Diagnosing a Sick Tree in North Texas: A Step-by-Step Guide

A note before you start diagnosing. North Texas trees live hard. Black clay that floods in spring and cracks in August, hundred-degree stretches, spring hail, ice storms, oak wilt in the soil. A sick tree here is usually sick for a boring local reason, not an exotic one. Work the steps below and you will land on the right answer most of the time.

Step 1: read the crown

The crown tells you whether the problem is new or old, sudden or chronic. A tree dying back from the top down, with the branch tips dying first, is having trouble moving water. That means roots, or drought, or something blocking the plumbing. A crown thinning all over, getting sparse year after year, is a chronic problem: compacted soil, a buried root flare, drought stress piling up. Both look bad. They mean different things.

Pay attention to where the damage sits. Dead wood scattered through the crown is usually old storm damage and normal self-pruning, nothing urgent. One whole side of the tree dead or thin points at one side of the root zone: a trench cut for a sewer line, a new driveway, a lightning strike down that side. If the bottom of the crown is fine and the top is dying, check the roots and the water first. Our dead-or-dormant guide covers the seasonal side of this: do not diagnose a tree in February for what might just be winter.

Step 2: read the leaves

Leaves are the dashboard lights, and the pattern matters more than the color. Yellow leaves with green veins on the new growth, worst at the branch tips, is iron chlorosis: the alkaline black clay locks up iron and the tree cannot use it. That is a soil chemistry problem, not a fertilizer shortage, and a bag of fertilizer will not fix it. Uniformly yellow leaves on the older, inner growth is usually nitrogen or just drought. Crispy brown leaf margins in August are heat and drought scorch.

Then there are the eaten ones. Skeletonized leaves and silk webs point at fall webworms or bagworms, both common here and both treatable if you catch them early. Small yellow leaves that never sized up all season can mean root trouble or girdling roots. Leaves dropping green and healthy-looking in summer, after weeks with no rain, is a drought response. The tree is cutting its losses. That is the moment to water, not to panic.

Step 3: read the trunk and bark

Work the trunk next. Shelf mushrooms or conks on the bark mean decay inside the wood, and a tree with conks on the trunk is a structural problem, not a health problem. It does not get better. Black bark peeling off an oak in papery sheets is hypoxylon canker, and it means the tree was already in decline long before the fungus showed up. Hypoxylon is the coroner's report, not the cause of death.

Look for cracks that run deep, bark that lifts in sheets, and wet spots that weep. Check the old wounds: a topping cut from years ago that never closed, a mower scar at the base, a V-shaped fork with bark pinched in the middle. Trees do not heal. They wall off damage, and they can only wall off so much.

Step 4: read the base and the ground

This is where most sick-tree mysteries get solved. Find the root flare, the place where the trunk widens into roots. If the trunk goes into the ground like a telephone pole, the flare is buried, and buried flares grow girdling roots that slowly strangle the tree. A mulch volcano piled against the trunk does the same damage: moisture rot, pests, and roots growing up into the mulch instead of down into the soil.

Look at the ground, too. Soil heaving on one side of the base with a lean that keeps increasing means the root plate is failing, and that tree is one storm away from falling over. A recent trench, new driveway, or grade change inside the drip line explains a decline that started right after the work. Construction damage is slow. It shows up a year or two after the job, when everyone has forgotten the trench. Standing water after every rain drowns roots. Bone-dry cracked clay starves them. Both show up in the crown first.

Step 5: put it together and decide what to do

Now match what you found. Drought stress: deep, infrequent watering out to the drip line, not a daily sprinkle at the trunk. Iron chlorosis: a soil test first, then chelated iron or soil sulfur, not fertilizer. Buried flare or girdling roots: hand-expose the flare, cut the girdling root in the dormant season, and fix the mulch. Storm damage: prune the broken limbs back to sound wood, and do it to standard.

And know when to stop diagnosing and call someone. A big tree over a roof or driveway, conks on the trunk, a lean that keeps getting worse, more than a third of the crown dead, or any oak showing decline between February and June when oak wilt beetles are active: those are professional calls. Here is how we read the warning signs that mean removal, and when in doubt, take the 60-second tree risk check.

The mistakes that waste the diagnosis

A few things people do that make it worse. Spraying a random fungicide from the hardware store when the problem is drought. Fertilizing a stressed tree, which pushes new growth the roots cannot support. Topping the tree to save it, which opens wounds the tree was already too weak to close. And the most common one: ignoring it for a year and hoping it turns around. Trees rarely turn around on their own. Catch the problem early and most of them are fixable. Our trimming page and removal page show what the actual fix looks like.

Common Questions