What is oak wilt?

Oak wilt is a fungal disease that attacks the vascular system of oak trees, especially Red (A), or Spanish (B), Oak and Live Oaks (C). Oak wilt disrupts the flow of water and nutrients to the tree’s tissues. It kills quickly. Infected Red Oaks are hit the hardest and can die within four weeks of infection, Live Oaks within six months.

How is oak wilt transmitted?

The disease is passed from one tree to another in a couple of different ways. Oak trees are connected by their root system, once an oak is infected chances are that, without immediate treatment, other trees connected by these root grafts will also be infected. Another way oaks are infected is by insects that carry the spores with them onto fresh wounds on the trees. Wounds can come from pruning, landscaping companies working in the area, utility companies that might be working on the property and, of course, Mother Nature with her spring storms and high winds. Simple pruning paint placed on the wounds as quickly as possible should protect the trees. The most unfortunate and unnecessary source of infection comes from infected, dead trees that are cut down and not disposed of properly.

What is done with the infected trees?

Infected trees that are cut down should either be removed and burnt, or securely covered so that insects do not have the chance to leave their infected home and spread. Most property owners recognize the value of the trees on their property (estimated at 20% or more of the property’s value); unfortunately, most are uneducated as to a) what oak wilt is; b) how to identify the disease; and c) what to do to prevent and/or contain the disease.

How do I identify oak wilt?

We have discussed what oak wilt is, and the danger it imposes, but how does a property owner identify the disease in his or her trees? The simplest method is to look at the leaves. In Live Oak trees the veins running through the leaves become discolored, either red or yellow. Discoloration follows no pattern in the Live Oak it could be in the middle of the tree, the outside, anywhere.

In Red Oaks there tends to be a pattern that goes from the top of the tree to the bottom. It is, however, more difficult to detect in Red Oaks and the pattern on the leaf is different. On Reds the discoloration begins on the tips of the leaves and works its way in. The best time to identify the disease is from March to May.

Who do I contact for an expert assesment?

1. An oak wilt suppression specialist - OakRx will come out for free to evaluate your trees
2. A qualified arborist
3. The Texas Forestry Service, who also provides a free risk assessment.

How can I prevent oak wilt from attacking my trees?

Up to twenty percent of infected trees survive oak wilt without treatment, but the devastation caused by the 80% that do not survive is irreparable. The best method of protection against oak wilt is prevention. Before the disease hits take basic steps to protect one of the Texas Hill Country’s most valuable natural assets, its oak trees. Being educated on the disease is the first step. Know what the disease is and how to look for it.

To prevent the disease there are two accepted methods:1) trenching; and 2) Alamo injections. They have both been proven effective measures against the oak wilt disease, as discussed in the next section, Oak wilt prevention.