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.

Send Them Packing!

photo:USDA

Mega deals at the mega mart lead to increases in invasive forest pests. Improvements in transportation mean that a forest pest that laid eggs in packing crates on one continent can have its offspring delivered to the other side of the world just a few short weeks later. Add one more to the list of infamy that includes the Asian long horn beetle and the emerald ash borer.

The Sirex wood wasp is the latest unwelcome guest that has hitchhiked its ways to our shores in the cargo hold of high speed container ships.

Sirex noctilo F. is a native of Europe, Asia and Africa where it is considered to be a minor pest of stressed Scots pine. When it was accidentally introduced to pine plantations in South America it was no longer a bit player in the world of forestry.

In South American pine plantations mortality of up to 80% was recorded. Most of these plantations are planted with native north American trees such as Ponderosa, jack and lodgepole pine. White pine are less affected but are subject to attack.

In North America we have at least a dozen native wood wasps. Wood wasps are typically 1 to 2 inches in length, wasp like insects and generally are black and brown in color. The Sirex wasp has characteristics that distinguish it from the native species.

Sixex adults are generally blue to blue black with the males displaying an orange mid torso. The females have large reddish yellow feet which will be black on the rear legs of the males. The antennae on both the males and females are black.

If you thing you have spotted one please contact an expert for positive identification.

Native wood wasps attack dead and dying trees but Sirex wasps attack living trees.

The actual feeding of the larvae cause some of the damage, but a symbiotic fungus, Amylostereum areolatum that the female injects into the tree as she is laying eggs does the bulk of the damage.

The wasp completes its life cycle in one year. Adults emerge in mid to late summer and the females make an initial flight to a stressed tree. The females have been reported to travel up to 90 miles making quarantine efforts ineffective. Given that many trees are drought stressed at this time of year hosts will not be difficult to find. The female drills her ovapositors, a specialized egg laying appendage, into the bark of the tree and deposits up to 250 eggs and the symbiotic fungus under the bark of the tree. Fertilized eggs develop into female wasps, unfertilized develop into males. The larvae tunnel into the interior of the tree for up to a year. Pupae form close to the the surface before the adults emerge the following summer.

With the large number of two three and five needle pine in North American forests this pest is

expected to have a substantial impact.

Another hitchhiking newcomer, the emerald ash borer has just been located in Toronto, Canada as it continues to spread.

White Pine Weevil

From the Professor Tree Question Line

Hi,
My name is Silvia, I have planted Scot pines from PRFA for many years,
but the oldest ones 7 years old loose the top part of the tree.
The tree cracks at a certain height and the upper stem part falls.
In addition all the needles are yellow and the bark is not hard,
but like a film reddish that cracks peels.
The area also exudes sap, there is also a whitish substance.
The problem looks likeit starts from the trunk, and moves
outside toward the end of the branches.
The soil is very sandy and also very dry, and these past
two years have been very windy.
The trees were all in good shape at the beginning of the spring,
Are the  Scot pines trees could suffer from some disease.
Is there anything I can do? I appreciate any help and
advise you could give me.
Thank you so much.
Silvia C.
PS
I am very worried because it takes a lot for a tree to grow
here and now that these trees are big, they lose the top
part of trunk and branches. 

Sylvia,

Based on your description and the photos the problem is white pine weevil Pissodes strobi .

This native insect attacks Scots pine, white pine as well as white and Norway spruce. The damage is caused when the adults lay their eggs in the upper shoots of the effected tree. The larvae feed on the area under the bark known as the cambium. This feeding disrupts the flow of sap from the shoot and results in its death. The tree seldom dies from this damage and usually ends up with a misshaped top as a result. The damaged tops resemble a shepherd's crook this is a quick visual cue that the insect is present. Young trees are usually the target of this weevil. Removing the damaged crooks, by cutting them out a little below the damage, is an effective method of controlling these pests. The ideal time to do this is early to mid July around the time wild raspberries ripen. There are also chemical controls that are effective when combined with sanitation pruning.

Healthy Holidays

December 12, 2007,

At this time of year it is the custom to bring plants that are typically outdoors inside.
Natural trees have many advantages over their petroleum based imitators, you can add one more to the list .
Spruce, pine and fir are generally non toxic. Their taste and texture will usually stop a curious toddler or pet from eating more than a nibble. While there is little chance you would eat a spruce tree or make a salad from your fir, there are a couple of plants you should watch out for. Holly and mistletoe are two holiday favorites that should be kept out of reach.
Holly (Ilex opaca) with its glossy foliage and bright red leaves makes an excellent focal point on a wreath and adds a colorful accent to garlands. Unfortunately the berries are toxic to cats and dogs. Holly contains illicin, and triterpenoids, if your pet eats a small amount they may get sick, a large amount, and a trip to the vet will be in order. Keep in mind that a small pet needs only a small amount to become quite ill. The custom of kissing under the mistletoe, (Viscum album) dates back to the days of the Vikings and figured prominently in the death of the Norse God Baldur. This ancient plant has been bestowed with mystical properties. One not so magical property is its toxic potency . If pets eat mistletoe in any amount call your veterinarian immediately for advice on treatment.While I'm being a Grinch on holiday traditions, poinsettia sap can be a potent irritant to your pets mouth. Fortunately carefully washing the affected area is usually all that is needed to alleviate the discomfort.

Winterize Your Landscape !

Photo C. Ashcroft

November 30, 2007,

Many people take the time to prepare their vehicles for winter. Few people take simple steps to help their trees through the icy blast!

The first step in being prepared for winter storms is to take a quick inventory of your trees. Evergreens and large deciduous trees have different requirements when frigid weather arrives.

Evergreens should have been well watered right up to freezing. Cedars, arborvitaes and junipers may benefit from an application of anti desiccant. Trees have difficulty replenishing moisture in needles and leaves when the ground is frozen. Anti desiccants form a waxy coating reducing the likelihood that foliage will be dried out when winter weather turns suddenly warm and windy.

Some winter guests may become pests. Deer, rabbits and mice can make your

landscape into a veritable salad bar of winter survival foods. Repellents can be effective in reducing foliage browsing by deer, but mechanical barriers work best for mice and rabbits. Whether a little, or a lot, hardware cloth can keep most rodents on the run and looking elsewhere for a meal. Limit the amount of leaves and debris a the base of shrubs and trees. Debris will act as cover and encourage rodent activity.

Do your own storm damage assessment by walking around the large mature trees close to your house. With the leaves gone you can see branches and damage that may have been hidden in the summer. Look for branches that are at odd angles, generally most living branches grow upwards. Broken branches may be hanging dangerously, over paths and driveways.

Inspect cables that have been installed previously with binoculars to make sure they are not overgrown or frayed. If they were installed more than 5 years ago you should have them professionally inspected to make sure they are not rusted and are up to modern standards.

Are there any unusual cracks? Is bark falling away from the tree? Both of these signs could be indications of larger problems inside.

Visual clues are not the only ones to look out for.

I have had clients call in the dead of winter because their trees are making strange noises. Winter climactic extremes can open up cracks that become groaning creaking monsters when winter winds blow. A quick inspection from an I.S.A. Certified Arborist may put your mind at ease. It will also reduce the chance of a unexpected failures.

Trees and shrubs are a substantial investment, accounting for up to fifteen percent of your property value. A few steps to winterize your landscape can guard your investment and protect your home. Be wise – winterize, your landscape!

Timely Pruning

PHOTO R. UNDERWOOD

When is the right time to prune my tree? This must be one of the top ten questions when it comes to the topic of tree care.
When considering the timeliness of pruning one must consider various factors. The correct timing is not always as the old adage says “when the saw is sharp”.
The first factor to consider is that every pruning cut on a living branch is an injury. Pruning wounds cause the tree to use energy to contain the decay that is inevitably caused by injuring the tree. Prune only the minimum amount needed to achieve your desired goal. Pruning excessively will result in permanent injury to the tree and increased frequency of corrective pruning in the future .
The second factor to consider is the species of the tree. Various trees have different growth patterns that affect the time of year that you can successfully prune the tree.
Trees like maple, willow and birch should not be pruned in late winter or early spiring. This will cause them to lose copious amounts of sap that will slightly weaken the trees and will make a sticky mess in your landscape. Trees that tend to lose sap can be pruned when they have fully leafed out or later in summer.
The third factor to consider is the presence of insect pests and diseases. Some trees may be made more susceptible to these problems when you injure them by pruning. For this reason species like elm and oak should only be pruned when dormant. Typically after the leaves fall and into mid winter. In many jurisdictions there are prohibitions on pruning elms and oaks during the growing season. Generally most flowering trees can be pruned right after they flower to allow new flower buds to set. Pruning these trees too late can result in poor flowering response the following year. The art of pruning apple trees is based on elements of style and timing. The art of apple tree pruning would take several volumes to cover adequately.
With many deciduous trees the later you wait to prune them in the winter the greater amount of adventitious shoots you will develop the following year. These succulent shoots are less likely to develop if the trees are pruned in fall or late summer when the trees are still in leaf. This propensity to sprout new growth is the force behind rejuvenation pruning. This pruning technique is mainly practiced on leggy declining shrubs and is not recommended for most trees. Rejuvenation involves cutting the shrub off to within a few inches of the ground and allowing it to grow back from the resultant stump. This is commonly used in willow cultivation to get large numbers of canes to propagate vegetatively. Again this process is not recommended for mature healthy trees.
Spruce trees and most pine trees can be pruned in the spring when they are putting out new growth. Generally most evergreen conifers follow this rule and should not be pruned from mid summer until fall weather cools things off. Finally, it is important that your tools be sharp and up to the job at hand. Cuts larger than ¾ of an inch should be performed with a sharp saw, bypass pruners are the preferred tool below ¾ of an inch. These few general rules will be of help, but for more specific answers to tree pruning questions contact and I.S.A. Certified Arborist.