Oak wilt is one of the most destructive tree diseases in Texas, and it's spreading through Collin County. If you have live oaks or red oaks on your property in Wylie, Allen, McKinney, Plano, or the surrounding area, understanding oak wilt — and how to prevent it — is essential.

Oak wilt is a fatal fungal disease caused by Bretziella fagacearum (formerly Ceratocystis fagacearum). It attacks the water-conducting system of oak trees, causing them to wilt and die. There is no cure — once a tree is infected, it will die.

Oak wilt affects all oak species, but the rate of decline varies:

• Red oaks (including Shumard oak) die within 3–6 weeks of infection. They are the most susceptible species.
• Live oaks decline more slowly — typically over 1–6 months — but are equally fatal. Live oaks also spread the disease through root grafts to neighboring trees.
• Post oaks and white oaks are less susceptible but can still be infected.

Oak wilt spreads through two primary pathways:

1. Sap-feeding beetles. Nitidulid beetles (picnic beetles) are attracted to fresh oak wounds — pruning cuts, storm damage, construction wounds. If they've previously visited an infected tree, they carry the fungal spores and deposit them in the fresh wound. This is why pruning oaks between February and June is so dangerous — the beetles are most active during this period.

2. Root grafts. Live oaks in close proximity often develop root grafts — underground connections between root systems. Once one tree in a grove is infected, the disease can spread through these connections to neighboring trees, creating expanding "infection centers" that can kill dozens of trees.

Red oak symptoms:

• Rapid wilting and browning of leaves, starting at the tips and margins
• Leaves may turn brown while still attached to the tree
• Entire tree can die within 3–6 weeks

Live oak symptoms:

• Yellowing leaves with green veins (veinal necrosis)
• Leaf drop, often starting in the upper canopy
• Decline over 1–6 months
• Fungal mats may form under the bark of recently dead trees (these are the source of spores for beetle transmission)

The single most important thing Collin County homeowners can do to prevent oak wilt is never prune live oaks or red oaks between February and June.

This is not a suggestion — it's the primary prevention measure recommended by the Texas A&M Forest Service. The beetles that carry oak wilt spores are most active during this period, and fresh pruning wounds are the primary infection pathway.

If you must prune oaks during the growing season (storm damage, hazardous limbs), seal every wound immediately with pruning paint or latex paint. Don't wait — seal within minutes of making the cut.

1. Don't prune the tree. Pruning an infected tree creates wounds that can spread spores.

2. Call a professional immediately. Oak wilt diagnosis requires an experienced eye — symptoms can be confused with other conditions. Tree Crew can assess your trees and help you determine whether oak wilt is the cause.

3. Consider trenching. If oak wilt is confirmed, trenching to sever root connections to neighboring trees can prevent spread. This should be done before removing the infected tree.

4. Remove infected trees promptly. Infected red oaks should be removed quickly — they can produce fungal mats that serve as a source of beetle transmission. Infected live oaks should also be removed, with proper wood disposal.

5. Dispose of wood properly. Infected wood must be chipped, burned, or buried. Never leave infected wood in piles where beetles can access it.

The best protection against oak wilt is prevention:

• Never prune oaks February–June
• Seal all wounds immediately if pruning is necessary during the growing season
• Avoid wounding oak roots during construction or landscaping
• Monitor your trees for early symptoms — early detection gives you more options

Tree Crew has 27 years of experience with oak wilt in Collin County and throughout the DFW area. Call (972) 999-3627 to schedule an oak wilt assessment.