To slow above-ground movement of oak wilt, cut down diseased oaks in late autumn or winter after all trees have dropped their leaves for the fall.
What to do if your tree has oak wilt - If your oak tree has been diagnosed with oak wilt, have it removed ASAP to stop the disease from spreading. Once the tree has been cut down, have all of the roots around the tree severed so the disease cannot pass to neighboring trees.
Contrary to what many homeowners assume, summer is the worst time of year to cut off oak branches. Instead, it's best to prune from late fall to early spring—November 1 to March 31, to be precise. These are the months when oak trees are less vulnerable to disease and infestations.
Live oak trees infected with oak wilt usually die within two to four months. Adjacent trees begin to drop their leaves and die a few months later as the disease progresses from tree to tree through the interconnected root system.
While the best time for tree treatment may be in the spring after the new leaves have set, successful treatments can be made at any time that there are sufficient green leaves on the tree to be treated. We've found that if the Oak Wilt threat is imminent, a treatment should happen soon to avoid major damage.
Once an Oak has Oak Wilt there is no cure, no matter what anyone tells you. You may be able to slow the decline down for a bit by treating it with the fungicide Propiconazole but eventually the tree will succumb to the fungus. Propiconazole is a very strong fungicide and is used more as a preventative than a treatment.
A couple of key concepts are important to remember: First, there's oak wilt. To avoid the chances of being infected with this deadly disease, pruning should be avoided, if at all possible, from February through June, when the insects that vector this disease are most active.
Trees in the red oak group generally die rapidly, usually within weeks or months after infection. Treatment will not save an infected red oak. Trees in the White oak subgenus, such as Burr oak and Chinkapin oak, can generally be treated for oak wilt and will recover within a year of treatment.
Finally, I'd like to note that chainsaws do not transfer oak wilt and are self-sterilizing on account of the operating temperature exceeding the temperature that the fungus can live in.
Firewood from unknown origins should be burned during the winter months. If possible, do not store it to the next season. (Note: Burning firewood with oak wilt spores does not spread the fungus! Fungal spores burn, too.
But oak trees have unique pruning needs because they can be infected with oak wilt, a deadly disease brought on by pests that prey on fresh pruning cuts. Oak wilt is most active from April to July, which is why you should never trim oak trees in the summer.
How much can you trim off a tree without killing it? You don't want to remove more than 25% of the foliage from a tree in a single year. Removing too much foliage or too many branches at once could damage your tree beyond repair.
Generally, it costs between $350 and $1,385 to have an oak tree professionally trimmed. An oak tree needs trimming when its branches are too close to power lines or buildings.
To stop the spread of oak wilt through the root system, trenches can be placed around a group of trees, at least 100 feet away from the dripline of infected trees and at least four feet deep, or deeper, to sever all root connections.
How much does treatment cost? Fungicide treatments are based on the diameter of the tree and therefore vary quite a bit. The average tree costs about $250 to treat once. However, there are discounts available for larger projects.
Homeowners can reduce the risk of oak wilt infections by not pruning or otherwise injuring oaks after April 15. While high risk of infection decreases to lower risk after mid-July, it's prudent to simply avoid pruning oak trees from just prior to bud break to leaf drop. This means April to November.
Biology & Symptoms:
Trees in this group completely defoliate and die within three to six weeks after initial wilt symptoms occur. Some oaks, including live oaks, develop brown veins in their leaves, although green tissue remains. Early symptoms are wilting, bronzing, and shedding of leaves at the ends of branches.
Preventing New Infection Centers
Once an oak tree becomes infected with oak wilt, there is no known chemical treatment that is capable of “curing” the disease; however, fungicide research is continuing.
You can easily treat against infection and death of trees by oak wilt using DIY trunk injection of the fungicide Propiconazole 14.3 using reloadable Chemjet® Tree Injectors. The procedure is as follows for trees that have not yet been infected (indicated by leaves turning brown or falling off prematurely during summer.
Late Fall to Winter (November – March): This is the safest period for trimming oak trees. Avoid Spring and Summer: These seasons increase the risk of oak wilt, a deadly fungal disease that spreads through open wounds.
If there is concern that a red oak may have been infected with oak wilt, then its wood should be immediately burned, buried, or chipped. Fire will kill oak wilt, and there is no risk of spores being transported by smoke.
Remember: pruning trees in spring can leave them more vulnerable to insect infestation and diseases. That's why you don't want to prune these trees in spring, summer, or early fall: Oak trees to reduce the chance of oak wilt (if oak wilt is in your area) Elm trees to reduce the chance of Dutch elm disease.
A good indicator of oak wilt infection is a carpet of leaves under an oak in mid-summer. Red oaks infected with oak wilt lose about 90 percent or more of their leaves in 1–2 months; bur and white oaks quickly lose leaves from a few branches during the summer over several years.
Pruning mature oak trees at home is best kept to the smaller, lower branches that need pruning. Any branches up high in the tree should be left to a professional to cut.