Treatment options to strengthen decay cavities or hollows are limited.  Past practices involved removing the decayed wood and filling the cavity with various rigid fillers. 

Currently, it is believed that filling cavities may do more harm then good.  In addition, the fill material may not strengthen and support the tree as much as the new growth that develops around the wound.  

If a tree has good vitality, it may maintain structural integrity by producing new wood around the injury. Removal of decayed wood from a cavity has little effect. However, if healthy wood tissues are damaged in the attempt to remove the decay, the tree’s ability to control the spread of decay may be reduced.  In most cases, it is better to leave the cavity alone.  If the cavity is large enough to compromise structural strength and there are targets present, the tree may need to be removed or pruned to reduce the size and weight supported by the weak area.

Production of new wood is important to tree stability, so ensuring favorable growing conditions for the tree is an important component of management.  Ensuring good soil health, moisture, and aeration, and applying organic mulch are examples of good management practices to which trees may respond favorably and improve in condition

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Treatment options to strengthen decay cavities or hollows are limited.  Past practices involved removing the decayed wood and filling the cavity with various rigid fillers. 

Currently, it is believed that filling cavities may do more harm then good.  In addition, the fill material may not strengthen and support the tree as much as the new growth that develops around the wound.  

If a tree has good vitality, it may maintain structural integrity by producing new wood around the injury.  Removal of decayed wood from a cavity has little effect.  However, if healthy wood tissues are damaged in the attempt to remove the decay, the tree’s ability to control the spread of decay may be reduced.  In most cases, it is better to leave the cavity alone.  If the cavity is large enough to compromise structural strength and there are targets present, the tree may need to be removed or pruned to reduce the size and weight supported by the weak area.

Production of new wood is important to tree stability, so ensuring favorable growing conditions for the tree is an important component of management.  Ensuring good soil health, moisture, and aeration, and applying organic mulch are examples of good management practices to which trees may respond favorably and improve in condition

Although arborists have tools available to measure how much sound and decayed wood is present in a tree, it is often less clear how much decay a tree can tolerate while still remaining a stable structure.  Decay in trees is common, but not all decay is a reason for action.  There are many variables that influence the stability of trees with decay. Some of these variables include tree and pathogen species; tree age and health; canopy architecture, height, and weight distribution; exposure to wind, snow, and ice; wood strength and toughness; root structure; and soil conditions.

The best thing for a homeowner or property owner to do is set up a tree hazard/tree risk assessment with an ISA certified arborist to give them a better idea of the tree’s structure.  However, any tree can fail given the right conditions.

When Appalachian Tree Service is called to look at a property, sometimes a tree will still have green leaves and the client assumes it is healthy. In realty, the tree has major structural weaknesses.

To keep a tree alive, often only a few thin layers of active xylem and phloem are needed; however, structural soundness requires a greater wood volume.  Green, full-crowned, and essentially healthy trees can still fail due to structural defects

This is definitely not a simple question and research can be conflicting.  In many parts of the world pruning is done throughout the year. When making a decision regarding the care of valuable trees on your property, make sure to always consult  a professional tree care company with an ISA certified arborist.

New research is starting to demonstrate that contrary to old methodology of pruning during tree dormancy, it may be better to do pruning on live branches in the late spring and early summer following a flush of growth after leaves harden and turn dark green. Research in Europe is suggesting that less stem decay occurs when pruning in the summer as compared to dormant season pruning.

However, during the initial flush of growth in the early spring trees have allocated a lot of energy to growth and may have depleted energy stores.  This is especially true for trees that are already stressed. Bark and Cambium are easily damaged and separated from wood when pruning takes place during a growth flush during this spring growth because early xylem is gelatinous and slippery.

*Avoid pruning at times of low energy reserves, when a tree is stressed, and when soil is uncharacteristically dry or flooded. (An Illustrated Guide To Pruning-Gilman)

It seems that pruning during this time allows trees to seal wounds from the drying effects of air better due to active defense substances that depend on cell growth.  Parasites have a hard time colonizing fresh-wounds when these defense compounds are active.  Woundwood and callus wood are also formed during this time further slowing decay. An exception to this rule might be in desert climates where trees have low moisture content in the summer.  This might also apply to late-summer or early-fall pruning where wood water content is low and disease causing fungal spore counts are high. This spore count remains high in warmer areas of the world even in the winter so the popularity of pruning during this time to reduce fungal infection may not be effective.  This principle applies at anytime of the year if the area is experienced severe drought conditions.

Heavy pruning in the late summer or early fall can initiate a late season flush of growth and delay dormancy.  This new growth has not been hardened off to the cold and can be damaged by early frost.  In addition the cambium layer around pruning cuts at this time of year is more susceptible to dieback and the pruning wounds are more prone to cracking.

When heavy pruning is done in the late winter just before the spring growth flush, the tree is defense systems are activating but the large associated energy expenditure has not happened making it a good time.

As far as growth control, non-pruned trees grow the fastest.  By removing live branches you are removing photosynthetic capability and energy reserves causing a dwarfing effect.  If your pruning objectives are mostly pertaining to growth control, pruning trees just before the spring growth flush will encourage growth while pruning after this growth flush will slow growth.

“Only healthy, vigorous, young, or medium-aged trees should be pruned using this strategy. Pruning live branches from unhealthy old trees, including those impacted by construction activities, at a time of low energy reserves, during or just after the growth flush, could deplete them further of much-need energy reserves and energy producing tissues” (An Illustrated Guide To Pruning-Gilman)

Light pruning (removing less then about 10% of the foliage on medium-aged trees or 20% of the foliage of young trees) can be done most of the year as long as the branches being cut are small diameter.

Pruning in the dormant season is recommended on certain trees susceptible to diseases and insects (such as borers) in certain areas of the country. During the dormant season there is an overall reduction of inoculum.  Avoiding pruning in wet conditions can lessen the change of fungal infection by reducing the vulnerability of freshly cut wood.  Pruning during times when insect vector numbers are not as active is advised but varies by climate.  For example, an insect vector may still be active in Georgia in November but in Wisconsin the insect vector and fungal pathogen is inactive.  If pruning a tree that is already infected by a disease such as fire blight, avoiding wet conditions and pruning during the dormant season can reduce the spread of disease to other plant parts and other plants.  In the growing season, pruning can open wounds that can start other infections.  Avoid wet and warm weather when pruning infected trees.  Pruning often by making small cuts is also a way to reduce the chances of infection.

Most fruiting trees are best pruned in the late winter just before bud break.  This reduces the chances of winter related damage. However, Pears, apricots, and peach trees among other trees that are susceptible to bacterial canker should be pruned in late fall to avoid infection through pruning cuts. 

For the desired multi-stemmed form on young ornamental trees, is is best if they are left un-pruned for 2-3 years to allow for rapid growth.  Pruning lower limbs directly after planting can slow growth.  If the tree is severely headed, the new shoots will be vigorous yet the overall growth of the tree will be slowed.  To avoid having to head these trees to induce a fullness of crown, wait the recommended 2-3 years before pruning.  After the third year, they can be pruned to their desired shape.

In conclusion, pruning recommendations have changed due to ongoing research, which includes conflicting research. This makes sense due to the fact that arborists deal with so many species of trees with different susceptibilities in different climates and environmental conditions. Arborists also work with trees of varying health and vitality.  An arborist must use his expertise, and understanding of these factors while trying to meet their client’s expectations.  This involves making the decision of whether or not the client’s needs can be met while maintaining a healthy tree. 

Because each cut has the potential to change the growth of a tree, no branch should be removed without first establishing clearly defined objectives.  Several pruning methods can be used to meet the desired objectives.

Removing the correct stems and branches to accomplish specific goals is as important as making correct pruning cuts.  If the wrong branches, or too many branches removed, even if proper pruning cuts are used, nothing of merit has been accomplished. 

Pruning goals must consider tree growth and development and the effects on the tree over the long term. 

Objectives include:

·      Reducing the potential for tree or branch failure

·      Providing clearance

·      Reducing shade and wind resistance

·      Maintaining health

·      Influencing flower or fruit production

·      Improving a review

·      Improving aesthetics

Heading cuts are used on the trunk and/or large-diameter branches of trees to reduce height or spread.  This substandard practice, called heading or topping, is not recommended because it damages trees permanently.  Heading large-diameter branches causes many problems, including massive decay in many species and many dead branch stubs (Gilman and Know, 2004)

Here are some major problems directly related to heading (topping) trees in the landscape:

·      Decay and cracks in the cut stubs

·      Depletion of energy reserves and a reduction in energy storage capacity

·      Destruction of tree architecture and structure

·      Vigorous sprouting with weak attachment

·      Unnatural and unappealing appearance to many people

·      In the long term, more cost than structural pruning or thinning

·      Possible damage to trunk and branches from sudden sun exposure

·      Inhibition of root growth

·      Increased susceptibility to boring insects, canker, and root diseases

·      Possible mortality

·      Susceptibility to future storm damage

·      Even though crown density is initial reduced, it is increases quickly after pruning

“If a tree needs regular pruning to keep it small, perhaps the wrong species was selected for the site” (An Illustrated guide to pruning third addiction, Edward F. Gilman)

Arboriculture ( /ˈɑrbərɨkʌltʃər/) is the cultivation, management, and study of individual trees, shrubs, vines, and other perennial woody plants. It is both a practice and a science.

The science of arboriculture studies how these plants grow and respond to cultural practices and to their environment. The practice of arboriculture includes cultural techniques such as selection, planting, training, fertilization, pest and pathogen control, pruning, shaping, and removal.

Risk management, legal issues, and aesthetic considerations have come to play prominent roles in the practice of arboriculture.

Arboriculture is primarily focused on individual woody plants and trees maintained for permanent landscape and amenity purposes, usually in gardens, parks or other populated settings, by arborists, for the enjoyment, protection, and benefit of human beings. It is therefore related to, but distinct from agriculture,horticulture, urban forestry, forestry, dendrology, and silviculture.

Today Appalachian Tree Service was called out to look at a cherry tree that seemed to not be doing well and the homeowner was very concerned that they might lose the tree. Jesse Milton from Onebark, LLC. was with me today to help in the diagnosis process.

The tree was a 14” Yoshino cherry and was severely stressed.  50% of the stems were dead (2 out of 4).   We identified ambrosia beetles in the trunk and possible evidence of Fire Blight. Infection was found (dead leaves, small splits in trunk around branch unions and lesion like bark splits along stems).  We made a small cut into an old pruning cut on a suspected dead stem and found that the cortex was not green.  There were brown leaves still attached to a few twigs and although it was tough to look for other symptoms of fire blight due to how dead the leaves were, we noted shepherd’s crook shape on the petioles.

Our recommendations:

1. Remove prune/remove the dead stems since the customer really wanted to keep the tree. 

2. Water both trees with soaker hoses and use a pie pan to measure water application to accomplish 1” of water per week.

3. Mulch around the tree using wood chips

4.  We will apply a trunk wash of Bifenthrin 23.1%, per label instructions, to both trees, once per year.  

Because the root system of a newly planted tree is limited, fertilization is not always recommended at the time of planting.  Excessive fertilizer salts in the root zone can be damaging and can lead to increased water stress. If fertilizer is used in the first growing season, application of a slow-release nitrogen fertilizer is suggested.  Nitrogen stimulates root growth and may be beneficial when applied in conjunction with proper watering practices.

Contact Appalachian Tree Service for an evaluation of your newly transplanted trees along with the other trees and plants in your landscape.

Trees cannot actively fight or move away from harm, but that does not leave them defenseless.  Trees have a number of features that serve as protection: thick bark, thorns, leaf hairs, thick cuticles, and any others.  In addition, certain cellular materials may resist decay or may be indigestible by insects.  Another defense mechanism is the production of chemicals that resist insect feeding, pathogen infection, or decay.

A developmental process unique to trees is the ability to compartmentalize, or “wall off,” decay.  Compartmentalization is the process by which trees limit the spread of discoloration and decay.  After a tree has been wounded, reactions are triggered that cause the tree to form boundaries around the wounded area.  (From the International Society of Arboriculture)

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