Here?s one obvious manner in which the plant and animal kingdoms differ: among plants, it?s the big guy that gets picked on. Ornamental trees ? towering so far above their ground-covering counterparts ? are just as susceptible to damage as things much smaller. In a lot of cases, they?re even more apt to be attacked by bugs, wind or weedeaters. Tall trees get the lightning; mature trees get the blights. When it comes to protecting these sensitive giants of the home and business landscape, the challenge involves keeping trees healthy and strong in spite of a long list of assailants.
What are perhaps the greatest tree opponents ? weather, insects and diseases ? are not easy to combat, and in some situations, these enemies are nearly impossible to conquer by even the most dedicated professionals. For instance, Robert Kinnucan, president of Kinnucan Tree Expert & Landscape Company in Lake Bluff, Illinois, reports that the county in which he is based has been placed in quarantine against the gypsy moth, and the Illinois Department of Agriculture has stated that populations of this defoliating pest are approaching uncontrollable levels. Dutch elm disease and the lerp psyllid are other examples of problems that have taken their toll on street and yard trees despite the efforts of science. Fortunately, within the bigger war, it?s possible for the landscape contractor to win a few battles.
Enmity with Mother Nature
First and foremost in factors affecting tree livelihood is environmental stress. Much of the nation has noted some pretty extreme weather patterns in recent years, from drought to record snowfalls, and landscape trees experience the full force of such climatic glitches.
When trees are faced with environmental stress, the goal, says Kinnucan, is to flatten out the stress curve as much as one can. He recommends contractors do this by mulching and watering in both summer and winter where conditions warrant it, to ensure a consistent moisture level. Most people realize the necessity of these actions during the growing season, but warmer-than-average snowless winters can be just as harrowing to a tree?s health.
In regards to trees in the landscape and the influence of the outside world upon them, Kinnucan notes that one of the most common myths he?s encountered is that these trees can thrive without human intervention, that ?Mother Nature? will take care of them. ?Going back to the environmental stress,? he laughs, ?that is Mother Nature.?
Sometimes, it may become necessary to give stressed trees an extra boost through the application of nutrients. A product called Super Thrive, developed by consulting nutritionist, biochemist and CEO of the Vitamin Institute, Dr. John A. Thomson, is a popular nutrient source for quickly reviving trees under duress from transplanting, climate extremes or other influences. Says Thomson, ?In reality, what is occurring is that we are providing compounds of carbon, hydrogen and oxygen the plants would otherwise have to wait to make.?
Contractors have reported seeing evidence of a tree?s revitalization immediately after the application of Super Thrive. The most common application of this product is via the soil, although it is also sometimes applied through microinjection or spraying.
For most arborists, insects and diseases come in at a close second to environmental influences as the most difficult-to-control tree threats. And while a good first, preventative step involves physical controls (proper site selection, removal of disease-carrying associated species, etc.), such a regime can do little to curb monsters such as Dutch elm disease, lerp psyllids or gypsy moths. The next phase, then, usually brings chemical protection into the picture.
Many tree care professionals may view micro-/macroinjection technologies as their preferred method of chemical treatment, but Richard Rathjens, senior agronomist with The Davey Tree Expert Company, has a different philosophy: injection as a last resort.
?We don?t do injections that often,? explains Rathjens, ?because if we can apply a pesticide to the foliage and control the pest or apply fertilizer to the soil and get the tree to respond, that?s the way we?ll go. We?d much rather treat the foliage or the soil than inject pesticide or fertilizer into the trunk.?
The reasoning behind such a stance is simply that injection requires drilling into the trunk, which is in and of itself a wound to the tree. Davey will use injections in situations where no other course is practical, such as in the treatment of iron chlorosis in oaks, caused by high pH soils. In these cases, Davey relies on the liquid injection of ferric ammonium citrate (and occasionally iron sulfate) into the affected tree?s xylem.
Dutch elm disease and oak wilt, says Rathjens, are other common situations in which Davey uses injection technology. For these two diseases, he says, trunk injection is the most effective method of treatment.
A situation in which microinjection has become a powerful cure is in the city of Newport Beach, California, which has seen heavy infestations of the lerp psyllid. According to John Conway, the city?s urban forester, ?Tree removal was not an option we desired, since many of these trees were old, large canopy trees which have been listed as Special Trees within our urban forest. We tried release of beneficial insects (ladybugs and lacewings) in hopes of controlling the lerp psyllid, with poor results.?
Conway explains how Newport Beach then discovered microinjection with Imicide from Mauget Company as a control option. The street with the worst infestation was chosen as an experimental site, and two dosages were applied. ?Within three weeks,? says Conway, ?the lerp psyllid began to disappear, the trees produced new leaf matter and the outcry for tree removal declined. Trees with an estimated value of $10,000 or more each were saved.?
In combating the Asian longhorned beetle in New York and Chicago, the U.S. Department of Agriculture has had success with the Mauget system of Imicide microinjection. Until now, this has been the only system used for preventative beetle treatments in these two urban areas, says David Cowan, a technician in the USDA?s Insecticides & Applied Technology Section.
However, this coming year, the program will also incorporate the use of Merit 75 WP soil injections.
The relatively low cost of equipment is what draws many contractors to the use of injection technology. However, Rathjens discourages his peers from letting affordability lead to indiscriminate use of this tool. ?I know some arborists are tempted,? he says, ?because of the low equipment investment, to use trunk injections when they should be trying to treat the tree in other ways.?
Kinnucan, on the other hand, is more accepting of wider usage of injection technology: ?It?s a standard therapeutic protocol with us.? Of course, he says, injections wouldn?t be used by his company to fend against relatively minor problems like leaf miners or aphids, but for more serious diseases, he feels the impact of the treatment procedure is justified.
Over the past 20 or so years, Kinnucan Tree Expert & Landscape Company has used iron metacaps, and they also used the Alamo microcapsule system for a while. Most of their microinjections today involve the Mauget system. Regarding macroinjections, the company started with Lignasan in the early 1980s, then became the first Chicago company to use Arbotect. Kinnucan then temporarily embraced the Alamo system before returning to Arbotect.
In the treatment of chlorosis, Kinnucan injects manganese and iron in conjunction with liquid root fertilization and reports good results.
No matter how a contractor approaches the use of tree injections, though, there are a couple of things to keep in mind to make sure the most favorable result is achieved. First and foremost, obviously, is that the manufacturer?s recommendations be followed to the letter.
When it comes to ensuring the effectiveness of micro-/macroinjection treatments, here again, environmental conditions can play a major role in a company?s success. ?One of the most important aspects of a successful injection program,? says Kinnucan, ?is making sure the plant
has adequate moisture.? This, he explains, is equally vital to fertilization and pest control injections.
Furthermore, he recommends that contractors avoid injections during dry/drought conditions, but if there?s no other alternative, one should water the tree prior to injection and then put it on a watering program afterwards. ?That?s probably, in my opinion, the most critical element to ensure a successful injection program.?
Public relations may also be a contributor to microinjection success. ?Explain the benefits and your overall goal before you appear with the product and start drilling holes into the tree,? Conway says. ?This can be done by a flier delivered to the public or client.?
Man against man
Another threat to landscape trees, but the one that?s perhaps the most easily defended against, is the threat created by homeowners, construction companies and ill-informed landscape maintenance employees. The solution can be as simple as training mowing and edging crews, or just making sure nothing comes into harmful contact with the tree.
?Provide barriers/boundaries to keep equipment and traffic off of tree roots,? recommends Jim McWilliams, vice president of Maxalea, Inc., in Baltimore, Maryland. ?These measures need to be in place before construction begins. Mulch at the drip line with wood chips to keep moisture into the roots. Install mycorrhizae ? mycorrhizae extract nutrients and water from the soil for their host plant and live off the plant?s sugars. Trees and plants with thriving ?mycorrhizal root? systems are better able to survive and thrive in stressful man-made environments.?
When it comes to designing and installing a client?s landscape, for the sake of the tree?s livelihood, those drip lines should be considered sacred ground. Says Kinnucan, ?What we?re seeing, unfortunately too often, is extensive landscaping placed within the drip line of existing shade trees and even newly planted shade trees.? This type of situation can lead to the tree?s decline, since perennial gardens intercept many of the nutrients at the soil?s surface that the tree depends upon, and the preparation of planting beds can damage the tree?s fibrous feeder roots.
Landscape contractors who have chosen to offer tree services to their clientele will do well to adopt an adage spoken by a famous Civil War general: ?Be there the firstest with the mostest.? In other words, detect problems early, and have as many potential solutions at hand as possible. To this end, Kinnucan recommends proactive property inspections at least four times each year to catch tree problems in their earliest stages.
Trees normally represent a significant investment by the client, an investment both in terms of money and time. After all, that tall and stately elm didn?t spring up overnight. Therefore, an ability to protect a landscape?s trees will be a tremendous service to the property owner, and, quite frankly, a service that the owner may expect, whether or not the contractor has billed himself as a ?tree expert.?