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Tree trouble
Careful analysis can help determine where
the real problems lie with trees on golf courses.
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Sure, the top issue facing most superintendents is the health of the greens and other playable areas on their golf courses. But not too far behind is the presence and potential impact of problematic trees. Some members and influential golfers think that more trees are needed. Others want anything woody removed as soon as possible.
So, what’s a superintendent to do? Wring your hands in angst? Nah. Start by giving those troublesome trees a good look-see.
Site analysis
The first step to working with any issue dealing with woody or herbaceous plants on the golf course is site analysis. Ask why. Why is the tree suffering? Which causal agents might be responsible? The only way to know is to perform a site analysis, a process that will identify the localized set of growing conditions, reasons for the original plant material choices and possible factors for its development into a problem tree.
Start by simply writing down a description of all apparent conditions nearby — soil types, drainage patterns, hours of sun received each day, wind patterns, utility location, nearby business operations, health of the turf nearby, etc. Then, document the symptoms of the tree such as wilted leaves, stunted growth, cracked bark and spots on leaves or stems.
This is just what the detectives on the TV show “Law and Order” do — they take down all the facts and then try to interpret them into a logical set of circumstances or developments that caused the death of the victim. Only in our application, the “victim” is a tree and our analysis is done to determine what led to that tree’s untimely demise.
After all these notes have been taken, piece them together to diagnose maladies and/or determine if the tree is meeting the original goals that were set out when the course landscape plan was created. A pin oak tree with yellow leaves with green veins would suggest that chlorosis may be a possible cause, while cupped leaves with sticky sap on the leaf surface may be a good indicator that spider mites or aphids are damaging the tree. More serious concerns of pine wilt, Dutch elm disease or emerald ash borer may spell doom.
At any rate, if tree removal is necessary, then you’ll have the pertinent documentation to help any objecting parties understand the need for removal.
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It will take some detective work and possibly soil samples sent to the lab to determine the cause of an ailing tree. Photos by John Fech |
Sentimental journey
Just as important as the presence of disease or possible improper placement is the here-and-now question of “who feels what about which tree?” After all, perception is reality. Is it a memorial tree, a signature tree, a state tree, a favorite tree of the green committee chair or was it planted by the head of the spouse auxiliary group? Or does anyone really remember when and why it was planted?
If possible, interview the designer or architect about their reasons for selecting that specific tree. It may be that there were sound reasons for the choice, and that subsequent events have changed the growing conditions such that it’s no longer a good fit for the location. Or it may be that it was simply a case of looking at a long list of possibilities and picking one at random for the installation.
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Before deciding to remove a tree, try to contact the course designer to ask the reasons for selecting that particular tree. |
Solving the problem
If you choose to keep the tree on the course, you’ll need a strategy for returning it to health. It’s pretty rare that using only one method or treatment will suffice, which is probably one of the reasons that it’s a “problem tree” now. Following are five factors that are worthy of consideration for many trees on the golf course.
Mulch placement
At first glance, placing mulch around trees sounds pretty simple, but there’s really a lot to it. First, use a wood byproduct mulching material, not rock or stone. In fact, using rock or stone is a good way to add stress to a tree, not take it away. There are lots of choices available, from wood chips, hardwood bark and stump grindings to pine needles. There are a few subtle differences among them, and most arborists have their preferences, but if it’s chopped or shredded woody material, it’s all good.
The best tree growth will occur when you’re able to duplicate natural conditions for trees, ones that would exist if they grew from seed on their own in a forest. Ideally, mulch will decompose over time, taking on a similar structure to that of a compost pile. In a forest, the material that litters the forest floor is called “duff.” The next time you have the opportunity to wander through one, reach down and grab a handful. You’ll find various combinations of ex-plant parts, including bark, fruits/seeds, leaves, petioles, stems and flowers.
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Problem trees, if left on the course, usually require a strategy to return them to health that involves a combination of methods and treatments. |
On top, they’re in a fairly recognizable form, but just a couple of inches down, they’ve likely started to turn into leaf mold, with pre-compost and actual compost a couple of inches beneath. In these layers, thousands of very beneficial organisms do the hard work of breaking down fallen plant parts and recycling nutrients back to the tree.
Try to replicate this arrangement, formally called sheet composting, for the trees on your golf course. Apply 3 to 4 inches of loose, coarse wood mulch under the trees. Start about 3 inches away from the trunk and extend it as far away as the function of the situation will allow. If mulch is piled against the trunk, the bark may stay wetter than is desired, leading to problems such as Armillaria root rot.
In addition to the nutrients, many other benefits arise from proper mulching. Several research studies have indicated that mulch keeps the soil cooler in summer, holds moisture near the roots and suppresses weed growth, which, along with turf, competes with tree roots for nutrients and water. Lowered bulk density and greater mycorrhizae populations also are typical outcomes of mulch applications. In many situations, soil compaction is further reduced in mulched areas, as they typically become less trafficked for golf play.
Organic matter and pH content
Nutrient, organic matter and pH levels that are less than optimal can lead to big problems for trees, just as they can for turf. The classic chlorosis scenario is most commonly caused by improper balances in pH, organic matter and nutrient levels.
Silver maple, pin oak, magnolia, sycamore and sweetgum are examples of tree species that commonly develop symptoms of yellow leaves with green veins due to a lack of micronutrient uptake. The soils in most areas of the U.S. contain adequate amounts of iron, and although some trees suffer due to a lack of iron, it’s a fairly unlikely causal agent. In most cases, the pH of the soil is either too low or too high, which limits the availability of the nutrient. Other causes include a small or damaged root system and various pest issues.
Adjusting pH to increase uptake can be difficult, but not insurmountable. Based on the results of a good soil test, make adjustments to increase or decrease the pH by adding lime or sulfur, respectively. Check with your soil test lab to obtain their preferred protocol on taking a soil sample for trees. In most cases, the sample should be collected at a 3- to 8-inch depth, about 1 cup of soil for each of a dozen subsamples.
Making improvements in this area should be looked at as a long-term project. Depending on the treatment method (entire magazine articles can be written on the pros and cons of various methods), it can take 12 to 24 months to observe an improvement in the appearance and density of the tree foliage. Follow-up sampling should be done every year to determine if progress has been made toward moving the nutrient and pH levels toward the desired level.
Restricted root zones
Obviously, all trees on a golf course are not located in areas with high-quality soils or adequate root expansion capacity. Restricted sites include parking lots, clubhouse plantings, golf car paths, turnarounds, refreshment stands, ponds, tees and out-of-bounds areas. In most situations, the smaller-than-necessary root mass leads to other problems, and a sort of Catch-22 develops.
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Use wood chips, hardwood bark, stump grindings or pine needles as tree mulch to replicate the material found on forest floors, which recycles nutrients back to the tree.. |
When roots are restricted, they often twist, curl and eventually girdle the tree instead of spreading out wide and lateral. Smaller than optimal root volume often leads to inadequate amounts of nutrients being absorbed. This causes less chlorophyll, carbohydrates and sugars to be made, and less to be transported to the root system, which is in desperate need of nourishment. Many other factors on these sites cause a reduction in the size of the root system. In addition to proper mulching to improve the remaining soil volume, two other approaches are worthy of consideration:
Soil replacement technique. When soil tests indicate a lower than optimal (less than 1 to 2 percent) organic matter content, consider replacing small portions of the soil surrounding the tree to create more favorable conditions for root growth. This technique can be implemented several ways, but all involve removing soil volume in the tree’s root zone, moving it off site, discarding about half of it, mixing the remaining soil with compost, mycorrhizae and leaf mold, and replacing it. These greatly modified soils allow for increased root growth.
Plant growth regulators. If it is impractical to replace or modify the soil, a treatment of a plant growth regulator such as paclabutrazol (Cambistat) can be beneficial. Similarly to the effects of turf growth regulators, increased root development and chlorophyll production can be achieved with application. Arborists sometimes call such a treatment a “kick start.”
Soil moisture content — too much?
All plants in the golfscape should be maintained with the optimal root-zone moisture content in mind. In general, most trees, shrubs and perennials require about half as much water as turfgrasses do. This is problematic because on many holes, trees and turf share the same root zone. Thus, if the entire surface area is irrigated with the same amount of water, the trees are receiving much more than optimal.
In well-drained soils, tree roots that receive extra water may not be damaged because the excess can freely move downward, allowing many of the soil voids to remain open and provide adequate oxygen to them. However, in heavy, poorly drained soils, this is not the case. These soggy conditions usually lead to poorly oxygenated soils and, eventually, to root rot. Once the roots rot and slough off, the tree loses much of its capacity to grow normally, which leads to very sick-looking plants.
Problems with incompatible soil moisture requirements can be dealt with by:
• Watering turf less near the tree.
• Converting nearby turf from higher-input species/cultivars to ones that perform best under low inputs. These tend to be better companions for trees. Specific information on choosing low-input cultivars is available from www.ntep.org.
Using antidesiccants
Evergreens can be a big asset to any landscape. In fact, most landscape designers tell me that no design is complete without specifying at least one, and more likely a grouping. In northern climes, where members and party goers frolic in the clubhouse and look out at a gray, drab winter landscape, masses of green are a welcome addition. Of course, all sorts of evergreens can be used, from foundation plantings to distance markers to backgrounds for greens.
The cold winds of winter can be rough on pines, hemlock, boxwood, holly, spruce, firs and the like. They remove essential moisture from tree needles, moisture that cannot be easily replaced by a frozen root system. When this occurs, the tree is left with a drab, lifeless color, one that is much lighter than the healthy hue. Severe cases leave the needles with no inner moisture at all, which kills the needles and starts a weakening of the tree, leading to susceptibility to other maladies. The use of an antidesiccant can dramatically reduce moisture loss.
These products are designed to coat the outer needle surfaces with a lightweight glue-like substance, which serves to keep precious internal water from leaving the needle. In general, they last about five to six weeks before the sun and wind render them ineffective. Applications should be made about six weeks apart to keep valuable trees protected. They are designed to be used on cool days, above freezing, so that the liquid will dry on the leaf surface before it freezes, allowing for a better residual.
One word of caution: Be sure to clean out your sprayer after making an antidesiccant application. After all, this is a glue-like substance, and will harden in the linings. A simple soap and water solution flush will prevent damage to your equipment.
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