Co-dominant leaders are two or more stems emerging from the same area of a tree’s trunk, an occurrence that commonly results in compressed bark and trunk tissue, severe cracks, and the eventual development of heartwood decay. Photos by John C. Fech
Trees can provide significant functional and aesthetic value on a golf course. The shade, structure and beauty they lend are an essential factor in the overall enjoyment of golfers and visitors alike. Keeping trees healthy requires following best management practices for vigor, and integrated pest management techniques for pest control. When things don’t go according to plan, however, most situations will call for malady diagnosis, otherwise referred to as “triage.”
A main difference between caring for herbaceous/grassy plants vs. caring for woody plants is that it’s much easier to examine the entire turfgrass plant than, say, the entire oak tree. Not being able to see roughly half the tree’s tissues presents an obvious limitation, and it’s the reason I sometimes lament being an arborist. If I were a carpet installer or an orthopedic surgeon, I’d at least be able to look at the full space or subject in front of me — that’s not possible with the roots of a problematic tree. (Oh, sure, you could use an air spade, but that’s pretty drastic and invasive to the tree. Not my favorite technique.)
Alas, simply figuring out what’s wrong with a particular tree or set of trees can be quite challenging, if not outright daunting. On top of that, each tree species has its own set of problems and often produces different symptoms at various times of the year. The following step-by-step guide will help you determine the causal agent(s) responsible for the current status of trees and other woody plants on your golf course. Keep in mind that, as with many other operational diagnostic approaches, triage doesn’t follow a cookbook recipe — there can be a great deal of give and take or “three steps forward, two steps back.”
1. Establish the basics
ID the tree. The industry standard for tree identification is the book “Manual of Woody Landscape Plants” by Michael Dirr. You want to be able to identify at least the genus of the tree in question. Crataegus or hawthorn is nice, but Crataegus phaenopyrum would be better. Why? Just as certain turf cultivars are resistant to rust or leaf spot, certain species or cultivars of trees are resistant as well. Also, given that most reference books are categorized by tree species, you’ll find it handy to instantly be able to jump to the right place.
Look for normality vs. abnormality. In Mel Brooks’ classic movie “Young Frankenstein,” Dr. Frankenstein (Gene Wilder) asks Igor (Marty Feldman) what kind of brain he used in the experiment. “Abby,” replies Igor, followed a few seconds later by “Normal.” The doctor answered in astonishment, “Are you saying that I put an abnormal brain into a 7 1/2-foot-long, 54-inch-wide gorilla?” The point is that even though employing what he had on hand in the lab may have been convenient for Igor, in the end, the experiment yielded unintended results because Igor didn’t pay attention to simple details of normal vs. abnormal.
Knowing the difference between what the tree is supposed to look like “normally” and what it might look like if it were diseased or insect-infested is a necessary element of triage. Is the tree supposed to bend like that? Are the leaves supposed to be green and white, or just green? Is the bark supposed to peel off, or should it all be tightly attached to the sapwood? I’ve heard that U.S. Treasury agents master a similar technique in their field to tell the difference between real money and counterfeit money — they get to know the real stuff so well that a fake $20 bill becomes a cinch to detect.
2. Look for classic symptoms
Studying the classics in literature — “Homer,” “War and Peace,” “Paradise Lost” — is a cornerstone in the shaping of young minds. Familiarity with the classic symptoms or easy-to-spot clues associated with certain tree ailments is just as valuable in triage.
Foliar insects. Damage commonly appears as round, serpentine or blob-like holes in leaves. Leaves may look speckled or “peppered,” as if stuck with pinpricks. A simple 10× magnifying hand lens can help you see such small marks on a leaf.
Foliar diseases. Many tree diseases show up in a similar pattern to turf diseases, such as brown patch and dollar spot. Distinct ovals and round spots are typically symptoms of leaf disease. Other diseases may appear as an overall blighting, especially if the stems are also disfigured.
If planted too deep, a tree won’t develop the healthy even and stout root flare, which was the case with the tree shown here. This inhibits the tree’s structural integrity.
Deep planting. A trunk that doesn’t widen as it enters the soil to create a flare is often a telltale sign of deep planting. In extreme situations, the tree’s lowest branches arise out of the soil rather than above ground.
Topping. A distinct difference in size between branch tissues from one year to the next may signal that a tree has been “topped,” which is when most or all of the stems have been removed at the same location within the canopy to control height. The unfortunate result is the production of fast but weak growth from imbedded buds. Topping allows entrance of decay organisms as well as growth that often breaks in storms.
Co-dominant leaders. Trees sometimes develop two or three main leaders. When this occurs, the usual outcome is compressed bark and trunk tissue, severe cracks, and the eventual emergence of heartwood decay.
Improper mulch depth, placement or type. The cardinal sin of mulching is too much and too close to the trunk. Mulching is a root treatment, not a trunk treatment — as such, it should be placed 2 to 3 inches deep, starting 6 inches away from the trunk and extending as far into the golfscape as is practical. Injury to the root plate often occurs from too much or too little mulch.
Borers. Holes in the trunk and lower limbs are the most noticeable indicators of borers, but a few holes here and there don’t mean a tree has a major borer problem. Many holes, lots of sawdust-like frass and leafless stems are symptoms to be concerned about.
Decay. Soft and punky wood at the root plate, main trunk and branch-removal sites can be serious. Checking the softness of the wood with a screwdriver or golf club shaft is a good way to determine whether excessive decay exists.
Cankers. These oval-shaped, sunken or raised lesions vary in size from an inch to 6 inches and are usually darker or lighter in color than the balance of the stem tissue. Cankers are serious degraders of the conductive vessels of a tree.
Stem-girdling roots. Sometimes visible, sometimes not, wayward roots grow around the trunk instead of outward from it. As girdling roots expand in diameter, they impinge on the trunk tissue and other roots, causing a restriction of the rate of movement of water and nutrients in the tree.
3. Dig into the past
The history of the tree site is important in triage, especially if none of the classic symptoms are present. It’s worthwhile to investigate matters of the past related to weather events, the movement, removal or addition of soil, previous site use, and the performance of any former trees that needed to be removed.
How does one go about learning the history of the site surrounding a particular tree? The same way you’d find out about any other historical element on the course: Ask the people who have worked at the facility the longest, ask other superintendents, and ask neighboring property owners. Look in the files for reconstruction plans. Visit with industry and manufacturer representatives who may have worked on the course, such as irrigation installers. When in the midst of triage, even small bits of information can be helpful.
4. Inventory the here and now
Many current factors can be equally as influential in a tree’s condition as the history of the site. The triage process involves moving from the general to the specific, and, as you do so, you should consider each of the following categories.
Low and high sites. These areas tend to be where soil has been moved, deposited or blown away over time. Low sites can be places where water tends to remain for days; high sites can be drier than other spots on the course.
Herbicide applications. Revisit your records for both pre-emergence and post-emergence applications. Correlations are always possible. Consider sublethal and less-than-full-dose treatments as well.
Irrigation applications. Most trees need less than half the amount of supplemental water that turf needs. If the tree in question is co-located among mid- to high-input turf, it may be getting too much water, which tends to deprive roots of oxygen. Trees located in rough or out-of-bounds areas may face the opposite predicament.
Trunk injuries. Upset golfers and Mother Nature can inflict cracks and bark injuries that are difficult for a tree to recover from. Up-close inspection will normally reveal the evidence of any recent physical damage.
Compaction. Just as with turf, compressed soil particles exclude soil oxygen and decrease lateral and vertical movement of roots. These factors have a compounding effect on nutrient uptake.
Fertilization. Like water need, the requirement for fertilizer is also generally less. If trees and turf are fertilized at the same rate, the trees tend to become more herbaceous than is desirable, and more susceptible to pests. Nutrient deficiencies can also be an existing limiting factor, in terms of both micro- and macronutrients.
Weather. Weather extremes can be the cause of many maladies for trees on a golf course. Cold winters, hot summers, overly humid conditions and windy stretches of time are some of the most common.
Soil type. Soils can affect tree health as much as or more than any other of the other current contributing factors. Compare current soil test results with those from tests taken at the same time in previous years to see whether any levels have risen or fallen. A key difference with woody plants is that when a soil test indicates a need for a specific nutrient, the woody plant usually takes much longer to respond than turf does. The general suggestion is to wait up to a year to determine whether a particular treatment had a positive result.
5. Evaluate known specifics
Each tree species has known maladies associated with it, but a frequent mistake made while trying to determine the cause of a decline or of the odd appearance of a tree is being overly mindful of the common problems of a tree species. This is a kind of “skip to the end” technique — an attempt to pinpoint the issue by taking the easy way out — and it leads to a greater potential for misdiagnosis.
Considering known specifics is a good step, but it should be done as one of the last steps, not the first. If you leave the considerations of planting, foliar/root disease, foliar/trunk insects, initial care, mulch placement and depth, site history, root disorders, soil type, weather and present conditions out of the process, you’ve done the tree a disservice.
6. Consider professional assistance
Triage can be a difficult procedure, one that may occasionally require outside assistance. If you’re still scratching your head after identifying the tree and working through classic symptoms, history, the here and now, and known specifics, it’s wise to call in a professional who performs triage on a regular basis.
Who’s the expert for triage? In most cases, an experienced arborist certified by the International Society of Arboriculture (ISA) is a good choice. As with any group of professionals, some are better than others, but contacting an ISA-certified arborist is a smart place to start. If the concern is tree stability, seek out an ISA arborist who holds a specialized certification called “TRAQ” (Tree Risk Assessment Qualification).
Beyond your control?
In the emergency room, some patients arrive is such rough shape that the doctors and nurses simply can’t do anything to save them. Similarly, in triage, some influences, historical events, old pruning cuts, soil types, previous planting procedures, disease-susceptible cultivars, invasive pests and weather events are just too great in their impact on the tree in question. Though this is frustrating and possibly unjustly incriminating (“What? You can’t do anything to improve that tree that was buried with 4 feet of soil seven years before you took this job?”), sometimes a superintendent or golf landscape manager just has to accept it.
On the plus side, there are an equal number of issues that can be controlled and management practices that can be implemented. At the top of the list of these are tree placement, routine inspection, proper planting techniques, amount of water applied, avoidance of compaction, nutrients applied, chemical and mechanical injuries, and the separation of turf and ornamentals.
John C. Fech is a horticulturist and ISA-certified arborist with the University of Nebraska-Lincoln Extension.