Before you cut an oak in Fort Worth

Two separate things apply to an oak here. The city's ordinance treats post oak and blackjack oak as significant at 18 inches across, a lower mark than other protected trees. And Texas A&M Forest Service wants no fresh wounds on any oak from February through June, because of oak wilt. Check both before you agree on a date with anyone.

Why post oaks get special treatment

Much of east Fort Worth was once the Eastern Cross Timbers, a hardwood forest of post oak, blackjack oak and cedar elm so dense it was known as the "Cast Iron Forest". The city's tree guide says many of these trees are over 150 years old, and most of the undeveloped remainder lies east of Loop 820. It also finds them on sandy soil in the northwest and Lake Worth area, in older neighborhoods there and in the east, and farther east in the area south of Loop 820. Post oaks turn up more often as you head north toward Keller and Roanoke.

The guide says these two oaks "are much less tolerant of development activities than most other tree species", and are not readily available commercially. The Fort Worth Report describes them as "extremely hard" to breed. A 150-year-old tree cannot be replaced from a nursery.

What the ordinance says about them

• Post oaks and blackjack oaks at 18 inches across, or 56.55 inches around, are significant trees and "can only be removed by permit" (Section 6.302(j)(5)).
• The city's application says trees at that size need an Urban Forestry Permit, not the simpler form.
• On property being developed, at least 50 percent of the post and blackjack canopy must stay, against 25 percent for other protected species (Section 6.302(j)(4)).
• If one is removed under the keep-more-canopy option, the canopy kept has to be post or blackjack as well.

Not sure what you have? The guide does not teach identification, so ask an arborist, or ask the Tarrant County AgriLife Extension office at (817) 884-1945 whether it can help. The permit page covers the rest of the rules and who to ask. If you plan to build or grade near one, raise it with Urban Forestry early.

Which oaks are likely near you

Is oak wilt in Tarrant County?

We could not confirm that either way. Federal forest health reports say oak wilt occurs in 76 documented Texas counties, "mostly counties west of I-35 from Dallas to San Antonio across I-20 to Lubbock". The Forest Service's oak wilt site has county maps, and we did not find one for Tarrant among them. There is one for Parker County, next door, updated 2026. It calls itself only "a general reference for the potential presence of oak wilt". Its highlighted spots had dead trees, and oak wilt "may or may not be currently present" there. A missing map is no all-clear. The precautions cost little, so treat your oaks as if it could reach them.

The calendar

The Forest Service's brochure sets it out. No wounding from February through June, and that includes pruning. Deep midwinter cold and extended heat later in summer are the lowest-risk times to cut. Whatever the month, cuts, fresh stumps and damaged surface roots get wound or latex paint right away. As a 2018 release puts it, "A wound is created any time bark is removed and wood is exposed."

Fort Worth's storm dates do not respect this. Storms in April and June fall inside the window, so a storm-broken oak is a case where safety comes first and the wound gets painted as soon as it is safe. The storm damage page has the order of things.

Why the species matters

Note that post and blackjack, so often lumped together in the city's rules, sit in different rows here. The Forest Service page gives root spread an average of 75 feet a year.

If you think you have it

Symptoms are only clues, and the brochure recommends lab confirmation. The 2018 release points to the Texas A&M Plant Disease Diagnostic Clinic and to your local municipal forester, which here means Forestry for city trees. The brochure wants a red oak that dies in late summer or fall taken down soon after it is found, then burned, chipped or buried. The usual way to protect live oaks is a trench, 4 feet deep or more, placed 100 feet or more past the trees showing symptoms, though it is "not 100%" effective. Trenching is digging, so state notice law applies. Fungicide injection does not stop root spread and is unlikely to work once symptoms pass 30 percent of the crown.

Ask whoever is cutting

What date will you do this? Will you paint the cuts and stump as soon as they are made? Where is the wood going, given that unseasoned wood from a sick red oak can carry the fungus? If someone in April says timing does not matter, get another opinion. The brochure's firewood advice is to buy local wood dried for at least one full year. More is on the questions page.