How can I tell if a tree is dead or dangerous?

Most dangerous trees give warning signs you can see from the ground: dead or hanging branches, cracks, cavities, fungus, a new lean, or limbs over the roof or wires. A dead tree is easier to spot in the growing season, when it has no new leaves or growth. The catch is that a living tree can be dangerous too. The USDA Forest Service's Tree Owner's Manual puts it in five words: "Healthy trees can fall down."^[1] It adds that a tree may be green and lush and still not be structurally safe.^[1]

Look from the ground, with binoculars for the upper crown, and leave anything closer to a professional.

Warning signs to look for

The manual's advice is to "Inspect trees anytime, but especially after storms",^[1] and to look at the crown, branches, trunk and root area for these common dangers:

• "Broken, dead, or hanging branches"^[1]
• "Cracks, fungi, and cavities"^[1]
• "Weak trunk or branch unions"^[1]
• "Encircling root compressing the trunk", where a flat-sided trunk at the ground level is a good indicator^[1]
• "Recent lean (especially if the soil or grass has lifted on one side)"^[1]

The Virginia Department of Forestry's storm-readiness sheet adds its own list of symptoms to have evaluated: over-maturity or dieback, large cavities, decay or a conjoined trunk, cracks in the trunk or major limbs, damaged roots, bark or trunk, a one-sided or leaning tree, and branches close to utility lines or structures.^[2]

Branch unions deserve a close look. Where two stems or a branch and the trunk meet, the manual's illustration shows that a strong union has bark pushed out at the crotch, while a weak one has bark grown in.^[1] A V-shaped fork with bark squeezed into it is a classic weak point. The Virginia Department of Forestry's poster of common tree-care mistakes warns about "codominant leaders with included bark that split during winds and storms".^[4]

A new lean matters more than an old one. A tree that has grown at an angle for decades has usually adjusted to it. A tree that has started leaning recently, especially with cracked or heaved soil on the opposite side of the lean, may be losing its roots' grip.

Is the tree dead, or just struggling?

In winter many healthy trees look bare, so judge in the growing season if you can.

• New growth. According to the manual, "a dramatic reduction in growth rate may be an indication of poor health",^[1] and this year's branches are typically smaller in diameter and a different color from older wood.^[1] No new shoots at all, across the whole crown, is a bad sign.
• Leaves. The manual suggests looking at the size, color and distribution of the leaves, comparing one section of the crown with another, and inspecting the base of the trunk for damage from rodents or string trimmers.^[1] Leaves that never come out in spring, or brown leaves that hang on through summer, usually point to a dead or dying tree or limb.
• Bark. Bark falling away in sheets, or a trunk that sounds hollow, often means trouble underneath.

Damage at the base is a common cause. The Virginia Department of Forestry's poster of common mistakes makes the point that few trees in yards die of old age; mechanical damage and improper tree care kill more trees than any pests or disease.^[4] Mower scrapes, trenching through roots and soil piled against the trunk all show up years later as dieback.

Two Virginia problems worth knowing

Armillaria root rot. The Virginia Department of Forestry describes its visible sign as clusters of tan or orange gilled honey mushrooms on or near infected trees,^[3] and notes that the mushrooms are present in late summer through October.^[3] It is not a rare disease: "Armillaria root rot is a common contributing factor of oak decline in Virginia."^[3] Decay at the roots is exactly the kind of weakness you cannot see in the crown.

Emerald ash borer. If you have ash trees, watch them. The department lists the signs as bark stripping by woodpeckers hunting for the larvae, wilting foliage and canopy dieback, and D-shaped exit holes in the bark.^[3] "After infestation, trees typically die within three to five years if untreated."^[3] Treatment is time-sensitive, because "when more than 30 percent of the canopy has been lost, treatment may not be successful."^[3]

Dead is not always dangerous

What makes a tree dangerous is what it could hit. A dead tree over the house, driveway, a play area, the street or a power line should come down. A dead tree at the back of a wooded lot, where it can only fall on more woods, can sometimes be left: the Virginia Department of Forestry notes that "Standing dead trees are good habitat for woodpeckers."^[3] An arborist can tell you which situation you are in.

What to note before you call

The Virginia Department of Forestry's advice for a sick tree is to note where you see the symptoms, such as mushrooms at the base, insect exit holes or spots on the leaves, take photos of the whole tree and close-ups of the damage, and record the date, location and number of plants affected.^[5] That record helps an arborist, and helps you compare quotes.

When to call a licensed pro

Call a tree professional for any of the warning signs above, and right away for a fresh crack, a hanging limb over a roof or path, or a new lean with lifted soil. The department's advice before deciding on removal is: "Get a checkup for your trees by an ISA-certified arborist."^[2] For a second opinion, the Virginia Department of Forestry has "certified arborists on staff who can answer questions regarding proper tree care".^[6]

Do not climb or cut a damaged tree yourself. The Virginia Department of Forestry says to use extreme caution when cutting storm-damaged trees, or hire a qualified arborist, tree care professional, or logger,^[9] and the Tree Owner's Manual says: "Never prune trees or branches that are within 10 feet of utility lines."^[1] Virginia law keeps anyone working in a trade from bringing people or equipment within 10 feet of an overhead high voltage line^[8][7] without arrangements with the utility, so if the tree touches or overhangs a wire, call the utility first.

When removal is the answer, what happens when a tree service removes a tree explains the job and what tree removal costs in Virginia explains the price. To keep a sound tree that way, see how often trees near a house should be trimmed.

Browse tree services, find lawn and landscaping businesses in Blacksburg, or see all lawn and landscaping answers.

Describe the tree once and local tree services quote an assessment or removal.