The old adage of “an ounce of prevention is worth a pound of cure” is as true today as it was when first uttered by Benjamin Franklin. Although Franklin was referring to human health, the same could be said of tree health.
Though the steps of prevention are implemented by developing everyday habits of thinking before acting and being a thorough tree care provider, it’s about what should be avoided as well as what should be done.
Can’t replace it… can’t fix it
Fixing or repairing is different for various parts of the green industry. Unlike the turf management world, where you can rip it out and reseed, scrape it off and resod or dig it all up and start over, trees are a long-term entity in the — elements that can’t be replaced quickly, or even in a growing season. As such, the timeframe for each entity is not the same — turf projects tend to be quick to establish and short-term, while trees take a long time to grow, yet contribute to the greenspace for a lifetime.
As a result of these differences, replacing and fixing is quite difficult, and in some cases, just not possible. Getting the size, shape and overall value of a 45-year-old red oak back after a loss takes time; in this case, 45 years. Oh, sure, a decent-sized specimen can be spaded into a nearby location, but not without extreme expense and risk of transplant shock. More moderate efforts, such as transplanting 44- to 88-inch root balls, often are successful, but it usually takes five to 10 years for the tree to adjust and begin vigorous root growth again, and remains a 12-foot-tall replacement in the place of that great old specimen.
Overall, the take-home message is that prevention is much more preferable than a short-term fix when it comes to trees in a landscape.
General prevention actions
Many prevention steps are specific to particular tree species or injury; however, at least two are overarching actions, ones that affect a multitude of potential maladies.
First, soil improvement on a large scale before planting will increase the capacity for lateral expansion of roots, add tilth to the soil profile and improve drainage in future planting sites. What’s “large scale”? In this sense, it means incorporating amendments based on soil test results to an entire landscape, office park or campus grounds.
Second, during landscape design and installation, separating turf from ornamentals will increase the chances of fertilizer and water being applied to meet the needs of each plant group. In most cases, turf has greater needs for these inputs than trees; if located together, trees are likely to receive more than what they need, leading to root rot, overstimulation of shoot growth and increased attractiveness to insects.
Third, the tree must be properly planted. Entire articles have been written on this subject in this and other publications, which underscores its importance. Depth of root ball, unwrapping circling roots, thorough soaking of the root mass, frequency of watering, mulching over roots but not on the trunk, using wood chips for mulch instead of rock, elimination of competing grass plants and other weeds and proper placement in the landscape are very impactful in preventing future problems.
Typical tree injuries
Some of the more common tree injuries and descriptions of damage are listed below. Each has a range or degree of damage associated with it, both in terms of overall influence on the tree as well as the malady itself.
Sunscald: Usually found on the south, west and southwest side of thin-barked trees, sunscald occurs in winter when the rays of the sun warm the bark to above freezing. Then, when the temperature drops after sunset, the warmed tissues experience cold damage. Sunscald results when this happens repeatedly over time. These effects can be minimized by installing light-colored winter sunlight protection devices.
Mower blight: Lawn mowers and other turf maintenance equipment sometimes veer from the grass and hit or scrape the bark and sapwood of trees in their path. The wounds resulting from minor occurrences usually close, with the processes of CODIT (compartmentalization of decay in trees) taking over. Install mulch to prevent mower blight and provide many other benefits.
Auto accidents: Similar to mower blight, except that the force of the impact is usually much greater. In many cases, in addition to the tissue damage, auto accidents often result in the deposition of radiator fluid and motor oil, which causes a burning and dieback of the root system. Plant trees away from sidewalks, driveways and streets to reduce the chances of auto accidents.
Soil compaction: Repeated passes of heavy machinery over the upper layers of soil press the particles together, eliminating air spaces and the potential for adequate water movement. During construction projects, restrict cars, trucks and construction equipment near tree roots. Over time, even lightweight equipment can compact soils.
Digging, trenching, construction damage: During these operations, roots are cut and torn, which limits their capacity to absorb water and nutrients and provide structural stability for the tree. Strategize with utility companies for options other than digging and trenching.
Root malformation: Often due to root rot from overwatering and desiccation from underwatering, new trees are the most common victim of malformed roots. As new roots become established, they are at a vulnerable stage in development. Water trees according to their need, not the turf’s need; check soil frequently for moisture content; use drip irrigation to deliver water slowly and gradually, and stop when the root zone is moist, rather than soggy or dry.
Co-dominant leaders: Shoots that are of equal size in the terminal section of the tree leader are subject to breakage as well as one compressing another as they expand in girth. Prune out co-doms early in a tree’s life to eliminate the weaker of the two and greatly improve its chances of success.
Stem-girdling roots: Roots that wrap around the bole instead of radiating horizontally are as troublesome as co-dominant leaders, yet often go undetected because of they are beneath the soil surface. Spread out roots during planting to reduce the number and influence of stem-girdling roots.
Herbicide injury: Misapplication of products designed to control turf weeds can result in drift to desirable ornamentals, including shade trees. Inform customers to read herbicide labels before they attempt to control lawn weeds. Temperature, wind speed and product type are key factors.
Rodent damage: Squirrels, rabbits and voles are common eaters of bark on young trees, which causes damage similar to mower blight. Install PVC barriers around young trees to reduce rodent damage.
Inadequate root expansion: Hardpan soils often limit the expansion of roots to support the shoot growth of a tree, particularly if the roots weren’t spread out laterally at planting time. In addition to making large-scale soil improvements, insist on 1,000 square feet of space (more for large species, less for ornamentals) for each tree to allow adequate root system development.
Storm damage, limb breakage: All trees are subject to limb breakage during storms with strong winds, yet some species are more prone than others. Choose wisely when planning and, when feasible, remove prone species and replant with a more durable species to greatly improve the sturdiness of the overall landscape.
Through implementation of these general and specific prevention techniques, tree injury can be limited. As a tree care provider, it’s your responsibility to use them whenever possible. Doing so requires attention to detail, as well as some scouting and monitoring operations, but in the end they are typical of the actions that separate the high-quality tree care givers from those that are just there to make a buck.