No Sweat !

“Do trees sweat”? The answer is yes, in their own way.

Trees use the evaporation of moisture to cool themselves when moisture is easily available.

Moisture in the leaves comes up from the roots through the trees vascular system.

This process is both passive in the form osmosis and active with cells moving the water along like a vegetative bucket brigade. This all works well in a particular set of limited circumstances. For instance, when ground water is available and the tree is in relatively

dry air. Only then can the tree release tremendous amounts of water. Some estimates run as high as 350 gallons per day with optimum conditions. 95% of this water is lost to the atmosphere in the process called evapotranspiration. Trees don’t exist to emit water vapor into the air and cool the globe in the process. However this seemingly altruistic process does occur as a result.

Transpiration uses water to move minerals from the root zone to the leaves where they are combined in the process of photosynthesis to create sugars. When trees release moisture into the atmosphere it does indeed cool the leaf. This is important because the process of photosynthesis in most trees occurs in a relatively narrow temperature range. This range is between 15’c and 25’ c or 59 ‘f and 77’f. Within this small range of temperatures the whole process works in an optimum fashion. Too low a temperature and the process is not efficient. At high temperature it begins to slow down as carbon dioxide becomes a limiting factor. Evapotranspiration works to keep the leaf in this optimum range.

Leaves are also able to dissipate heat directly into the atmosphere using a process called convection. If the leaf is hotter than the surrounding atmosphere heat will waft away from the leaf on air currents. Typically a leaf in sun light is slightly hotter than the surrounding atmosphere. This temperature gradient in itself allows moisture to evaporate from the leaf even if the relative humidity in the surrounding air is high. Trees are not immune to loosing more water than they can replenish from the roots. This causes a water deficit. If the tree is able to replenish its supply of moisture before the start of the next day it is able to continue growing even though this situation does limit the overall growth of the tree. This condition is called a daily water deficit. If the tree is not able to re-supply its water needs it will become desiccated and die.

Tree leaves regulate the loss of water vapor through small openings in the leaves called stomata.

These specially modified groups of cells are found on the outer surface of the leaf, top and bottom. As moisture exits the leaf it creates a humid boundary layer around the leaf. Wind moves the moisture away and allows the leaf to continue transpiring. If the wind speed becomes too great the leaf will close the stomata to reduce moisture loss also reducing the cooling effect losing moisture creates. For a more detailed explanation of tree water relations contact an I.S.A. Certified Arborist.

Dutch Elm Disease

Its time to get out in your neighborhood and look for threats to our oldest and most stately residents!

While neighborhood watches are nothing new, the threat you’re looking for is Dutch elm disease. Dutch elm disease arrived in North America in the late 1940's from Europe where it had devastated European elms. It is a fungal vascular disease that infects elm trees water conducting systems and the tree literally dies fighting to prevent the spread of the disease within.

The disease is spread from tree to tree in two ways: as fungal spores on the bodies of elm bark beetles and secondly by tree-to-tree connections called root grafts. The disease typically appears in late June and early July as wilting leaves in the upper crown of native American elms. The leaves turn brown and remain hanging on the tree. The disease progresses downward through the trees water conducting vessels. Eventually it spreads to the roots where it may be spread to adjacent trees through grafts. A young vigorous tree may die quickly within 2 to 3 months. Older trees may last for a season or two but will eventually succumb to the disease. Once the tree has the disease there is little that can be done to save it. Injecting systemic fungicides can stop the spread of the disease if you start the injections when only 10% to 15% of the crown is affected. Unfortunately by the time the disease is discovered it has progressed beyond this stage.

Well the tree is dying it is extremely attractive to female bark beetles who lay their eggs in brood galleries under the bark. When these beetles emerge they will carry spores on their bodies that will spread Dutch elm disease to healthy elms. Healthy elms with pruning wounds are attractive to beetles laying eggs. To reduce this risk the Province of Manitoba has an elm pruning ban in place from April 31st to July 31st every year. Spraying elms with a registered insecticide at the base of the trunk in the fall can reduce the number of over wintering elm bark beetles and slow the spread of the disease.
Watch your elms this time of year for dead or browning leaves. If you see some thing suspicious and are in a town that is part of the Provincial Dutch Elm Disease program contact your town office. The Provincial Dutch Elm disease survey Crew can be contacted at 1-204-726-6444. Contact an I.S.A. Certified Arborist for the complete story on Dutch elm disease and recommended measures to prolong the life of your graceful elms.

Be Prepared, (to prevent storm damage)

The title of this article is the motto of a well known organization, and it should be your mantra when it comes to preparing for summer storms.

The first step in being prepared for summer storms is to take an inventory of you trees. Walk all the way around large trees that are within 100 feet of your home. Do they have any unusual cracks, bark tears or mushrooms growing out of the trunk? Damage to the bark and branches could indicate internal decay that could lead to sudden failure.

Some species of trees form weak unions where branches meet the trunk. If a branch is weakly, attached high winds could tear it from the tree and cause damage to your property and leave the tree damaged and unstable. Installing support cables early can reduce the chance of a catastrophic failure. If your tree has had support cables installed in the past you should visually inspect them. 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.

Do the roots show any sign of disturbance? Cracks in the soil, heaving, lifting and tilting could be telltale signs of a tree that is starting to tip over. Soil erosion and drainage problems can leave many evergreens precariously rooted and subject to wind throw.

Trees along access roads, drives, garages and out buildings should be visually inspected before storm season and after major storms. Look out for hanging branches that may become lodged in the trees crown and not be readily apparent.

Electrical services telephone and cable wires should be cleared from branches and kept away from potential tree failure zones.

Treat all wires as if they were energized with lethal voltage. You never know what may have come in contact with the wires beyond your property. Always hire a professional who is qualified to work around electrical wires.

Mature trees close to buildings can act a a conduit for lightning strikes. The science of lightning protection can protect your home and save a prized tree. Large mature trees are a valuable asset to your landscape. The investment in a properly designed lightning protection system will pay off in the short run. Trees on large rocks or in open areas are particularly attractive to lightning.

LIGHTNING STRIKES

An Interesting Video,

http://www.youtube.com/watch?v=f6PJdAee7qY

Most Certified Arborists will perform a storm risk inspection as a part of your annual property inspection. They will be able to address your concerns and point out items you may have missed. Be prepared consult your ISA Certified Arborist.

For more information on this subject or any plant health care related questions, http://treecarecanada.ca

Green Ash

Trees of the Forest, Green Ash

June 25, 2007,

This tree has become one of the most popular trees for our streets and yards after onslaught of
Dutch elm disease. Green ash, also called red ash has one of the largest natural ranges in North America. It is found from Nova Scotia to Saskatchewan and as far south as the southern United States.

The leaves are pinately compound with five to seven toothed leaflets arranged oppositely along a central raceme. The leaflets are one to two inches long oval at the base and tapering to a point. The leaves are typically finely toothed above the middle of the leaf. The leaflets will fall off individually early in the fall and leave the slender hairy stalk on the tree through the winter. It has been said of green ash that it is last to leaf out and first to fall. Ash seeds are thin winged samaras that spiral down like propellers when they mature. Ash trees are dioecious, meaning there are both male and female plants. Female ash trees bear the seeds. Male ash plants will have flowers in the spring.

The Latin name of this tree, Fraxinus pennsylvanica refers to phraxix, Latin for to separate, and Pennsylvania the state where it was first identified in. I always assumed that its ability to split easily, as in firewood, was the source of the name, further research indicates it may refer to separating fields. Ashes were commonly planted in hedge rows to separate fields.

This tough hardy tree is still a favorite plant for shelterbelts. Ash trees have had a long history of human use. From baseball bats to furniture ash is a hard, strait grained wood.

When used as firewood green ash has high heat energy only slightly less energy than oak, fortunately it does not rot quickly if left uncovered.

This native tree is still highly recommended for planting and does grow quite quickly. Ash is susceptible to a defoliating fungus, anthracnose that attacks the leaf stems and leaves in the spring. If spring weather is cool and damp the trees may defoliate or have distorted foliage. Typically the tree will develop new leaves and it may not be a major problem. If the weather does not co-operate and the fungus persists over a number of years the tree may be weakened and develop unusual growth. Another problem pest with green ash is plant bug; this small insect punctures the tissue of the leaf and feeds leaving the leaf doted with small yellow dots. This may all change with the introduction of emerald ash borer.

Take the time to establish good branch structure if you are developing a tree for your yard. Keep in mind that in the wild, green ash is a river bottom tree and is tolerant of flooding. It prefers open sites but will grow in an existing canopy. It is moderately shade tolerant. Typically it will be found a bit higher in the riparian zone than Manitoba maple and below burr oak. Its neighbors may include willow, cottonwood, and where applicable American elm. For more information on native trees contact an ISA Certified Arborist.

EAB, The Real Deal!

EAB, The Real Deal!

Over the years there have been many real and imagined pests and diseases that have destroyed or threatened to destroy our forests. With this in mind I was somewhat jaded when the Emerald Ash Borer was put to the top of the list as the latest threat to our trees. Not again must have rolled off the tongues of every tree lover in North America.

After following the progression of this pest from infesting a few counties in the Detroit Michigan area to its current extent of five states and the Province of Ontario, something less civil should roll off the tongue! This pest may very well turn out to be the real deal, decimating all species of ash trees in areas that it becomes established in.

Emerald Ash Borer, Agrilus planipennis Fairmaire, is an exotic pest that was introduced accidentally into North America in the late 1990’s. The original infestation was probably the result of green wood in the form of packing materials that originated from the beetles home range in Eastern Asia. Whether it came from Russia, Korea, China or Japan is of little importance now. Logs infested with the larvae of the beetle were probably used to shore up shipping containers and were off loaded in Detroit. From there the adults, who can fly several miles when mature, found a welcome place to lay there eggs in North American ash trees.

It took several years before any one found the initial colonization and by then this prolific insect had developed a large population. The adults themselves feed on the leaves of ash trees but cause little damage. In late June to early July, they lay there eggs on the bark of ash trees usually in cracks crevices and fissures. The eggs hatch, burrow into the inner bark, the cambium layer and begin to chew their way though the vascular cambium layer in up to foot long serpentine feeding galleries. The larvae pupate and over winter under the bark of the trees and emerge as adults the following May or June. The beetles emerge from a small D shaped hole around 1/8^th of an inch in size.

The tree is unable to survive the injury to its vascular system, starts to wilt and die back and will last only one to three years once infested.

The initial area of North America has now expanded to over twenty thousand square miles and includes five states and the Province of Ontario. In the areas where the outbreak has been identified over 12 million trees have been removed in an effort to stop the spread of the Emerald Ash Borer. Official estimates in Ohio expect the prolific pest will cost 3 billion dollars in the next ten years.

Recently additional infested trees have been found further east in London, Ontario. Wood and wood products appear to be the primary means of transportation over long distances. Quarantines have been set up in infested areas.

Do not transport firewood from areas where the beetle is known to exist. As a measure of the severity of this threat, note that national agencies have begun an ash seed library to prevent ash tree extinction if quarantine measures are not successful.

Contact your local ISA certified arborist for up to date local information. Be on the look out for unusual die back in ash trees.

Fighting Defoliators One Worm at a Time

Fighting Defoliators One Worm at a Time

May 25, 2007

The new leaves are a welcome harbinger of spring. Green cankerworms eating the leaves are just as seasonal but not nearly as welcome. The process of controlling cankerworms starts in the spring and will result in decreased activity next year. You are not alone in your efforts. A number of parasitic insects feed on the eggs, larvae and pupas of these insects. Spiders, birds and small rodents also feast on the cankerworms at various times of the year. While all this eating is beneficial it does little to curb an epidemic population of worms. That is usually controlled by weather and soil conditions. Favorable weather conditions, like cold winters and late season frosts may control populations naturally. All of these factors combine to create a cyclical population boom and bust. Rather than waiting for the weather, or just talking about the weather, there are steps that you can take on your property to reduce the extent of the infestation next year. The first step is to arm your self with information on the life cycle of the two cankerworm species. The primary culprit that turns your elm, ash, or maple into a communal salad bar is the fall cankerworm, (Alsophila pometaria).

The life cycle of the fall cankerworm begins with the eggs over wintering in the upper branches of the host tree. The eggs hatch in late May as the new leaves unfold. Warm weather in spring will speed up the emergence of the leaves and the larvae. It takes approximately three weeks for them to mature and then the larvae spin a thread and drop to the ground like super heroes. When they reach the ground they spin a protective cocoon and change into pupae. Pupas are a stage in the development of insects where they change into moths. They emerge in September or October, as male and female moths. The males have wings and the females do not. At this point they have only to mate and lay eggs to start the process again. While the males are off being distracted by lights and flames, the females begin the long crawl to the top of the host tree to prepare to mate and lay eggs.

The spring cankerworm (Paleacrita vernata) has a similar life cycle with the larvae over wintering in the soil and pupating in spring. Both forms have wingless females. The female moth’s wingless crawl presents an opportunity to control both spring and fall forms of this insect. The application of sticky bands around the trunk of the tree will trap the females and prevent the deposition of eggs in the upper crown.

Start in mid summer, before the September long weekend, by lightly brushing off loose bark in a 6 inch band at 5 to six feet up the trunk of the tree. Do not girdle the tree by removing all the bark. You can then wrap glass wool, backed with stiff paper or foil in a four inch band around the tree. It can be secured with natural fiber like jute twine at the top and bottom of the strip. It is important to secure the band tightly to avoid the moths crawling under and not to tight as to injure the tree. Once you have the band in place paste sticky tangle foot, available from nurseries, evenly on the band. This will trap the females, so be sure to check it often to make sure there is no bridging over the trapped females. This would allow late arriving females to pass over the band. Reapply the tangle foot as necessary in the early spring to catch the spring cankerworm. Remove the bands in summer and reinstall in late summer. This will allow the tree to grow, and not damage the bark during the growing season. With single isolated trees this can significantly reduce the population of worms the following year. In a group, all trees will have to be banded.

When out breaks are severe, spraying with various products, as directed on the label, will give additional control. Btk, a bacterial insecticide works well when the insects are actively feeding.

Fruits of the Forest: High Bush Cranberry

May 13, 2007

You won’t likely find this cranberry next to your turkey this fall! That is unless you take the time to collect the berries yourself and make a delicious jelly with them.

The High Bush cranberry is some what underrated compared to other sweet berries of the woods.

High Bush cranberry, Viburnum trilobum, is a shrub with a large natural range. It is found in river valleys and open moist woods from the aspen parkland and the southern boreal forest. It is found in abundance along the Souris River, the Turtle River, and Assiniboine just to name a few areas. This shrub will attain a height of up to 12 feet in moist fertile soils, typically they are closer to 6 feet. This assumes that they haven’t been browsed by the local moose. The leaves are opposite, simple with three long pointed lobes typically 3 to four inches long. The Latin name, trilobum means “three lobed”.

The flowers are typical of most of the Viburnum family, flat topped white clusters of small flowers with larger sterile flowers, around the outer edge of the cluster. These sterile flowers may make the flower clusters more attractive to pollinators. You will see these flowers most often in June or early July.

The clusters of flowers once pollinated produce bunches of bright orange to red fruit.

These berry like drupes have a fleshy outer layer and a single large seed. The raw fruit is bitterly tannic and acidic. These are quite refreshing if you have a taste for them but should not be eaten in large quantities as they may cause cramps and vomiting. It is a favorite of bears and birds alike. Take care when gathering them in the wild not to startle the former. The Cree are reported to use the stems leaves and roots for a variety of medicinal propose. These range from pain relief to sore throat treatment. The bark is still boiled as a tea to relive menstrual cramps.

My personal favorite use for this fruit is in flavorful jellies. They have a unique odor, described by many as, sock like, but the taste is very good. I have included an untested recipe that seems to have the necessary amount of sugar. If anyone has good recipes feel free to email it to me.

This may be the plant to fill the gap in your diet as well as your wooded landscape.

For more information on native trees and shrubs contact an ISA Certified Arborist.

High Bush Cranberry Jelly

4 cups high bush cranberries

6 cups water

Additional water (as needed)

7 cups sugar

1/2 tsp. margarine or butter

1 pouch liquid pectin (Certo)

Bring the berries and water to a boil and simmer for 10 minutes. Crush the

berries or put through a food mill. Strain the juice in a cheesecloth-lined

sieve. Add any additional water if need to bring the juice up to 5 cups.

Bring the juice and sugar up to a boil. Add the margarine, then the liquid

pectin. Bring back to a boil, stirring constantly boil hard for 1 minute.

Remove from heat. Skim foam from surface and pour into sterile pint jars and

seal. Process in boiling water bath for 5 minutes.

Yield: 8 cups