When a tree or shrub doesn’t look the way it should, golf course superintendents become concerned. First, there’s the reaction of the client base – members, golfers and green committees. You wonder, “Now what do they think of me?”
Second, your pride is on the line. You want to produce and maintain a quality golfscape, one that exceeds expectations in terms of function and appearance.
Third, there is concern at a purely informational level. You ask yourself, “What did I do wrong?” or “What do these plants need that I don’t provide them?” and, simply, “What happened?” These are good questions to ask to set in motion the process of determining the cause.
For the inquisitive
You might have heard that certain scary movies are not for the faint of heart. But these sorts of epic motion pictures often have a certain pattern of predictability, and a devoted fan base that learns to predict the possible outcomes of each scene.
In a way, determining the cause of tree and shrub problems is similar to the way these fans digest a movie. An essential tool for the process is an inquisitive mind, one that is equipped and armed with knowledge of how woody plants function and possible maladies for each species.
Not all woody plant problems are subject to a cause-and-effect relationship, but most are. The confusing part of cause and effect is that sometimes the cause is acute, characterized by an external force imparted and subsequent quick reaction, while others are due to a slow and gradual response to a responsible source, a chronic cause. It’s very difficult to know at first glance which is producing the reaction, a short- or long-term cause.
A second confusing part of cause and effect is the speed of response compared with other plants in the golfscape. Generally, the woodier the plant the slower the speed of response. Compared with herbaceous plants such as perennial flowers and turfgrass, even an acute causal factor can take months for symptoms to be expressed. A good example is when a tree receives insufficient water. A rose or cranesbill generally would respond by wilting in two to three weeks, while an oak or pine might not express symptoms for two to three months, or more.
Causes are frequently influential – meaning, not just one cause. For example, a crabapple tree on a hillside might suffer less-than-adequate water infiltration, mower blight injury to the root plate, subsequent decay invasion and various fungal diseases. In this case, it could be tempting to spray a fungicide to prevent further apple scab infection, when the greater damage has been caused by the first three factors.
Is the cause a living organism?
Maladies of turf and ornamental plants often are subdivided into those caused by living organisms (biotic) and environmental and cultural factors (abiotic). So, as you stare at a sickly tree or shrub, the natural question is – which is it? If you search high and low, it’s almost always possible to find a lesion or two on a senescing leaf, but more often than not it’s wise to think abiotic first, then gravitate to biotic if no abiotic factors are evident.
A common human tendency is to think of insects and diseases as the cause of a particular problem, perhaps subconsciously because, well, there are insecticides and fungicides that can be applied in most cases.
So, if more than half the problems are not caused by living organisms, what are we talking about? In my experience, a cause or set of causes that are not living – such as drought, constricted roots and lack of nutrients – are responsible for about 60 to 65 percent of the problems woody plants encounter. Of course, this percentage is subject to change over time, and it certainly does not discount the importance and impact of biotic influences. These need to be fully considered and treated accordingly.
Take a step back
Instead of jumping to conclusions, a better approach is to take a step back and look for the obvious. Are trees supposed to have an electrical cord fused into the basal plate? Probably not.
How about asking the question: Is this a well-adapted species? After you are certain of the genus and species of the plant, take a gander at the hardiness zone recommended for its success. The best source of this information is your closest arboretum or botanic garden. A zone six plant will always struggle in zone five; it may grow reasonably well after planting, but then, due to colder winters than it likes, it will tend to die back and/or develop disease and insect problems.
Next, look the plant over, up and down for disruptions in the bark, trunk and stems. Disruptions could be caused by several factors including lightning damage, cankers or decay from old pruning wounds.
Mulch is usually a good thing, except when it is piled on the trunk. Remember, mulch is a root treatment, not a trunk/bark treatment.
Signs such as branches growing out of the soil or roots that are deep in the ground are symptoms of being planted too deeply.
Odd growths, such as bagworms or cedar apple rust galls, can always be an issue. Of course, it could be no problem at all, as in the case of shagbark hickory or sycamore, which Mother Nature designed to have exfoliating bark.
History of the site
Site history can be a valuable tool in the overall quest. Information about disturbances in the soil, topdressing activity and occurrences on adjacent properties is quite useful in determining the causes of maladies. These chronic influences are difficult to grasp; interviewing previous superintendents and longtime members can glean helpful information about affected trees and shrubs.
The flip side to historical influences is that which is currently taking place. What’s going on presently can be a multi-observational endeavor. Compaction, watering practices, herbicide injury, growth rate and weather patterns are factors that should be considered.
Next, think about what is taking place on the adjacent turf. For example, wherever practical, it’s highly recommended to separate turf from ornamentals in the golfscape. Because they share the same root zone, fertilizer applications made to turf will have a dramatic influence on the trees and shrubs.
If they required the same amount of nutrients, this would be just fine; however, most ornamentals require roughly a third to a half the fertility level of turf. In fact, unless the applicator takes steps to compensate, it’s common for woody plants to be overfertilized in a golfscape.
Finally, pay special attention to soil type and soil test results. It’s particularly useful to compare test results with those taken in the same month of years past to determine whether any nutrient, organic matter and CEC levels have changed.
COVER AND PHOTOS BY JOHN FECH