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.
Controlling Existing Infection Centers
Disrupting the connections between the roots of infected and healthy trees limits the spread of oak wilt and is an effective control measure. Infected trees and their roots will usually die before root grafts can be re-established.
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.
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.
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.
Many years of field application have proven that Alamo® when applied via Macro Flare Root Injection is very effective against Oak Wilt. In fact, if the procedure is performed correctly on appropriate candidates and repeated as necessary, survival rates are 85% or better.
Propiconazole is the only fungicide scientifically tested and proven effective (when properly applied prior to infection) for use as a preventative treatment to protect live oaks.
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.
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.
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.
Vertical cracks, seams, dead branch stubs and large, older wounds suggest internal decay. Severe damage to the main trunk often warrants removal of the tree. If the damaged area is less than 25 percent of the circumference of the trunk, the wound could gradually heal over and no permanent injury should result.
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.
Cutting down a tree with oak wilt that is still partially alive can cause the disease to spread, but removing it during the least vulnerable months can prevent this.
Oak Wilt Spread
The Oak Wilt fungus is spread via two ways: above ground and below ground. The above ground movement is facilitated by a sap-feeding beetle that carries the fungal spores to new trees. The below ground movement occurs when the fungus travels from tree to tree through interconnected roots.
Healthy oak trees are not susceptible to oak wilt in an infected area. Bur oak, white oak and other members of the white oak family are resistant to the fungus and can be planted in oak wilt centers. For additional prevention measures, plant tree species other than Oaks to guarantee no infection from the disease.
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.
Because these injections introduce the desired product directly into the xylem of the tree, this allows for faster uptake than a soil drench. It also eliminates the risk of spray drift and dilution from the weather. Depending on the chemicals being used, these injections can last anywhere from one to three years.
The systemic fungicide Alamo has been used as a preventative treatment in highly valued red and white oaks, and as a curative treatment in white oaks.
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.
Spread through Roots
Infection centers among live oaks in Texas expand at an average rate of 75 ft per year, varying from no spread to 150 ft in any one direction.
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.
Fungicide treatments are a popular and effective method for treating oak wilt in its early stages. This involves injecting the fungicide directly into the tree to prevent the fungus from spreading. However, this treatment may not be effective in advanced cases of oak wilt.
There is no effective fungicide or other cure for Fusarium wilt. The pathogen nearly always kills infected hosts. Prevention and exclusion are the only effective management strategies.
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.