Bored to Death!

There are few trees that can rival white birch for its four season beauty in the landscape.

There are also few trees that can be so heartbreakingly disappointing when they suddenly fail. Growing up my parents had a large European white birch that gracefully dominated the front yard of our house. Every spring we would dutifully treat it to prevent bark borers.

One by one the birches in our neighborhood were removed after the slow process of dying back from the top down. Last year we took the birch down, not because of borers, it had gown so large that it no longer fit the landscape and was mechanically unstable.

The nemesis of most white birch trees is the bronze birch borer, Agrilus anxius, this North American beetle has caused extensive die offs of native birches in the past.

Most white barked birch trees are susceptible. European variety's are so prone to attack that they are not recommended for planting. In the wild birch trees prefer moist north facing slopes that allow them to have full sun on the crown of the tree and shade to keep the roots cool. This is a far cry from conditions most birches face in urban and suburban landscapes. Most birches in peoples yards are under stress. Stress makes birch trees attractive to bark beetle infestation.

The beetles lay their eggs on the rough patches of bark normally near the attachment point of branches. Eggs hatch and the larva tunnel into the cambium layer excavating zig zag tunnels around the tree cutting off the flow of sap as they destroy the trees vascular system.

Healthy trees may be able to wall the larva off by forming a callus layer around the insect and preventing it from excavating the tree tissue. More often the tree is stressed and slow to respond to the invasion and loses the battle. The callus tissue forms a lumpy mound over the larval tunnel that can be seen on the outside of the bark. The process from egg to adult can take a year or more and is dictated by the weather. Cold conditions slow the process down.

The result is active adult emergence and egg laying throughout the summer months starting in early June.

If you see the tops of your birch trees dying back you may have birch borers. Close examination of the dead branches will probably reveal raised tunnels under the bark can dark “D” shaped exit holes on the bark. Pruning out infested branches to below areas with any visible activity will be helpful. There are treatments available that can be applied to the bark or systemically to the root zone to limit the impact of the borers. Heavily infested trees should be removed from the area to prevent infestation of adjacent trees. Maintaining vigor and reducing stress factors present will be of great benefit. Properly mulching the area below the tree will help reduce root temperature and increase the vitality of existing plantings. Acting before you have any signs of borers will be of greater benefit than trying to catch up once they are present. The long term key to preventing birch decline is to chose resistant species and maintain the vigor of those that are susceptible. Contact your certified arborist for recommendations on birch trees to plant as well as maintenance regimes for your existing birches.

Lethal Weapons!

In the early seventies a man was going through a car wash in Houston Texas. He was watching spinning car wash brushes when an idea hit him, like a diamond right between the eyes. Why not use rapidly spinning plastic brushes to cut grass!

George Ballas is credited for inventing the string trimmer in 1971. Who knew that a tin can, some fishing line and an electric motor could produce such a useful and potentially deadly tool. From that point in time forward no tree has been safe from its ravages!

Trees are living organisms. There bark is designed to keep moisture in and keep insects and diseases out. Bark is no match for a string trimmer designed to cut tough fibrous grass. Trees and shrubs are susceptible to string trimmer injury year round but the most devastating damage occurs in late spring. Once trees leaf out the trunk start to grow in diameter. The vascular cambium, a slippery layer of plant cells just under the bark begins to divide and produce new living cells. Some cells differentiate in to phloem tissue immediately below the bark. Other cells differentiate into xylem closer to the hard woody tissue in the center of the tree. Xylem transports water and nutrients upwards in the tree and phloem brings carbohydrates back down the tree for storage and fuel to power plant processes. While this growing and differentiating is taking place the bark is “slippery” meaning it can release from the tree exposing the living wood of the tree. This is in stark contrast to later in the year when these cells have hardened and removing the bark is almost impossible.

You can test this on a twig or small branch, just dig your fingernail under the bark and see how easily the bark releases from the living wood underneath.

Impact from a trimmer string at the slippery stage can remove whole sections of bark.

The damaged area dies and the top part of the tree becomes disconnected from the bottom. If the damage completely circles or girdles the tree the tree will die. If the damage is less extensive the tree will struggle and eventually die.

While I don't advocate returning to the dark ages and cutting each blade with hand snips, I do have a few tips that can eliminate the damage caused by string trimmers.

Remove grass and unwanted plants from the area directly around the tree. Correctly munching under trees can eliminate the need for string trimming close in. There are commercial guards available that will protect the base of the tree. I don't recommend using them unless they are the only solution as they may restrict the growth of the trees by binding the root flare. Porous 6 inch plastic drainage tile, cut into a 6 inch tube and sliced on one side will allow the tree to breath. If you have to use these guards make sure they are loose and remove them frequently to check for damage. I have had great success with this on boulevard trees where the city was maintaining the lawn.

If you have an idea to protect your trees from string trimmer damage check with your certified arborist, they are experts in tree preservation.

It's Raining Landscapers!

The title of this article brings humor to a subject that is truly not funny, and may even prove fatal.

Arborists are tree care professionals with years of practical experience and extensive education that makes them experts in their fields. Having credentials alone is not enough to allow you to practice legally in most jurisdictions. State and Provincial licences prevent the lay person from pruning or treating tree diseases in most locals.

Furthermore working with trees can be extremely dangerous. Workers compensation plans are aware of the risk involved and charge higher premiums to tree care companies as a result. As a comparison landscapers typically pay 6% to 10% of every dollar in wages to their compensation plans. Tree care professionals are required to pay 30% of every dollar in wages to be properly covered for workers compensation. Liability and damage insurance are also much higher for legitimate tree care companies. Knowing these risks professionals make sure they have in house safety programs for tree climbers and tree care workers.

The International Society of Arboriculture offers training for all levels of tree care workers from the person on the ground to the most experienced climber. Professional tree care companies use these programs to insure worker safety and maintain there ability to get affordable insurance.

When you consider that statistical research has proven that in an accidental fall situation 50% of all people falling from 6 feet will die, training and proper insurance are a necessity.

Aside from the noted safety issues Arborists are tree care professionals that have the most up to date information on tree care. This ensures that you are getting todays best practices and treatments for your home's valuable assets, your landscape trees.

I work with professional landscapers everyday. Many of them have great knowledge of plants and shrubs. The best ones know their limits and know when to call in tree care professionals to complement their work on the landscape. The experienced professionals know that when your working off the ground you need to be licensed and insured. Some have learned this the hard way after damaging property or injuring themselves or their workers.

You may think you are saving a few cents hiring uninsured unqualified companies or workers. When they injure themselves on your property and seek legal redress, you won't be hiring a lawyer from the temp agency.

I have included a collage of a news item and hand bill advertisements that one commonly sees. This guy was lucky. I didn't include a different news item of a landscaper that was taking down a large tree with unskilled help. The worker was pulling the tree over with a rope he had wrapped around his arm. The tree fell the wrong way violently pulling the worker into an adjacent tree, his baseball cap offered no protection as his head was slammed against the tree. He was pronounced dead on arrival at the local hospital. A high price was paid by this worker for his lack of experience.

For your tree care contact a tree care professional, an ISA certified arborist.

Winter Injury

photo MSU

For the avid plants person spring is the most thrilling and heartbreaking time of the year.

It is at this time that we get to see which of our old friends has made it through winters harsh blast.

While some trees and shrubs may look as though they are headed to the great hereafter, caution is always the rule at this time of year. More than one plant, having been given last rites, has literally come back from the roots on the compost heap! Take caution before writing a survivor off.

To understand how plants succumb to the ravages of winter we must have a basic understanding of plant physiology. Leaves are incredibly useful plant organs are notoriously fragile when it comes to freezing. Hardy trees and shrubs generally lose these most tender parts in preparation for winter. Those that don't lose their leaves have thick waxy cuticles, or skins, that prevent dessication. Dying out over winter has led to the demise of many a plant. You don't need a microscope to see how thick and durable a spruce or pine needle is, just hold it in you fingers and break it.

If you failed to water your evergreens last year they may be looking a little burnt out at this time.

Check to see if the buds are swelling and pinch the bark to see if its supple and alive. If you scrape back the bark with your finger nail you may see green, it may not be the end for this tree, wait a few weeks and see what happens.

Arborvitaes, junipers and other scale leafed evergreens may look scorched at this time of year, again wait a few weeks before you throw these babies out with the bath water. In most cases simple preparation in the fall could have prevented some if not all of these types of injuries.

Watering well until freeze up is a good strategy. Antidesicants, waxy sprays applied in the fall, are good for established plants that can have problems as well as fall planted evergreens that have yet to establish.

Late summer fertilization of evergreens is not recommended as it may delay the onset of dormancy and leave trees and shrubs susceptible to winter injury. Wait until trees are in the process of becoming dormant before fall fertilizing.

As for the trees and shrubs that are suffering from the effects of last winter? They should be watered well and monitored for signs of improvement. A small amount of fertilizer or better still an organic soil enhancer like pulverized liquid sea kelp can help with root growth and speed recovery.

Don't over water trees that have been winter injured but don't let them dry out completely either.

Use your finger to see if the soil in the root zone is dry. Be patient you may save an old friend from the compost heap.

For Strong Winds

While it's true that “things will change, come what may”, it is a good idea to think about what you can do to prevent wind damage in the first place.

Knowing the resistance to wind damage of the trees your planting is a great place to start.

The following list of trees arranged from the least wind damage resistant trees to the most resistant.

LEAST RESISTANT

PINE / SPRUCE

CEDAR / JUNIPER

CHERRY / WILLOW

SILVER MAPLE

POPLAR

LINDEN

ASH

OAK

MOST RESISTANT

This list should be used as a guideline and if you decide to plant trees that are more prone to wind damage you can take steps to reduce the chance of damage.

When planting spruce plant in groups, single trees are more likely to wind throw. Spruce and pine trees need to be periodically thinned and dead wooded to open up their crowns and allow for air movement.

Trees like cherry and silver maple have hard brittle wood. Care should be taken to grow trees with good form free from co-dominate stems. These trees can be trained to have stronger structure and thinned to reduce crown density.

All trees benefit from having well drained sites. This should be arranged before planting.

Changes in drainage on your property or adjacent properties can have negative effects on your trees root systems.

Changes to grade or any injury to the roots of a tree will increase the chances of failure during strong winds. Construction on existing properties must take into consideration the effects on the root systems of mature trees. It take surprisingly little traffic to injure the roots of large trees.

Mature trees should be inspected for dangerous rot and large dead branches on a seasonal basis. Large dead branches should be removed promptly to prevent unexpected failure. Keeping the trees crown clean allows you to spot new dead branches and monitor the tree for signs of decline. Take the time to look at your trees before the wind sets you landscape back years! If your not sure what to look for contact your certified arborist.

Who Has Seen The Wind?

The title of this article pays homage to W.O. Mitchell's tale of life on the prairies during the dust bowl years. I don't think that there could be a more fitting title for a frank discussion of the visible effects of strong winds. We really don't see the wind, what we do see daily is its dramatic effects on the trees in our landscapes.

Trees are long lived stationary organisms that deal with wind on a day to day basis.

The events that lead to dramatic and some times tragic failures of trees, branches or entire forests often depend on changes to the the trees normal environment.

Take for instance wind, both its direction and strength. For any given location winds will come from a prevailing direction. Trees grow roots and crowns in patterns that compensate for this type of wind. A wind coming from any direction other than the prevailing direction, will cause more damage. Winds also blow at predictable strengths for most locations. Unusually strong winds from any direction will cause extensive damage to trees.

People have been watching the effects of wind long before hi-tech devices to measure wind speeds were available. Knowing common indicators of wind speed can give you some insight into tree damage and failure. One system of measuring wind speed related to its action on sailing ships was developed by Sir Francis Beaufort, a British admiral. The scale was updated over the years to include wind indicators for those of us on land. Beaufort's scale indicates that little tree damage occurs below 22 mph ( 35 km/h). At 27 mph, ( 44 km/h) umbrella use becomes impossible and large branches begin to sway. As wind increases up to 42 mph ( 68 km/h ) twigs begin to break off of the larger branches. Damage continues to increase and when you reach 60 mph ( 96 km/h) whole trees begin to topple over. Beyond this point damage increases dramatically.

What Beaufort's scale fails to take into account are the site conditions of the trees. Trees that are in full leaf will fail at much lower wind speeds. My own personal observations indicate that at 42 mph ( 68 km/h) trees in full leaf in saturated soils will topple readily. Soils that are drenched with rain or melt water do not hold roots with the same strength as when they are dry. Trees that have lost their leaves and are in frozen soil can survive much stronger winds. Drought stressed trees lose fine roots that anchor the support roots of the tree. The result can be increased potential for wind throw.

The answer to the question “ Why did this tree fail?” can be complicated. The correct answer may include the following: Root loss due to drought. Unstable soil conditions due to rain or thawing. Wind blowing from an unusual direction. Wind blowing at unusually high speeds. Rot or decay in the root system. Decay in the trunk of the tree. Recent or past construction in the area. One has to take all the factors into consideration to determine when a tree will fail. The answer to the failure question may be quite simple. Once trees or limbs are dead they begin a slow countdown to the moment when they break off and succumb to gravity. This is often chaotic and unfortunately can be tragic. A properly trained arborist can identify potential hazards an hopefully avert unfortunate failures of trees and branches. When was the last time your trees had your trees inspected?

Three Cuts to Success

The difference between a professional branch removal and a poor pruning job is often a result of poor technique. Before we discuss how to make a professional pruning cut we should discuss when its appropriate to make your own cuts and when you should call in a professional.

I don't perform surgery on my dog, I will do first aid to dress a small wound or remove a sliver. I don't have the necessary veterinary expertise. You should keep this in mind when you work on your trees. Prune your tree with a specific goal in mind. A small branch removal can be performed by most home owners with the right knowledge. If you have to leave the ground, or are unsure of the results of your pruning call a certifed arborist. Any amount of pruning on a tree causes injury. With this in mind I will out line a technique to remove most small branches up to 2 inches in diameter.

When removing small branches back to another branch make sure the remaining branch is at least 1/3 the size of the large branch that was removed. This will ensure the remaining branch is of adequate size to take over the role of terminal bud. If you left a ¼ inch twig at the end of a 1 inch branch that you removed the 1 inch branch would sprout at the cut and the twig may just die off.

The three cut method is the standard for removing larger branches.

Make your first shallow cut on the bottom of the branch 3 inches from the swelling where the branch attaches .
This swelling, the branch bark collar and it separates the branch tissue from the main trunk tissue. Never cut into the branch collar

PHOTO: LOWES.COM

Make your second cut on the top of the branch a few hand widths away from your first cut . This second cut will follow right through the branch. You will note haw as you approach the bottom of the branch the wood tears away and rips the bark back to the first cut on the bottom of the branch. The first cut is to stop the bark from ripping all the way down the trunk of the tree. Hasty pruning will result in these ugly tears.

The third cut starts below and just outside the branch bark collar and cuts strait through to the top of the branch. Once the weight of the branch is removed the bark will not tear. You will have a nice clean cut and no left over stub.

Again if you are thinning a tree out make sure the branch you leave behind is at least 1/3 of the size of the branch removed to allow it to take over with our excess sprouting. A good rule of thumb is to never prune more than ¼ of the live branches at anytime to allow the shrub to recover from the injury. You can always come back next year and do a bit more.