Timing of Oak Pruning for Oak Wilt

Date April 26, 2023

Author TreeNewal Staff

Once spring arrives, many homeowners head outside to enjoy some fresh air and tackle a variety of tasks around the yard. They might gather weed trimmers, mowers, and pruners to make their yard pristine and ready for the warmer weather. While spring is an excellent time to undergo yard maintenance, homeowners should keep oak trees off the list of plants to prune because of the risk of oak wilt.

What Is Oak Wilt?

Image via Pixabay by MabelAmber

Caused by a fungus, oak wilt is a lethal disease that affects oak trees. It often spreads through disease spores found on the bodies of sap beetles. These insects have an incredible sense of smell and use it to seek out pruned or wounded surfaces on oak trees. They feast on the sugary sap and can spread the disease in as little as 15 minutes as they feed from tree to tree. Wounds aren’t susceptible to oak wilt after 72 hours of exposure.

Oak trees found in the red oak group, such as Shumard,Texas red oak, and Southern red oak, are often affected by oak wilt. Live oaks are also commmonly affected. The U.S. Department of Agriculture states that infected red oaks might die over several weeks or months, while live oaks can sometimes last several years. Trees in the white oak group, such as bur, post, and white aren’t as susceptible.

When Should Homeowners Prune Oak Trees?

Timing of oak pruning for oak wilt prevention is imperative. To reduce the risks of spreading this disease, homeowners should avoid pruning oak trees from February through June in areas of oak wilt transmission. The high risk of infection decreases dramatically after June, so homeowners should refrain from pruning their oak trees before the leaf buds develop. Ideally, pruning should occur during the dormant season. According to Don Kissinger, who is a DNR Urban Forester in Wisconsin, deciduous trees that lose their leaves in the fall have low food reserves in the spring, so the best time to prune is in the winter.

However, if homeowners need to prune oak trees immediately due to weather damage, they should treat the trees with either a latex-based paint or tree wound dressing to seal the wound. Fresh wounds need attention because they attract the insects that carry diseased spores.

What Can Homeowners Do to Prevent Oak Wilt?

Pruning during the best times of the year can lower the risk of oak wilt, but homeowners can take additional steps. They can contact a technician who specializes in oak wilt to apply Propiconazole, which is the only fungicide scientifically tested and proven to protect live oaks against wilt. The technician drills small holes into the tree’s root flares at the base and injects the fungicide into the tree’s vascular system. It’s important to note the fungicide doesn’t stop root transmission of the fungus.
Despite taking precautions against oak wilt, some oak trees can still become infected. Dallas-area homeowners in need of assistance with oak wilt can reach out to TreeNewal. Our team of ISA-certified arborists has 15 years of preventing oak wilt and can help property owners deal with the issue.