April 15th. Consider delaying harvests in oak forests till after July 15th.

Remember just because your thinning red pine or harvesting aspen during these high risk months, be aware that pruning limbs on access roads and improving roads for heavy hauling will probably injure oak trees. Oak trees that have had bark knocked off are at risk for infection just as if it had been cut with a saw. Consider carrying a spray can of tree wound paint or latex paint to immediately paint any wound on oak trees.