Published May 22, 2026
Trees give warning signs before they fail — but those signs are easy to miss if you do not know what to look for. The seven indicators below are visible from the ground during a simple walk-around of any large tree on your property. Finding one or more of these is not necessarily an emergency, but it is a reason to schedule an arborist assessment before the next storm season.
1. Cracks in the Main Stem or Scaffold Branches
Cracks that run vertically through the stem or that separate co-dominant stems (branch unions where both stems are roughly equal in diameter) are structural indicators. Included bark — bark tissue trapped between two co-dominant stems — creates a crack that widens as the stems grow. When you can see daylight between two major stems, or when a crack runs more than 6 inches along the stem, that tree needs assessment. Bradford pears are the most common species exhibiting this in Upstate SC, but co-dominant stem cracks occur in oaks, maples, and sweetgums as well.
2. Fungal Conks or Bracket Fungi on the Trunk
Fungal conks — shelf-like projections growing from the bark of the trunk — are the fruiting bodies of decay fungi inside the tree. Conks on the lower trunk indicate advanced wood decay at the structural base of the tree. Conks on the upper scaffold branches indicate decay in those limbs. The presence of a conk means the decay column is already significant — by the time a conk is visible externally, substantial internal wood volume has been lost. Common decay fungi in Upstate SC include Ganoderma (varnished shelf appearance, typically near the base) and various bracket fungi on upper stems. Any conk on a tree near a structure, vehicle area, or foot traffic zone warrants an immediate assessment.
3. Soil Heaving or Mound on One Side of the Root Flare
A raised mound of soil on one side of the base of a tree that was not there before — or that has been slowly growing — indicates root plate movement. This is a sign that the tree is beginning to lean from root failure, not from gradual growth lean. Root plate movement is one of the most serious structural warning signs because complete root plate failure happens suddenly. If you notice a new raised area of soil on the upwind side of a leaning tree, or if the soil appears to be cracking around the base, call for an assessment the same day.
4. Dead Branches in the Crown
A tree with dead branches in the crown — especially large dead branches in the upper canopy — is a fall hazard. Dead wood loses structural integrity over time as it dries and becomes brittle. Large dead branches (greater than 4 inches diameter) at height can fall without warning, particularly during wind events. The tree does not need to be dying overall — a single large dead scaffold branch in an otherwise healthy oak is still a significant hazard if it is over a structure, a patio, or a play area. Annual dead wood removal is the appropriate response for large trees in occupied areas.
5. Leaning That Has Changed
All trees lean to some degree — gradual lean toward light is normal. The concerning pattern is lean that has changed, particularly lean that has increased recently. If a tree that was vertical last year is now visibly off-vertical, or if a previously leaning tree has increased its lean angle, the cause needs investigation. Sudden lean changes indicate root plate movement or internal failure. Gradual lean increase can indicate progressive root loss, soil erosion, or root decay. Check by looking at photos of the tree from prior years — this is one of the few cases where old photos are genuinely useful for tree assessment.
6. Cavities or Hollow Areas in the Trunk
Cavities — open hollow areas in the trunk — indicate decay has progressed to the point of complete wood loss in that section. The structural concern depends on the location, size, and remaining wall thickness. A small cavity in the lower trunk with thin remaining walls is more concerning than a large cavity in the upper crown with substantial sound wood surrounding it. As a general rule: if you can insert your arm into the cavity, or if the cavity occupies more than one-third of the trunk circumference at that point, it warrants professional assessment. Do not attempt to fill cavities with concrete or foam — this does not strengthen the tree and can accelerate decay by trapping moisture.
7. Mushrooms at the Base After Rain
Honey-colored mushrooms clustered at the base of a tree, particularly after rain in late summer or fall, are the classic sign of Armillaria root rot. These mushrooms are the fruiting bodies of a fungus that is actively decaying the root crown and structural roots below ground. The crown may look completely healthy while the root system is being compromised. Any large tree — especially a water oak, red maple, or stressed pine — producing mushrooms at its base should be assessed for root system integrity. See the Armillaria Root Rot guide for full identification details.
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