My Tree Looks Diseased in Fort Worth — What Is Actually Wrong?

Start with the pattern, not the leaf

A tree that “looks diseased” is telling you something, but the useful information is in the pattern — where the symptoms started, how fast they moved, and whether neighbouring trees are affected. Four conditions cover most of what we diagnose in Fort Worth.

1. Oak wilt — the one that is urgent

A vascular fungus. In red oaks the crown browns over a few weeks in late spring or summer and the tree dies, often with fungal mats under cracked bark. In live oaks the sign is veinal chlorosis: the leaf veins turn yellow or brown while the tissue between them stays green — the reverse of iron chlorosis, and worth learning to tell apart.

The tell is that it moves between trees. Oaks share root grafts, and an infection centre expands outward through a group. Fast decline spreading tree to tree is a call-today situation, because the response is trenching to sever root connections and that only works ahead of the front.

2. Iron chlorosis — common and fixable

Yellow leaves with green veins. Fort Worth soil runs pH 7.8 to 8.3 and at that alkalinity iron is locked up. It is a soil chemistry problem, not a pathogen, it does not spread, and chelated iron corrects it. Red maple, pin oak and sweetgum suffer worst; they are poor species choices for this soil.

3. Hypoxylon canker — a symptom of drought stress

Bark sloughs off in patches revealing a grey-brown to black crust underneath, usually on an oak that has been struggling for a year or more. Hypoxylon is opportunistic: it colonises trees already failing from drought, root damage or construction injury. By the time the crust is visible the tree is rarely recoverable, and a hypoxylon tree over a target should be assessed for removal.

4. Root and collar rot — hidden at the base

Thinning canopy, small leaves, general decline with no obvious cause. Look at the base: is the root flare visible, or does the trunk go into the soil like a post? A buried flare stays wet and rots. Mushrooms or shelf fungus at the base mean established decay. This is the most under-diagnosed problem in urban trees and often the most fixable — sometimes with a shovel.

What not to do

Do not fertilise a sick tree reflexively. Unless a soil test shows a deficiency, fertiliser does nothing for disease and the nitrogen pushes soft growth a stressed tree cannot support. Do not prune oaks between February 1 and June 30 — that is how oak wilt gets in. And do not let anyone quote a removal from the kerb.

Get it identified

These four look broadly similar from a distance and need completely different responses: trenching, soil treatment, removal, or a shovel and an afternoon. Our Fort Worth diagnosis visit is free, and we will tell you if the answer is “nothing — water it”.