6 min read
The scratch test
The quickest check anybody can do. Scratch a small patch of bark on a twig with a thumbnail or a pocket knife. Green and moist underneath means that part is alive. Brown, dry and brittle means it is not.
Do it in several places. Different sides, different heights.
Green low and brown high means the tree is failing from the top down. That is often a root problem.
Brown on one side and green on the other usually means damage to that side. Sometimes from a trench dug years ago, sometimes from a lightning strike.
Signs it is dying
- Leafing out later each spring, thinner each year
- Dead branches through the upper canopy, called stag-heading
- Bark falling away in sheets with nothing regrowing underneath
- Sprouts coming out of the base or the lower trunk, which is often a stress response
- Fine twigs that snap dry rather than bend
A tree can be declining for years and still be perfectly safe. Declining is not the same as dangerous.
Signs it is dangerous, which is different
These are the ones that move a tree up the list regardless of how green it looks:
- Fungus at the base. Mushrooms or shelf fungus growing out of the root flare usually means the wood inside is already rotten. The canopy can look perfect while the base is hollow.
- A vertical crack or seam in the trunk. Especially one that opens and closes as the tree moves.
- Soil heaving on one side of the base. The root plate is lifting. This is a tree in the process of falling over.
- A new lean. Trees that grew leaning are usually fine. A tree that has recently started leaning is not.
- A tight V-fork with bark growing inward. Included bark. This is where big trees split down the middle.
- A cavity taking most of the trunk width. Trees compartmentalise decay well and a small hollow is not automatically fatal, but there is a point where too little sound wood is left.
Things that look terrible and usually are not
- Yellow leaves with green veins. Chlorosis, common in our alkaline soil, and treatable.
- Leaf spots and blotches in a wet spring. Mostly cosmetic. The tree releafs.
- Bumps on hackberry leaves. Nipple gall. Ugly, harmless.
- Early leaf drop in a drought. A survival response, not a death sentence.
- Bark splitting on a young trunk in winter. Frost crack. Usually seals over.
The question that actually decides it
Not "is it dying" but "what does it hit if it fails". A hollow tree at the back of ten acres can stand for years and hurt nobody. The same tree twenty feet from a bedroom is a different decision entirely.
Two things set the priority: how likely it is to fail, and what is underneath it. A tree with one warning sign over a house outranks a tree with three warning signs over an empty field.
When to call somebody today
Same day, not next week, if you see any of these:
- A limb hanging in the canopy, still attached but broken. A hanger drops without warning.
- Soil lifting at the base after heavy rain or high wind
- A crack that has opened since you last looked
- Any part of the tree in contact with a power line
- A tree leaning further than it was last week