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Now Through October 31: the Critical Time to Prevent Oak Wilt Disease

Posted on: July 26, 2019 - 3:48pm
Trees

Knock on wood, Ferguson Township has no incidence of oak wilt disease to date this year. Preventive efforts seem to be working. With prevention in mind, Township Arborist Lance King reminds residents not to prune oak trees during this growing season through October 31.

How the Township is reducing the risk

It is illegal to trim oak trees in Ferguson Township between April 1 and October 31 without a free permit.  The Township put this limitation into place to reduce the risk and spread of oak wilt disease, which could decimate oak trees in your neighborhood unless it is controlled.  Oak trees pruned between April 1 and October 31 are more likely to become infected with oak wilt and die.  Infected trees can then spread the disease to other trees around them.  Two incidents of oak wilt-infected trees occurred in 2016 on Cherry Ridge Road in Park Forest Village.  The infected trees were removed and oak trees within a 200-foot radius of the dead trees were treated with fungicide.

Causes, symptoms and prevention of oak wilt disease

Oak wilt is a fungal disease transmitted by sap and bark-feeding beetles.  These beetles are especially attracted to trees with open cuts, or wounds, from which sap bleeds.  Fungal spores on or in the beetles are deposited in the sap while the beetles feed.  The fungus grows out of the sap and into the tree, where it quickly spreads throughout the tree and into the roots.  Symptoms of fungal infection generally consist of leaf discoloration (browning), leaf wilt, and the brown leaves falling off altogether.  Infected trees can then spread the oak wilt fungus to neighboring trees through connections between tree roots.  Prevention is essential because there is no permanent cure; once infected, a tree will die.

Preventing oak wilt disease

Fortunately, there are very effective ways to minimize the chances of your oak trees getting oak wilt:

  • Never prune oak trees from April 1 through October 31 — when beetles are active.  
  • Never allow individuals who work on your trees to climb them using boots with spikes or spurs that inflict sap-bleeding wounds in the tree. 

Ferguson Township Ordinances and Resolutions addressing oak wilt disease Ordinance 1023 stipulates fines for anyone (resident, contractor, etc.) pruning oak trees without a permit during April 1 through October 31 or climbing oak trees with boot spurs or spikes at any time of the year except for the purpose of removing the entire tree.

Sometimes there is no way to prevent oak trees from being wounded, particularly when storms break off live branches.  These naturally occurring wounds could attract sap beetles and result in an oak wilt fungal infection.  Therefore, Resolution 2016-32 includes helping private property owners shoulder the cost of abating an oak wilt infection on their property.  Abatement includes removal of the infected tree, proper disposal (chipped then burned or composted) of the wood, treatment of all oak trees within a 100- to 150-foot radius of the infected tree, and possibly trenching around the infected tree to break root grafts through which the fungus can spread.  Wood from an infected tree should never be moved to unaffected areas, even for firewood, so as to prevent beetles in the wood from dispersing the fungus into a new patch of trees.

Residents with oak trees on their properties are advised to be aware of the signs of oak wilt described above, especially leaves at the top of a tree turning brown and falling off altogether. 

Please report any tree-related concerns to any member of the Tree Commission. You’ll find their contact information here. You can also contact Lance King, Township Arborist at (814) 238-4651.

Thank you for cooperating to help maintain the health of our urban forest.