Why Oak Trees Are Dying Around Tyler

Thinning crown, peeling bark, brown leaves that won't drop? Here's how hypoxylon canker, post oak decline and oak wilt differ, and what to do next.

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Oaks around Tyler rarely die from one cause. Drought, heat or root damage weakens them, then secondary problems like hypoxylon canker move in.

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Cary Sims, an AgriLife Extension agent in Angelina County, wrote for KLTV in July 2026 that trees "rarely die overnight" and that drought, root damage, lightning, insects and disease "can all become part of the same chain of events." Telling the links apart decides whether you water, wait, or call for a removal.

Four problems that look alike

	What you see	Spreads to other oaks?	Outlook
Hypoxylon canker	Thinning crown, dying branches, then bark falling off in patches to show tan, olive-green or reddish-brown powder that later turns black and hard	No. Texas A&M Forest Service says it doesn't spread tree to tree; its spores are already common	Once it's active, the tree will likely die
Post oak decline	Leaves yellow, spot and turn brown but stay on the tree	Not as a single disease; drought starts it, then cankers, root rot and borers follow	By the time symptoms show, the tree is already dead, the Texas Plant Diagnostic Center's lead diagnostician told Texas Farm Bureau
Oak wilt	A fungus disables the tree's water system; red oaks can die fast	Yes: by beetles to fresh wounds, and through live oak roots	Depends on early, correct diagnosis
Drought, heat or root stress	Yellowing, thinning, more limbs dropping than usual	No	The Forest Service's main defense is watering during drought

The table is a starting point, not a diagnosis. The steps below say who can tell you for sure.

Hypoxylon canker: the one East Texas agents watch for

Sims called hypoxylon canker "one of the most concerning problems I see in stressed East Texas trees." Here's what Texas A&M Forest Service says about it:

It's an opportunist. The fungus lives in the inner bark of many healthy trees without harming them. It invades the sapwood only after a tree is weakened.
Stress opens the door. The Forest Service lists drought, heat, saturated soil, fill dirt, soil compaction, digging in the root zone, removing topsoil, herbicide injury and overcrowding, among others. Activity usually increases during prolonged drought.
The spores mean it's over. By the time the powdery patches show on the trunk, the tree is dead. In four to eight weeks they turn dark and tar-like, and after several months they go silver-gray.
It isn't picky. All oaks are likely susceptible, and elm, pecan, hickory, sycamore and maple can be infected too.

There is no cure. The Forest Service recommends watering during drought when a tree is near a water source, and protecting roots around construction.

Post oaks and the drought years

Post oaks took a hit in the latest federal-state forest survey. The 2025 Forest Health Highlights for Texas describe widespread post oak decline in the drought, worst among older trees.

The pattern isn't new. In 2016, Texas Farm Bureau reported on rapid post oak decline across the state. Texas A&M AgriLife forest pathologist David Appel traced it to the 2011 drought and to years of swinging between wet springs and hot, dry summers. He said oak wilt was not the cause. His tips for yard trees: post oaks don't like "wet feet," so keep turf and its watering away from the trunk. If a post oak browns out, wait until the next spring to see whether it leafs out before you remove it.

Could it be oak wilt?

Oak wilt is the one of the four that spreads. Texas A&M Forest Service counts 76 Texas counties with confirmed cases, with epidemic losses in Central and West Texas. All oaks can be infected. Red oaks grow fungal mats that sap beetles carry to fresh wounds. Live oaks share root systems that spread the fungus about 75 feet a year on average.

We found no published confirmation of oak wilt in Smith County. Prevention is cheap anyway: keep saws off oaks from February through June, and put a coat of paint on any new oak wound whatever the month. Tree trimming timing and the Tyler tree rules guide cover both.

What to do about a sick oak

Look closely in late summer. Sims recommends walking your property in August and looking up for dead branches, thinning crowns, odd leaf color, loose bark and insect signs. He also says to think back: a driveway, pool or patio built near a tree months ago can be the cause.
Get a diagnosis from someone with nothing to sell. Sims suggests Texas A&M Forest Service foresters as a first call. In Tyler, the Smith County AgriLife Extension office is at 1517 W. Front St., Suite 116 (903-590-2980). Tyler Parks and Recreation runs an Ask the Arborist line at (903) 531-1370. See arborist vs. tree service for who does what.
Water if it's drought stress. That's the Forest Service's main prevention step for hypoxylon.
Remove a dead oak near a target soon. The Forest Service says hypoxylon-killed trees that could fall on homes, roads, fences or power lines should come out as soon as possible. Our warning signs checklist helps you judge the risk.

What removing a dead oak costs

HomeAdvisor puts oak removal at about $200 to $2,000 nationally (checked October 2026). For a hypoxylon-killed oak, ask whether the company will use a bucket truck or lift instead of a climber, as the Forest Service advises; the equipment affects the price. The Tyler tree removal cost guide lists the add-ons, and tree removal in Tyler covers permits and hauling. Back to the Tyler tree service home page.

Common questions

Can hypoxylon canker be cured?

No. Texas A&M Forest Service says there is no known control for hypoxylon canker other than keeping trees vigorous, and that once the fungus actively infects a tree, the tree will likely die. Watering during drought and protecting roots from construction damage are the prevention steps it lists.

Why are so many oak trees dying in Texas?

Mostly stress. The 2025 Forest Health Highlights report found widespread post oak decline during drought, with older trees the most susceptible. A Texas A&M AgriLife forest pathologist has described a 'perfect storm' of drought and weather extremes that weakens oaks before canker fungi, root rot and borers finish them.

Can a dying oak tree be saved?

Sometimes, if the cause is drought or root stress and it's caught early. A tree with visible hypoxylon spores is already dead, according to Texas A&M Forest Service. For a post oak that browned out, an AgriLife pathologist's advice was to wait until the next spring to see if it leafs out.

Is it safe to climb an oak killed by hypoxylon?

No. Texas A&M Forest Service says it's very dangerous to climb trees killed by hypoxylon canker, because the fungus decays the wood so fast it may not hold a climber. It recommends bucket trucks or other lifts. Ask any company how it plans to take the tree down.

Can I burn or keep firewood from a hypoxylon tree?

Texas A&M Forest Service says infected firewood isn't considered a source of new infections, and the fungus doesn't spread from tree to tree. Oak wilt is different; see the City of Tyler rules guide on this site for how to handle red oak wood.

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Last updated 2026-10-24