Dieback, as shown here, is one of the most telling symptoms of tree decline, almost always indicating a soil or root problem. Sometimes this is referred to as stag horning. Photo courtesy of the author.

Many years ago, during a visit to a client’s home, I was informed that another “tree guy” had previously looked at their maple in the front yard. It was fall and there were colorful leaves on the tree, but this other “tree guy” had seen a circle of holes in a horizontal fashion around its trunk. He informed this client that the tree was going to die because of this malady, and that it needed to be taken down soon so the problem did not spread to other trees in the yard.

Because of my training in dendrology and tree pathology and years of working in the field and attending conferences, I had the experience to know this “malady” was a common issue and, in fact, was a symptom of woodpecker damage to maple trees and would not kill the tree.

The fly-by-night practitioner is common in all areas of the country, trying to scare homeowners into cutting trees down unnecessarily. And always quickly, due to the “emergency nature” of the problem. So for you newbies, the one- to 10-years-in-the-field folks, here are a few tree symptoms to consider in an effort to stimulate thinking on trees and tree problems.

Dying is a process
Trees rarely die overnight. Sick and stressed trees can and do send out warning signals, red flags that competent, i.e., experienced, arborists will catch. Stressed trees can begin to decline and die months and sometimes years after common symptoms are observed by a homeowner. Once a tree enters severe decline, no amount of money, wishing or hope will bring it back.

Symptoms
Here is a simple checklist of observable symptoms and red flags that competent arborists should notice rather quickly when inspecting a client’s trees:

• Visible surface roots can point to soil compaction and systemic soil erosion, a major killer of urban trees over time. Without the buffer of adequate mulching, our trees are killed by walking and driving over and compacting the critical root zone, approximately the area below the extent of the branches.
  Mushrooms and conks growing from roots, trunk and limbs point to wood decay and rot that could be hazardous to life and property, and which may require a more comprehensive hazard evaluation.
• Soil built up around the base of a tree, obscuring the taper and buttress roots, is possibly due to construction-related issues or landscapers mulching deeply around trees year after year.
• Black, brown and white staining of bark may point to borer infestations. Though exit holes may be as small as a pinpoint, the inside may have considerable structural damage and girdling of a tree’s trunk, precipitating tree decline and death. Cross-check this by looking closely for very fine wood or bark powder – frass – on a tree’s trunk and buttress roots.
• While localized twig sprouting can point to stress, prolific sprouting – such as occurs after tree topping, extreme crown reduction, over-pruning, lion’s tailing and storm damage – is a last-ditch effort of a tree to stave off starvation.
• Pale, dwarfed and diseased leaves and stunted sprout growth point to tree stress and diseases, such as phytophthora or other bacterial or fungus diseases. But you do not know unless you can compare the leaves observed with the leaves of a healthy tree.
• Lichens and mosses can be like the canary in the coal mine for a tree. With few exceptions (such as the base of aged trees and the limbs of live oaks and maples), this is an indicator of stress in a tree. Healthy trees normally slough off bark before these nonparasitic plants can get a foothold.
• Dieback (the progressive death of branches, usually starting at the top) is one of the most telling symptoms of tree decline, almost always indicating a soil or root problem. Sometimes this is referred to as stag horning. Pruning deadwood every few years without addressing root/soil problems can give tree clients a false sense of security. This dieback in the crown is a symptom of a larger root problem.
• Thinning crowns become perches for birds and the hemiparasitic mistletoe they transport on their undercarriage.
• In the spring, some species of trees, such as the walnut, naturally leaf out late. However, late leafing out can be an indicator of stress and decline, such as girdling roots above and below ground.
• In the fall, some species of trees turn color and/or shed early; sadly, many times early leaf changes are indicators of disease stress and decline.
  Bacterial leaf scorch, spread by leafhoppers and spittlebugs, may appear in stressed and declining trees in late summer or early fall, and can kill a tree within a few years. The leaves will look bronzed over much of the crown, and every year a few branches die back. Oak trees are very prone to this. Treatments are iffy at best.
• Hypoxylon canker attacks trees in severe stress and decline also. Once the white, gray, tan, olive and black lesions appear in crowns and on trunks, branches become very brittle and can fall at any time; once on the trunk, tree death may be within a few weeks to a few months. This phenomenon looks like the tree has shed its bark.
• Competent arborists and arboricultural firms know that tree-climbing spikes not only leave ugly wounds on the trunks and branches of trees, but also can spread infectious diseases such as bacterial slime flux and leaf scorch. Climbing spikes are never worn by professional arborists on live trees!
  Maples, dogwoods, oaks and other species can be inspected in the fall for possible phytophthora symptoms: smaller than usual leaves, short twig internodes, leaves changing color earlier than usual, leaf petioles hanging on maples in the dead of winter or blood-red ooze from a nonspecific bark site.

Conclusion
This is not a comprehensive list of considerations, but in all cases, taking samples of a tree’s symptoms, roots, twigs, etc., and sending them to the local agricultural extension service within your state will get more definite answers to the problems.

W. Jim Cortese is a mostly retired consulting arborist, transitioning to full-time writing. He has been an ISA member since 1977, and is a retired ASCA member and Board Certified Master Arborist (BCMA). He was founder and owner of Cortese Tree Specialists Inc., an accredited, 40-year TCIA member company prior to its sale to The Davey Tree Expert Company in 2013. He also was founder and former CEO of TIPCO (Tree Injection Products Company) Inc., a former TCIA corporate member company, also based in Knoxville.