Tree risk checklist

What this checklist is, and isn’t

It’s a way to write down what you see before you call anyone. The questions follow the owner checklist in the International Society of Arboriculture’s consumer brochure Recognizing Tree Risk (2021), which covers dead and hanging branches, cracks, cavities, mushrooms, construction damage, leaf color and topping [1]. ISA’s own advice is that judging how serious those defects are is a job for a professional arborist [1].

It is not a tree risk assessment. A real assessment is done on site by an arborist who walks around the whole tree, often with tools; see tree risk assessment for what that costs and who does it.

How the result is worked out

Mississippi State University Extension publication P3717 (revised 2025) scores a tree by adding three ratings: how likely a part is to fail, how big that part is, and what it would hit. A total under 4 is low, 4–6 moderate, 7–9 high and over 9 extreme [2]. The checklist keeps those three ideas without the numbers:

• Emergency if a power line is involved or the tree is failing now.
• Get it assessed soon if you ticked a sign of failure in progress (new lean, lifting soil, a crack, a hanger, big dead limbs over a target) and something is under the tree, or three or more defects with a target.
• Get an arborist assessment for any other warning sign: a cavity, conks, root damage, topping, included bark, dieback or branches near wires.
• Low concern if you ticked nothing, or only “something to hit.”

P3717 notes that more than 80% of trees that fail in storms had defects beforehand [2], which is why a defect with a house under it moves up a level.

Numbers that help you answer

• Lean. P3717 rates 15–40° moderate and over 40° high [2]. A lean the tree has always had is less worrying than one that appeared after a storm.
• Root area. 1.5 ft of radius for each inch of trunk diameter [2]. A 20-in Douglas fir has a critical root area 30 ft out from the trunk, so a driveway or sewer trench 15 ft away is inside it. Read more on tree root damage and laminated root rot.
• Cavities. A cavity across more than 30% of the trunk’s circumference is rated high [2].
• Branches. Any branch over 4 in thick with a crack or decay is rated high [2].

What to do next

Never cut or pull branches that touch or hang near a power line; ISA’s brochure is plain on that and on staying away from downed lines [1]. Call the utility (tree removal near power lines). For a tree that is down or coming down, see emergency tree service. For a dead tree, dead tree removal.

If the checklist says “assessed soon,” mark off the area where the tree or limb would land until someone has looked at it. The tree reach calculator shows how far that is.