What is Oak Wilt Fungus and How To Get Rid of It?

Get rid of oak wilt fungus

Throughout human history, the majestic oak tree has been a symbol of strength, stability, and endurance.

However, the durability of this mighty tree is being put to the test with the rise of the invasive fungal disease known as oak wilt.

These seemingly indestructible trees are dying off in droves all across the country due to this incredibly destructive tree disease.

In Texas alone, oak wilt has killed more than 1 million trees across dozens of counties. So what exactly is oak wilt and, more importantly, how can we protect our majestic oaks from falling victim?

Understanding how this infectious disease operates is essential in how we can help to prevent more unnecessary tree death. Follow along to learn how you can help defend oak trees in your hometown.

What is Oak Wilt?

Oak wilt is a part of the common invasive tree diseases originally from Latin America that is caused by the Bretziella fagacearum fungus.

This particular disease attacks the vascular system of trees disabling their ability to move water and nutrients throughout the tree.

Disrupting the water conduction system in a tree causes leaf discoloration, wilting, loss of leaves, and eventually tree death.

Oak trees are classified into two different groups, red and white oaks. The latter of these two groups is much more resistant than its unfortunate relatives.

In fact, white oaks rarely die from oak wilt. Red oaks, however, are very susceptible to oak wilt and typically die within a few short weeks of infection.

How is Oak Wilt Spread?

Understanding how oak wilt spreads is key to preventing and treating it. There are three pathways this fungal disease utilizes to infect oak trees.

The first is by taking advantage of the complex and intermingled root systems of the trees to spread.

Oak wilt pathogens are able to travel through the roots of an infected tree directly into the roots of unaffected trees.

Oak wilt can also spread to new trees through the movement of infected wood. This fungal disease can stay active of wood cut from infected trees and spread to new areas when moved around for removal or use of firewood.

This disease is also commonly spread by beetles. During the springtime, the oak wilt fungus causes fungal mats to form on the trunks and branches of red oaks.

These fungal mats begin under the bark of infected trees and grow outward causing cracks of open fungal infection on trees.

Nitidulid (or sap) beetles are attracted to the smell emitted by these fungal mats and subsequently, feed off them.

Diseased fungal spores then become attached to these beetles and can cause oak wilt in new trees when these beetles land on open cracks and wounds.

Unfortunately, these beetles have successfully managed to spread oak wilt over long distances causing mass tree deaths.

How Do You Know if Your Trees Have Oak Wilt?

Typically, the first visible sign of oak wilt disease in trees is leaf discoloration beginning around the top of the tree.

This change in color is know as veinal necrosis and causes leaf veins to turn yellow and eventually brown. As the disease progresses, the discoloration will be visible on whole branches throughout the tree. 

Another symptom to watch for along with leaf color changes is open cracks or wounds on the bark of the tree.

These could be fungal mats caused by oak wilt. Over a few short weeks, leaves will then begin to wilt and fall leaving the tree mostly bare. Brown veins should be obvious on the fallen leaves.

After leaf loss and wilting, tree death is usually swift in arrival for red oaks. Infected white oaks may display some of these symptoms, but at a slower rate and usually doesn’t end in tree death.

Oak Wilt Prevention

Prevention is absolutely essential in the management of this highly destructive tree disease.

In order to help protect the majestic oaks on our properties and in our communities, it is vital to understand how to spot and handle oak trees infected with oak wilt disease.

This fungal disease spreads primarily through open wounds, so pruning of oaks should be avoided between February and July.

During this time, sap beetles are active and fungal mats are also more likely to form on trees. It’s best to prune oaks during the high heat of summer or the deepest cold of winter.

Both are times when sap beetles are less likely to feed on infected trees.

Sanitizing your pruning tools should always be an included step in your landscaping process. Fungal spores can travel to infect new trees via your pruning tools.

However, applying isopropyl alcohol or even a general-purpose household disinfectant between trees can make all the difference in stopping the spread of oak wilt.

You should also cover open wounds on all your oak trees (whether the cracks are from pruning or form naturally) with a tree wound dressing or latex paint.

This can prevent disease-infected beetles from contaminating your trees.

Finally, all oaks that have died or are dying from oak wilt must be carefully removed. It is important to remember that infected wood can cause disease in nearby trees and new areas when moved.

Burn the infected wood nearby but keep all wood from interacting with other trees if possible. Never move infected wood to new areas for use as firewood.

How to Treat Oak Wilt

The unfortunate truth about this destructive tree disease is that the only sure-fire cure for oak wilt is to eliminate the infected trees before they can spread infection to new trees. Sad but true.

This fast-spreading deadly disease can spread via roots and infected wood quicker than you’d believe. The safest option to save the most oaks is to have the diseased trees carefully taken down and properly destroyed.

However, managing oak wilt disease in trees should begin with a careful and correct diagnosis. There are many tree diseases that can affect oak trees, and treatments vary greatly.

If you suspect something is wrong with one of your trees, it is highly recommended that you hire a lawn care service specialist to inspect them.

Due to the high infection and spread rate of this disease, it is also recommended you utilize a professional service for tree removal.

Property owners should be aware that there is a fungicide that has some success in trees suffering from oak wilt.

When disease is spotted early on, a professional can inject this fungicide directly into the tree to help reduce oak wilt symptoms. This fungicide can also be used preventatively when applied before infection.

Again, oak wilt is very serious threat to the beautiful oak trees that we all love so dearly. For diagnosis and treatment you should always seek the help of a professional as soon as possible.

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