Oak Wilt is a deadly fungal disease that has put all oak trees in northeast Ohio at risk. Once infected, there’s no known cure for Oak Wilt – so prevention is the best option for saving your oak trees.
4 Steps To Prevent Oak Wilt Infection
1. Avoid Pruning or Damaging Oak Trees Between April 15 and October 1
Oak Wilt is spread in part by a variety of different beetles that are attracted to fresh pruning wounds on oak trees.
Once the weather warms up in spring (after a few 50-degree or warmer days), the beetles become active and start looking for food. As they move around, they brush up against parts of dead or diseased oak trees that harbor the Oak Wilt fungus and end up getting covered in fungal spores. As they later move to healthy oaks, the beetles carry those spores with them and infect new trees through the fresh pruning wounds.
So, other than the arrival of another Ice Age, the best preventive measure is to not attract these fungus-carrying beetles to your healthy oak trees.
Since beetles are most active between April 15 and early to mid-July, avoid pruning oak trees during that time. However, it’s possible that some beetles will remain active throughout the growing season so, if you can, it’s best to wait with oak tree pruning until early October.
The Oak Wilt fungus can also enter trees through other types of harm to the tree bark, including holes from tree-climbing spikes (never allow the use of spikes on a live tree unless it’s being removed!), rights-of-way pruning, nailing signs on trees and accidental damage to tree bark (for example, wounds caused by impact from equipment, falling trees and other objects). If that happens during the growing season, immediately cover the wound with latex or tree wound paint (see tip 3 below).
2. Disinfect Pruning Tools
Whenever you do any pruning or trimming work on an oak tree, always disinfect your cutting tools before and after work. This includes pruning shears, loppers, pruning saws and chainsaws. And ensure that anyone working on your oak trees also follows this important prevention step.
Any all-purpose household disinfectant will work, including bleach (mix it with water first). You can also use denatured methyl/isopropyl alcohol.
3. Paint Tree Wounds Immediately
Whenever and however the bark on an oak tree is damaged, immediately paint over the wound with latex or commercial tree paint. Use just enough to cover the wound – no need to completely seal it. While this may slow down healing of the wound (and isn’t recommended for other trees), it prevents beetles from “smelling” the fresh oak sap and getting into the living tissue inside the tree where the fungus can spread.
Use a cheap latex paint (no need to go for the “good stuff”) that doesn’t have a rust inhibitor. And don’t use oil-based paint as it can damage the living tree tissue.
4. Dispose of Diseased Oak Wood Properly
Many people like to use oak as firewood. But if that firewood comes from an Oak Wilt-infected tree, be careful.
If the bark has fallen off the wood, it’s probably safe.
But if there’s any bark still attached, carefully stack your firewood in a sunny area, cover it with a thick tarp or plastic sheet all the way to the ground. Weight the edges of the tarp and fix any holes so the pile of firewood is completely sealed. This prevents beetles from getting into or out of the oak firewood and builds up heat inside the pile that will kill the Oak Wilt fungus.
Leave the tarp in place for at least a year and don’t remove it until October after the danger of spreading the fungus has passed.
Finally, don’t move firewood from a diseased oak to another location – you’ll just be spreading the fungus and probably infecting healthy oak trees.
What To Do If Your Oak Tree Is Already Infected
If your oak tree is already infected with Oak Wilt, or if you suspect it may have Oak Wilt, give us a call at 440-564-1374 or contact us online. As ISA Certified Arborists we’re experienced in diagnosing and evaluating infected trees. We can tell you which of your oaks are infected and whether or not it’s possible to treat any healthy oaks on your property. We’ll also give you an estimate for the safe removal of any Oak Wilt infected trees
Removal is the only option once an oak tree is infected with Oak Wilt, which is why prevention is so critical.
If you’d like more information about Oak Wilt in northeast Ohio, please see our Oak Wilt Resources page.