There is no cure for oak wilt, so it's important to remove infected trees. However, there are disease management factors to consider before cutting them down. Trees are most susceptible to becoming infected with oak wilt between April and July.
As such, you should cut down oak wilt trees in either fall or winter, when your trees are dormant or entering dormancy, to minimize the risk of spreading the infection. If you cut down an infected tree that is partially alive in spring or summer, the disease can easily spread to other trees in your yard.
It may be burned up or taken to an approved yard waste facility.
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.
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.
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.
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.
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.
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.
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.
Once infected, the only traditional way to stop the spread of oak wilt from tree-to-tree underground is to disrupt underground root grafting using expensive, heavy equipment.
The most notable indicator of the presence of oak decline is deterioration of the canopy. Additionally, unlike oak wilt, trees affected by oak decline tend to retain their leaves, even after their death, and the leaves do not reflect the same patterns of necrosis that leaves of trees affected by oak wilt display.
Dying Oak Tree Solutions
Taking swift action to identify, treat, and get professional help for your tree significantly increases the chances of saving it. Ignoring the signs of a declining tree leaves it vulnerable to infestations, infections, and structural problems that will lead to its rapid decline and death.
Maintenance pruning your oak trees should be done between November 1 and March 31. This is the SAFE period to prune them. It is recommended to avoid pruning any oak trees throughout the growing season which is April 1 - November 1.
(Note: Burning firewood with oak wilt spores does not spread the fungus! Fungal spores burn, too. The risk comes from transporting infected firewood and storing it where the spores can be picked up by beetles and carried out to infect nearby healthy oaks.)
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.
Once an oak tree is infected with the oak wilt fungus, the tree will die and there is no treatment to save the tree. When an oak wilt infection is confirmed treatment can be applied to the surrounding trees to prevent the spread of this disease.
For this step to be successful, several “healthy” oaks surrounding the pocket of wilting or dead oaks usually need to be sacrificed because they likely already have oak wilt in their root systems. The treatment boundary installation usually occurs from August through early winter, depending on the method used.
Tree Injection With Systemic Fungicide: Trees within the buffer zone can be treated with a systemic fungicide (See Photo). Alamo is the product labeled for use in the control of oak wilt. It is applied by injecting the fungicide into the root flares. Alamo is most effective when applied as a preventive treatment.
Additionally, increases in air and soil pollution have made oak trees more vulnerable to disease, making them susceptible to the damaging effects of bacterial infections and fungal blight.
First, leaves turn dull green or bronze, can appear water-soaked, and wilt.
Oak wilt spreads naturally in two ways: above ground by sap beetles that deposit spores on fresh wounds, and below ground through roots of different trees that have grown together, called root grafts. Sap-feeding beetles typically fly less than 0.5 miles from an infected oak to a fresh wound.
Pruning between April 15 and July 15 should be strictly avoided because this is when beetle activity and viable spores are most prevalent across the landscape. If pruning an oak is absolutely necessary during this time, wounds should be immediately sealed with pruning sealer or water-based paint to prevent infection.
Disease Characteristics
Oak wilt is identifiable by the rapid pattern of wilting starting from the top of the tree and progressively dying down to the bottom, and on specific leaves, wilting from the edges to the base.