The Good Scout

In our previous article we discussed the history of pest management on landscapes and how it has evolved over time into I.P.M. Integrated pest management is the combination of cultural controls, like pruning and fertilization, with tree pest and disease control when necessary. This may sound contradictory but it is not, not all pests are at levels that impact the tree and not all diseases significantly impact the health of the plant or its utility in the landscape. Knowing the level of insect and disease pressure on a plant is complicated but always starts with identification. Both the plant and the problem must be correctly identified before the extent of the problem and the necessity of treatment are determined.

The key to identification is having a good scout, you must walk the property identify the trees and shrubs present and know the likely insects and diseases that may impact the landscape. Knowing each and every plant and disease is not possible as insects, diseases and the palate of plants in the landscape are infinitely variable.  Well, we as tree people and gardeners would like to think so, but sadly the variability is somewhat limited.

The scouted landscape patrol puts a qualified technician on your property armed with the tools of his trade, a keen knowledge of plants and there problems, and a variety of solutions to any issues he may encounter. Once the property has been scouted and the pest and disease problems have been recorded on a form or journal, the specialist goes to work correcting them. This may take the form of a spray or root zone injection or it could be a simple as cutting a nest of ugly caterpillars from your cherry tree and correctly disposing of them. Additional cultural treatments could include the removal of a circled root that threatens to strangle your maple or a suggestion that you relocate a sun loving lilac to a spot that is more open. Given the history of the property, kept in the treatment journal or in a file where the scouting reports are saved, the specialist may perform proactive preventative treatments. This may prevent issues that will occur several seasons in the future. For example, spider mites may be controlled in the spring when their population is low and before they cause premature defoliation of your burning bush in the fall. A simple application of horticultural oil at the right time on the right plant can prevent failures in the landscape in the future. By correctly limiting the amount and timing of applications you limit the number of applications that are necessary to catch up later. Reducing the extent and number of applications in your landscape is not only environmentally sound it’s economically sensible.

 Your I.S.A. Certified Arborist is up to date on the latest research and can plan and execute your scouted plant health care program with modern scientific techniques.

Towards The Good Scout

As long as there have been trees and shrubs there have been insects and diseases that live on and in them that reduce their beauty and utility in our landscapes and gardens.

A former professor and colleague, still very much active in arboriculture, would repeatedly regale us with tales of the good old days when you could just spray everything with lead arsenate and DDT. (He did this with a great deal of humor) This pretty well killed everything and life appeared to be good. However the toxicity, both instantaneous and residual was dramatic, indiscriminate and long lasting. Thankfully we have continued to evolve the process of maintaining our trees and shrubs with less and less toxic treatments while relearning cultural methods that require no chemical inputs. Indiscriminate spraying can result in the destruction of beneficial predatory insects, pollinators leading to resistant super pests that are difficult to control.

The discovery of chemical insect and disease controls was heralded as a dramatic breakthrough in both agriculture and horticulture. And it was, however old, time consuming practices such as breeding plant resistance and using cultural methods to limit the damage of pests were largely abandoned and forgotten when this new wave of chemical methods were embraced. Amazingly this “New Wave Approach “occurred in the 80’s, the 1880’s! It didn’t take long for problems linked to residual toxicity, and residue to spill over markets and dinner tables of the country and the world. In 1891 the New York Board of Health seized shipments of grapes and threw them into the river because they had visible traces of “Bordeaux Mixture “a mixture of copper sulfate and lime. Good for the grape eaters, not so good for the Hudson river. A British Royal Commission recommended safe levels of arsenate in food crops in 1903 after a series of poisonings. The British also threatened a ban on imports of American apples in 1925 due to high levels of lead arsenate. The industry continued to develop and expand the use of chemicals.

The realization that we may be harming ourselves and the environments continued to simmer until April Carson’s landmark book “Silent Spring” was published in 1962. This landmark book leads to the development of the modern environmental movement the initial steps towards finding a safer more environmentally friendly approach were called Integrated Pest Management.

Integrated Pest Management seeks to combine cultural, physical, beneficial, and chemical controls into an integrated approach to insect and disease control. Moving beyond I.P.M. the scouted Plant Health Care program puts a trained specialist on site to carefully monitor the trees and shrubs in your garden and orchestrate the correct treatment regime when necessary. The goal is always to minimize the application of chemicals, when possible using nontoxic products or cultural methods to limit the impacts of pests to acceptable levels. All treatments are carefully recorded and reported to the property owner as well as kept on file for future reference. I will continue to discuss the details of this topic in my next article. Your I.S.A. Certified Arborist is up to date on the latest research and can plan and execute your scouted plant health care program with modern scientific techniques.

The Flush Cut Question

In the beginning there were flush cuts and wound paint. And the world of arboriculture was perfect. That was until someone came along, Dr. Alex Shigo, and did the research that showed that both of these practices resulted in increased injury and decay in trees. Shigo turned the world of scientific tree care upside down with the concept of “Natural Target Pruning”

The basis of this concept is that trees have evolved a biological mechanism that allows them to deal with the loss of branches while reducing the impact to the remaining tree. Trees have been losing branches for a long time, 250 million years, in the case of conifers. Angiosperms, the flowering plants, a group that contains such notable trees as, oak, elm, and ash is a group that have a fossil record dating back at least 130 million years. And they are highly adapted and extremely successful in dealing with branch loss.

The tissues of trees are at first glance are all wood, however from a seemingly uniform group of tissues specialized structures are present both macroscopically and microscopically. When trees naturally shed a branch they do so at a point called the branch collar. This point can be quite prominent on many trees and is an enlarged ring at the base of a branch. Beyond the branch collar there are only branch tissues as it marks the separation from the trunk tissues. Also at the branch collar are a group of wound wood tissues that, once a branch has been shed, form a growing callus layer that acts to cover or grow over the wound left by the shed branch. These tissues seal over the broken branch tissue and prevent the further entry of decay organisms into the trunk of the tree. Trees seal damaged wood and don’t heal damaged wood. Painting wounds with toxic paints and tars sealed decay IN the tree and prevented the tree from growing over the wound site.

Shigo also developed a model to describe the process whereby the tree prevents decay organisms that have already entered the trunk tissue from spreading. The tree sets up a set of barriers in the area where the now dead branch tissues come in contact with the living trunk tissue. This concept is called, Compartmentalization Of Decay In Trees. The CODIT concept was developed using many years of field autopsies on trees that had had branches removed. Based on patterns of decay and staining, where the tree was able to wall off decay coming from removed branches, Shigo was able to identify 4 distinct decay barriers, preventing decay from moving up, down, in and sideways in living trunk tissue. This research shed a great amount of light on what we have always been observing in trees.

Considering the amount of time we have spent in the presence of trees it is a wonder that we have only in the last century started to scientifically examine our practices in managing our beautiful co-inhabitants. Your I.S.A. Certified Arborist is up to date on the latest research and can plan and execute your next pruning project with modern scientific techniques.

The Dual Nature of Trees

The concept that trees exist in two realms, one biological, and the second one the structural is not new. In nature it is not unusual to see a tree that is growing vigorously, yet is in danger of crashing to the ground because its structural stability has been compromised. Conversely you can see trees that are on their last legs biologically, but they are structurally solid.

Trees are long lived organisms that are completely immobile in their environment. As the environment changes trees adapt, grow, decline and eventually die. This can take place over a matter of years or centuries. We, as stewards of the trees environment, can do a lot to help balance the equation and extend the life of these immobile giants.

Construction and grade changes play a major factor in the decline of many trees. If you are contemplating construction, from a simple fence, to the largest additions, contact your Arborist to discuss the building plans before you break ground. A preservation plan is always simpler and more effective than a recovery plan. Root damage is the most common effect of construction and is difficult and time consuming to correct. While you are working improve the root condition of a construction damaged tree, you must also consider insects, diseases. These secondary pathogens will be drawn to stressed trees. The presence of human activity always has a stressful impact on tree growth and survival.

Trees grown in forests have very different growth conditions, light, soil moisture, nutrient availability, than trees grown in open areas like yards and city parks. Trees have evolved to take advantage of the benefits of increased light and many will grow wide broad crowns that may lead to instability. Instability can lead to wind throw or sudden branch drop. If you examine trees after a major ice or wind storm these over extended branches may be the ones most damaged

Pruning, crown reduction, and thinning can carefully reduce the size of a tree. Careful pruning will extend the life of a tree in open areas and greatly reduced spaces. Tree pruning is an art that is backed up by science. Knowing when to prune and how much is a skill that experienced arborists train for years to develop. Knowing when and what not to prune is also vital to the outcome of any pruning project. Proper pruning can extend the lives of trees and help the balance between biology and structural stability. I.S.A Certified Arborists are constantly updated on the latest pruning methods backed up by scientific research on tree wound response. I.S.A. Certified arborists have up to date information on tree preservation. Contact your I.S.A. Certified Arborist to plan and execute your next pruning project.

The Joy of Wood Anatomy

One of the most enjoyable chores is splitting wood. This article could just have well been called things you see while splitting wood.I know many people find this tedious and it can be dangerous. However if you know what you’re looking it can be a fascinating as any forensic drama on television.

Trees do not heal like animals, cells in wood, generally, do not recover when injured.

When compromised, the thick walled cells in wood are closed off from there adjoining cells by rot resistant chemicals like phenols and turpentines. Much the same way watertight doors are closed in a sinking submarine. These are the same chemicals that have been extracted for hundreds of years to produce wood preservatives and are the basis of many paints.

While these have largely been synthesized in modern labs, trees still produce these protective phytochemicals each time they are injured. It still surprises many people that trees are living dynamic beings, even if they are completely immobile in their environment.

Trees and woody shrubs contain or compartmentalize damaged plant tissue behind these strong chemical barriers and continue to grow over the injury. This process of compartmentalization prevents disease from entering the healthy tissue and overwhelming the plant and causing its death. A true case of life over limb, to save its life a tree will lose a damaged limb.

Back to the task at hand, while splitting wood you can find old pruning wounds and injuries that have grown over, encapsulated in new living wood. These barriers are not only resistant to pathogens they can be resistant to splitting as well! With modern hydraulic wood splitters you can power through these tough barriers and see the story contained within. I was splitting a piece of oak that had been removed for construction. The tree was at least sixty years old and very healthy when it was taken down. As I worked through the tree piece by piece I was amazed by the wood’s structure, beautiful rays and grains. As I split one large round I noticed an old branch stub that had been properly pruned many years ago and was now completely grown over. The areas of compartmentalization were clearly defined in all directions from the wound. Above, below and around, you could see the dark staining that prevented rot from entering the trunk of the tree. Whoever made the cut had done so properly and did not injure the branch bark ridge, a key anatomical structure in trees, speeding growth over the wound and preventing the expansion of decay. The most interesting part was that from the outside there was no hint, not a bump or blemish, of the drama, contained within. In fact if you look at the other side of the same piece of fire wood there is not a clue that the limb was removed and the tree had successfully grown over the injury. Any pruning no matter how minor or major is an injury to the tree. Successful limb removal involves knowledge of the art of pruning and the science of plant anatomy. I.S.A Certified Arborists are constantly updated on the latest pruning methods backed up by scientific research on tree wound response. Keep a keen eye on your firewood for these untold arbor-dramas and contact your I.S.A. Certified Arborist to plan and execute your next pruning project.