Is Your Tree Healthy? 5 Checks

You do not need to be an arborist to figure out whether a tree on your property is healthy or in trouble. After 30 years of looking at trees across Middlesex County, I can tell you that most of the signs are visible from the ground if you know where to look. Here is a simple five-point inspection you can do yourself in about 10 minutes, plus a guide for knowing when it is time to call a professional.

1. Check the Canopy

The canopy is the single best indicator of overall tree health. Stand back far enough to see the whole crown and ask yourself these questions:

• Is it full? A healthy tree has a dense, full canopy appropriate for its species. Compare it to other trees of the same type in the neighborhood. If your red oak has a thin, sparse canopy while your neighbor's red oak is thick and lush, something is wrong.
• Are there dead branches? A few small dead twigs in the interior are normal — trees naturally shed interior branches that do not get enough light. Large dead branches in the upper canopy are not normal. If you can see bare, barkless branches sticking up from the top third of the crown, that is a red flag.
• Is dieback progressing from the top down? Top-down dieback is a classic pattern of root problems, vascular disease, or pest infestation (especially emerald ash borer in ash trees). If the top of the tree is bare and the bottom still has leaves, the problem has been developing for years.
• Are the leaves the right size and color? Undersized leaves can indicate nutrient deficiency or root damage. Yellowing between leaf veins (chlorosis) suggests iron or manganese deficiency. Brown, scorched leaf margins in summer can indicate bacterial leaf scorch, salt damage, or drought stress.
• Is there only one side with leaves? A tree with foliage on one side and bare branches on the other has damage or decay affecting one side of the trunk or root system. This creates an unbalanced crown that is vulnerable to wind throw.

I tell homeowners to take a photo of their large trees each June and compare year to year. A gradual decline that is hard to notice in real time becomes obvious when you compare this June's canopy to last June's.

2. Check the Bark

Walk up to the tree and examine the bark from ground level up as far as you can see:

• Normal bark: Every species has its own bark pattern — smooth beech, shaggy hickory, plated oak, peeling birch. Learn what your tree's bark should look like and then look for deviations.
• Cracking and splitting: Vertical cracks that run the length of the trunk can indicate internal decay, frost damage, or lightning strike. A single crack does not necessarily mean the tree is doomed, but deep cracks that expose the inner wood are concerning. Multiple cracks on the same trunk are a serious structural red flag.
• Missing bark: Large patches where bark has fallen off, exposing bare wood underneath, indicate that the cambium (the living layer just under the bark) has died in that area. This can be caused by disease, sunscald, mechanical damage, or construction injury.
• Cankers: Sunken, discolored, or swollen areas on the bark where the tree has tried to wall off an infection. Small cankers on branches are minor. Large cankers on the main trunk that cover more than 25 percent of the circumference can compromise structural integrity.
• Oozing or bleeding: Dark sap or liquid seeping from the bark can indicate bacterial infection, boring insect activity, or internal decay. Alcoholic slime flux (bacterial wetwood) produces a foul-smelling ooze that runs down the trunk. It is common in elms and oaks and is generally not fatal on its own, but it indicates internal stress.

3. Check the Trunk

The trunk is the structural backbone of the tree. Problems here are the most serious because they directly affect whether the tree can hold itself up:

• Cavities: Holes or hollows in the trunk. Small cavities can be stable for decades. Large cavities — especially ones where you can fit your fist inside, or where you can see through the trunk — mean significant structural wood has been lost. The rule of thumb is that if the combined cavity area covers more than one-third of the trunk's circumference at any given height, the tree is at high risk of failure.
• Mushrooms and conks: Fungal fruiting bodies growing directly out of the trunk or at the base of the tree are a major warning sign. By the time you see mushrooms on the outside, the internal decay is extensive. Common species in our area include artist's conk (Ganoderma), honey mushroom at the base, and chicken of the woods on oaks. See our guide on warning signs a tree needs to be removed for details on each.
• Co-dominant stems with included bark: This is a structural defect where two trunks grow from the same point with bark pinched between them instead of a strong branch union. The included bark prevents the stems from fusing together, and the union is much weaker than it looks. In high winds, co-dominant stems split apart. This is the number-one cause of structural tree failure that I see in Chelmsford, Tewksbury, and Burlington. If you can see a dark line or crack where two large trunks meet, have it assessed.

4. Check the Roots

Roots are mostly underground, but you can still see important clues from the surface:

• Root flare: A healthy tree should have a visible flare at the base where the trunk widens into the root system. If the trunk goes straight into the ground like a telephone pole, the tree was planted too deep or soil has been mounded around the base. Buried root flares lead to bark decay and girdling roots, which can slowly strangle the tree over 10 to 20 years.
• Heaving soil: If the soil on one side of the tree is cracking, lifting, or mounded upward, the root plate may be pulling out of the ground. This is a sign of imminent failure and you should keep people away from the fall zone and call us immediately.
• Severed or damaged roots: Visible roots that have been cut by construction, severed by trenching, or crushed by equipment represent lost anchorage and reduced water/nutrient uptake. The effects may not show in the canopy for 2 to 5 years, which is why so many trees die "mysteriously" a few years after nearby construction.
• Circling roots: Roots that wrap around the base of the trunk instead of radiating outward. These eventually compress the bark and strangle the tree's vascular system. Common in trees that were not properly planted from containers. Look for a trunk that is narrower at the base than above it — that is a girdling root compressing the trunk.
• Mushrooms at the base: Clusters of mushrooms growing right at the root flare or from surface roots indicate root and butt rot. Honey mushroom (Armillaria) is the most common culprit in Massachusetts. This is more serious than mushrooms growing in the general area of the lawn.

5. Check the Lean

Not all leans are dangerous. The key is distinguishing between a natural lean and a new, worsening lean:

• Natural lean: A tree that has always grown at an angle, with a curved trunk that compensates to keep the center of gravity over the root zone. The trunk curves to redirect growth upward. The root system has developed to support this lean. This is stable and generally not a concern.
• New lean: A tree that was straight and has recently tilted. The trunk is straight but the whole tree is angled from the base. Soil may be heaving or cracking on the opposite side. This means the root system is failing and the tree could fall. This is an emergency. Call us at (978) 375-2272 or contact our emergency service.
• Worsening lean: An existing lean that is getting more pronounced over time. If you notice the angle has changed from last year, the root system is progressively losing its hold. This tree needs professional assessment soon.

A simple test: look at the soil around the base on the side opposite the lean. If the ground is cracked, heaving, or you can see roots pulling up, that is active root plate failure. Do not stand on the lean side of that tree.

When to Call a Professional

Here is a quick decision guide based on what you found:

• Call immediately (same day): New lean with soil heaving, large split in the trunk, major limb hanging or partially detached, tree rocking in moderate wind
• Call this week: Large dead branches in the upper canopy, mushrooms on the trunk, large cavities, bark falling off large sections, co-dominant stems with visible cracking
• Schedule an assessment (within a month): Gradual canopy thinning, chlorosis, small cankers, minor dieback, circling roots at the base
• Monitor and re-check in 6 months: A few small dead interior branches, minor bark damage, slight natural lean that has not changed

For situations where you need a diagnostic assessment of a tree's health — figuring out exactly what disease or pest is affecting it and whether treatment can save it — an ISA-certified arborist who specializes in tree health care is the right call. For situations where the tree clearly needs to come down or needs pruning to address hazardous deadwood, that is what we do every day.

Get a Free Assessment

McDonald Tree Service has been assessing trees across Middlesex County since 1995. If you have a tree you are worried about, call (978) 375-2272. I will come out, walk your property, and give you an honest assessment — whether the tree is fine, needs monitoring, needs pruning, or needs to come down. No charge, no obligation, no sales pressure. We serve Billerica, Chelmsford, Tewksbury, Lowell, Wilmington, Burlington, Bedford, Carlisle, Dracut, Westford, Andover, Woburn, and Lexington.