Do not wound or prune oaks from February through June, and paint every wound on an oak right away, any time of year: "any kind of paint will accomplish this task" (Texas A&M Forest Service). Clearing is one of the ways oaks get wounded, so plan oak-side work for the safer months and keep machines off the trees.
How oak wilt spreads
Oak wilt is a fungal disease. It spreads two ways:
- Overland, by beetles. Fungal mats form on infected red oaks. Sap-feeding beetles visit the mats, then fly to fresh wounds on healthy oaks and infect them.
- Underground, by roots. Once one tree is infected, the fungus moves through connected roots to its neighbors.
The Texas A&M Forest Service names land clearing, including cedar clearing, as one of the ways oaks get the fresh wounds that let the beetles in (Texas A&M Forest Service).
Which oaks are at risk
- Red oaks such as Spanish oak, Shumard oak and blackjack oak are "extremely susceptible".
- Live oaks are "intermediate in susceptibility" but "are most seriously affected", because their roots connect and the disease runs through a whole motte.
Both points come from the Texas A&M Forest Service and USDA Forest Service manual (Identify and Manage Oak Wilt in Texas).
The February to June rule
The Texas A&M Forest Service advises against pruning or wounding oaks from February through June, and calls it "especially critical" in the more than 76 Texas counties affected by oak wilt (Texas A&M Forest Service). That is when beetles and fungal mats are most active.
For land clearing, that means planning work right around oaks for July through January where possible, and taking extra care if spring work cannot be avoided.
Paint every wound
"Always cover or paint wounds on oaks, no matter the time of the year. ... Any kind of paint will accomplish this task" (Texas A&M Forest Service). The manual says wounds should be "treated immediately with a wound or latex paint" (Identify and Manage Oak Wilt).
On a clearing job that means paint goes on the truck, and any scraped bark or broken limb on an oak gets painted on the spot.
San Antonio's oak rules
Inside the City of San Antonio and its ETJ, the tree ordinance FAQ says to "minimize pruning oak trees between February 1 and July 1", and that "all cuts and wounds on oak trees shall be painted" no more than 30 minutes after they are made (City of San Antonio). Note the city's window runs to July 1.
Clearing around oaks: a checklist
- Mark every oak you want kept before work starts.
- Plan oak-side work for July through January where you can.
- Keep machines and brush piles off the root zones and away from the trunks.
- Never pile and burn brush under or beside an oak.
- Carry paint and use it on any wound, straight away.
- Do not haul or stack green red oak firewood next to healthy oaks. The manual advises drying firewood "for at least one full year".
Containment work on an existing oak wilt center, such as trenches at least 4 feet deep and at least 100 feet beyond the symptomatic trees (Identify and Manage Oak Wilt), is specialist work. Ask the Texas A&M Forest Service for guidance if you suspect oak wilt.
Common questions
When is it safe to clear around oaks?
The Texas A&M Forest Service advises avoiding wounds from February through June. July through January is safer, and any wound should still be painted.
What kind of paint do I use on an oak wound?
The Texas A&M Forest Service says any kind of paint works. The manual mentions wound or latex paint, applied immediately.
Are live oaks or red oaks more at risk?
Red oaks are extremely susceptible. Live oaks are less susceptible but suffer the most, because their connected roots spread the disease through a whole group.
Does clearing cedar spread oak wilt?
Clearing can wound oaks, and fresh wounds let the beetles in. Careful clearing outside the spring window, with wounds painted, keeps the risk down.
Talk to us about your land
Every piece of land is different. Call (830) 328-3684 or send the form for a free estimate. See our land clearing service.
