How to Inspect Your Trees for Health Issues

Most homeowners do not think much about their trees until something goes wrong — a branch falls, leaves turn brown in July, or mushrooms appear at the base of the trunk. By that point, the problem may have been developing for years. The good news is that many tree health issues show visible warning signs long before they become serious. Learning to read those signs during a simple walk around your yard can help you catch problems early and call in a professional before a manageable issue becomes an expensive emergency.

Start at the Base

Begin your inspection at ground level. The base of a tree reveals a surprising amount about its health:

• Mushrooms and fungal conks: Mushrooms growing at the base or on the trunk are a sign that decay fungi are breaking down wood inside the tree. Some fungal species, like honey mushroom, indicate advanced root rot. Others, like bracket fungi (shelf-like growths on the trunk), signal internal decay. Any mushroom growth on or near a tree warrants a professional assessment.
• Root flare visibility: You should be able to see the root flare — the point where the trunk widens at the base. If the trunk goes straight into the ground like a telephone pole, the tree may be planted too deep or soil and mulch have accumulated. Buried root flares lead to bark decay and girdling roots.
• Soil heaving: Raised or cracked soil on one side of the tree can indicate root failure. The tree may be starting to lean as roots on the opposite side lose their grip.
• Girdling roots: Look for roots that circle the trunk rather than spreading outward. These roots strangle the trunk as both grow, restricting the flow of water and nutrients. Girdling roots are especially common in trees that were container-grown or planted too deep.

Examine the Trunk

The trunk is the tree's structural core, and damage here is often the most consequential:

• Cracks and splits: Vertical cracks can indicate frost damage, internal decay, or structural stress. Horizontal cracks are more serious — they suggest the trunk is under bending stress and may be at risk of failure.
• Cavities: Holes in the trunk where wood has rotted away reduce structural strength. A tree can tolerate some internal decay, but the extent matters. A certified arborist can assess how much sound wood remains using a mallet test or a resistograph.
• Bark abnormalities: Peeling bark, sunken areas (cankers), or oozing sap can indicate disease, boring insect activity, or sunscald damage. Healthy bark should be relatively uniform and intact for the species.
• Leaning: A tree that has always grown at a slight angle is not necessarily a problem — it has developed its wood structure to handle the lean. A tree that has recently begun leaning, especially if the soil is heaving on the opposite side, is a different story and requires immediate attention.

Look at the Canopy

The crown of the tree is where health problems often show up first:

• Dieback: Dead branch tips, especially at the top of the tree or at the ends of major limbs, indicate that the tree is losing its ability to supply water and nutrients to its extremities. Causes include root damage, drought stress, compacted soil, or vascular disease.
• Thin or sparse foliage: Compare the leaf density to other trees of the same species in your neighbourhood. A tree that has noticeably fewer or smaller leaves than its neighbours is stressed.
• Early leaf drop or colour change: Leaves turning colour or dropping in mid-summer usually indicate a problem — drought stress, root damage, or disease.
• Dead branches: Dead wood in the canopy is both a health indicator and a safety hazard. A few small dead twigs are normal, but large dead branches (anything thicker than your wrist) should be removed.

Check Branch Attachments

How branches connect to the trunk matters enormously for structural safety:

• Co-dominant stems: Two trunks or major branches of equal size growing from the same point, often forming a narrow V-shape. This creates a weak attachment that is prone to splitting. If bark is included (growing between and being squeezed by the two stems), the attachment is weaker still.
• Hanging branches: Broken branches caught in the canopy are called hangers. They can fall without warning and should be removed promptly.

When to Call a Professional

A homeowner inspection is valuable, but it has limits. You can spot the visible symptoms; an arborist can diagnose the cause and recommend treatment. Call an arborist if you notice any of the following: mushrooms on the trunk or base, large dead branches, trunk cracks or cavities, a new lean, more than a quarter of the canopy showing dieback, or co-dominant stems with included bark on a large tree near a structure.

An annual tree inspection from a certified arborist costs far less than an emergency removal — and it gives you peace of mind that the trees near your home are safe and healthy.