NORTH IOWA OUTDOORS: Cool Fall Weather Means its Time to Start Pruning Oaks

As the cool fall weather is upon us, it’s time to start pruning oak trees with minimal to no risk of spreading oak wilt.  The best way to prevent the spread of oak wilt is to prune during the trees dormant season. 

“There have been several days in a row that were at or near freezing and the risk of oak wilt is very minimal,” says Tivon Feeley, DNR Forest Health Program Leader.  For that reason, the DNR suggest that you start pruning your oak tree now until late winter.

Oak wilt is caused by a fungus and has been present in Iowa for many years. The disease is most commonly found in red, black and pin oak trees, but it can also be found in white and bur oak.  On most occasions, if red, black, or pin oak are affected by the fungus they usually parish within the same summer they become infected.  But, white and bur oak can often take several years before they parish.

A healthy tree can be infected by the fungus two different ways: 1). The fungus can be carried by a small beetle to an open wound of healthy tree and cause the disease. 2). A healthy oak can get the fungus through root grafts if it is located near an infected tree.

A common symptom of oak wilt includes leaves turning a bronzed brown along the outer margins of the leaves. The best way to avoid the spread of oak wilt is to prevent any wounding to oak trees during the growing season. If a tree is wounded from storm damage or pruning is required during the growing season, treat the wounds immediately with a wound dressing such as acrylic paint.  The DNR Forestry experts recommend avoiding pruning paints or sealants as they tend to slow the tree’s ability to heal the wound.

For more information on oak wilt prevention and control follow the link below: http://na.fs.fed.us/pubs/howtos/ht_oakwilt/identify_prevent_and_control_oak_wilt_print.pdf