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

Can you Build the Perfect Tree House?

April 22, 2007

Many a child has experienced the joy of gathering bits of cast off wood to create a lofty palace.

I remember many hours of hunting and gathering to make the perfect tree fort. In retrospect my lack of carpentry skills probably saved many a tree from an untimely death. Trees are long lived dynamic organisms that sway in the wind and grow over time expanding there girth and height. Houses are long standing static decaying structures that are built not to move and require constant input to keep them from falling apart. How can the two exist in a Tree- House?

Often times the answer is, not very well.

If the house is attached firmly to the trunk and wrapped around the branches completely two things will happen. First the house will start to break up like a ship on the rocks as the tree moves to and fro in the wind. Secondly the boards that are used to attach the tree to the house will slowly strangle the tree and eventually cause it to die off above the attachment point. Surprisingly one thing that won’t happen is the tree will not lift the house higher into the air as the tree grows. Trees don’t grow like Jacks bean stock. Trees grow incrementally adding layers of cells to the outside, like dipping a candle in wax or applying layers of paint. Trees gradually get thicker and larger. Only the growing tips of the branches will elongate and get taller or spread wider.

Now back to my lack of carpentry skills. Typically as a ten year olds we would gather

two by fours and old bent nails to attach a frame work in a few places to the tree. A piece of weathered plywood would be flopped on top of the makeshift floor joists. The whole thing was not very safe, not very sturdy, yet it was relatively harmless to the tree. A few strong winds and the whole thing would collapse or have to be reattached to the tree. These rarely survived the winter.

If you consider that half of the people that fall accidentally from 6 ft or higher do not survive the fall, it’s lucky my cohorts and I are alive. Some tree house makers may have grown up into crack liability lawyers.

Do all arborists wax poetic about there childhood tree adventures, or is it just me? The other day I was out to a property where a client had hired a professional carpenter to build a state of the art tree house in a multi stem willow. They had built it structurally to code.

Was there anything we could do to stop the tree from ripping the stoutly built structure apart? How long would the tree last with this house attached to it? The prognosis was not good; the tree had already started to swell over the 2 by 12’s that completely surrounded the stems of the tree and the roof was not in good condition either. With the tree house in place, the tree had 3 to 5 years before it started to die back and fall apart. The house was also supported by 4 by 4 poles that had either bent or lifted depending on how the house had shifted.

If you’re thinking of a tree house consider suspending it from large limbs with cables, like an extremely large bird feeder. You could also build a house on stilts next to a large tree. Position the house so it doesn’t rub on the tree and the tree doesn’t strike the house on stilts. If you’re determined to build your tree house, contact an arborist and a creative carpenter and you may come up with the perfect compromise.

Suffering Sap Suckers?

March 22, 2007

As spring slowly warms up many migratory birds return to their summer territories.

Robins are always seen as a welcome harbinger of spring. One less welcome returnee is the Yellow Bellied Sapsucker. This small member of the woodpecker family can cause big damage to your prized trees. The bird itself is a little larger than a robin and has a bright red cap and white stripes on its head. The balance of its body is black and white with a yellowish tinge to the belly.

This industrious bird has been known to cause damage to a large variety of tree species.

It tends to prefer smooth barked deciduous trees like the linden, aspen and apple, but will frequently attack Scots pine, white pine and other conifers.

The damage caused is very characteristic, small pea sized holes in neat rows horizontally and vertically, sometimes girdling the trunk. These holes fill up with sap and the bird returns periodically to sip up his tasty handy work. Unfortunately the holes injure the tree directly by damaging the vascular system, preventing the flow of sap back down the tree. These holes also allow insects and diseases to enter into the tree and cause further injury.

Sapsuckers are federally protected migratory birds. You can not simply eliminate the problem by eliminating the birds. This would not only be illegal it would create a vacancy in the territory and a new bird will move in and set up shop. If the tree that is being damaged is not particularly valuable you may consider leaving it to the birds and protecting other more valuable trees. Remedies such as applying hardware cloth to the area being excavated or applying tangle foot to the bark to discourage feeding activity, have proven to be effective. Other people tie tinfoil pie pans, blow up owls, or plastic snakes to discourage the Sapsuckers.

If you are growing trees for specimens or timber you may wish to locate the hollow tree the birds are nesting. These birds normally nest in cavities of rotten aspens or other similar, easy to excavate trees. Mark the tree and eliminate it in the winter when the nest is unoccupied. The birds are quite attractive and do frequent suet feeders. If the damage is minor and you can encourage them to feed elsewhere, they can be quite entertaining to watch.

For more information on trees and tree pests contact an ISA Certified Arborist.

The Big Freeze

February 18, 2007

As you look out your window longing for spring take comfort in knowing that your trees are not really frozen. “That’s impossible with the temperature so far below freezing!” you may think. If your trees were frozen in the traditional sense, like your garden tomatoes, they would be dead.

Hardy perennials and trees have three strategies to prevent them from joining their green cousins every fall. An understanding of why your tomatoes are dead will help you realize why your trees are simply dormant.

In the fall when temperatures drop to the freezing point, ice crystals begin to form in the plants cells. While they are pretty to look at in a snow flake, forming inside a living plant cell

the results are devastating. The sharp water crystals puncture the plant cell causing its contents to leak out. The cell dies as a result. What you see is a wet limp leaf or stem that usually turns black. Commercial food production uses a fast or flash freezing to prevent ice crystal formation and keep your vegetables from getting mushy. Trees are by in large composed of water so how can they survive freezing weather?

Trees have several strategies to prevent ice crystal damage. Even the smallest amounts of

dissolved solids in the water in a tree will lower the point at which ice crystals form. This increases the plant’s ability to survive temperatures slightly below freezing. This is the same reason that salty ocean water freezes at a lower temperature than fresh water. In the case of plants, it is the dissolved sugar that prevents the plants from freezing at just below the freezing point of water.

As the temperature decreases the tree must be prepared by moving water out of the exposed plant cells and into areas that don’t freeze, like the roots. This causes the drying of the exposed upper stems and branches as well as concentrating the remaining sugars in the cells to prevent freezing. Much of the moisture remaining in the cells can be shifted to locations just outside the living cell in the intercellular spaces. Once outside the cell there is no danger that water crystallization will damage the cell.

The entire process reverses itself as the weather heats up in spring. Many plants are injured by rapid warming and freezing that can occur in areas that experience extreme changes in temperature. The ability to survive longer unusually warm spells, while not breaking dormancy, is an issue that affects winter hardiness. Plants that bloom or leaf out early in the spring, are more likely to be damaged by spells of unusually warm winter weather. For more information on winter hardiness contact an ISA Certified Arborist.

Bricks in Your Tree

January 14, 2007

The title (of) this month’s article pretty well sums it up. If you had called your tree surgeon as few as 20 years ago you may have ended up with this unlikely remedy. In the past it was standard practice to fill cavities in mature trees with solid materials to “support the tree”. Imagine if you will the surprise of a fellow arborist years later when he cuts into a seemingly solid tree to find it is full of concrete or bricks!

Cavities in trees form when wood dies and decays. Animals and insects will use the weaker rotten wood to form nesting sites or galleries for there colonies. The two most common causes of injury in trees are incorrect pruning and storm injury. Both actions can result in extensive areas of internal decay in otherwise healthy trees. These rotten areas once excavated by animals or insects can be quite large.

It is important to remember two principals when looking at these cavities: a hollow pipe is as strong as a solid rod and the tree has already formed barriers that will limit the spread of further decay. The first principal flies in the face of the thought, you must fill this cavity or the tree will be weak and fail. What really happens when you fill a living dynamic biological system, a tree, with a solid inert mass of concrete is quite predictable. The tree is further damaged by the constant abrasion of the concrete against the inside of the tree. The concrete is also chemically very different than the tree and will increase the moisture level in the cavity. It will also have a caustic injurious effect on the living wood of the tree. The second principle is that trees are living and act to limit the spread of decay in their tissues. Tree cavities are isolated from the living wood tissue in a tree by strong chemical barriers created by the tree when it was originally injured. If you have ever split firewood you will notice a dark staining around old dead branches in the wood. This is the chemical barrier the tree has erected to prevent the rot from spreading from the dead branch to the living tree tissue. These barriers are reinforced and redirected whenever the tree is re-injured. This injury process occurs every time a tree with a filled cavity moves in the wind. This process of creating resistant chemical barriers in wood is very energy expensive for the tree. Trees that do not have the energy to erect or maintain these barriers will be overcome by rot. When this happens the tree will die.

Occasionally trees will develop cavities that fill with water. It is not recommended to drill holes to drain this water as the tree has created barriers to prevent the water and rot from spreading. Drilling holes will further injure the tree and increase the size of the cavity.

So what is the preferred process for dealing with tree cavities? Access the structural strength of the tree. Is it able to stand with the sound tissue that remains? Access the proximity of the tree to potential targets should it fail. Examine the cavity and if necessary remove any loose debris that remains in the cavity with out injuring the living tissue. Monitor the cavity and see if the tree is putting on strong growth around the cavity evidenced by new healthy tissue.

If the tree is not posing an immediate danger to people or structures it may be safe to leave it where it is and continue monitoring it. When in doubt have a Certified Arborist evaluate the condition of the tree and give you an appropriate recommendation.

Christmas Holiday Tree Nuts

December 1, 2006,

This time of year our thoughts turn to the holidays, trees and feasting. While no festive season is complete without the smell of a real home grown tree, tree nuts are also a part of many people’s holiday celebrations. I’m not talking about inviting your arborist over to enjoy holiday cheer, although that’s one way to ensure you will have a certified tree nut in your house!

Almonds, hazelnuts, walnuts and Brazil nuts are the tree nuts associated with this time of year. Although many people enjoy these delicious treats few stop to think of the origins of these delicious treats.

The ancient practice of eating nuts and other fatty foods is tied to the winter solstice festivals of ancient Europe. In the winter days are short and nights are long. Nuts, a food that causes the body to release endorphins, can create a feeling of well being and mirth. In addition nuts increase the amount of serotonin in the brain. In Low serotonin levels in people have been related to despondent, lethargic and irritable behavior. Eating nuts makes you feel happy!

The almonds in your store typically come from California. This fruit of the tree Prunus dulcis,

is known as “sweet almond”. This nut was carried as a ground mixture on the ancient caravan routes between Europe and Asia. Travelers spread this seed from its origins in Mesopotamia to Greece and the entire Mediterranean climate area of Europe. It is a distant relative of stone fruits like peaches and plums.

Hazelnuts typically come from growers in Oregon, although varieties are native to eastern North America right up to the sub arctic. All hazelnuts are from the genus Corylus and are also called filberts. Filberts are native to the higher elevations of the Mediterranean. They are delicious roasted or ground into a flavoring in lamb stews.

Walnuts have been in cultivation for over 8000 years. The Romans referred to walnuts as Jupiter’s royal acorns. The most popular ones we eat are European walnuts grown in California. All walnuts are in the family Jugulans. Locally you can find Jugulans niger, the black walnut. The fruit of this variety is more shell than meat.

The most intriguing nut story goes to the Brazil nut, the nut that a country was named after. Brazil nuts grow only in the intact rain forest of South America. The Brazil nut, Bertholletia excelsa is a major non timber forest product for the peoples of Brazil as well as Peru. These giants of the rain forest can reach 150 feet in height and can be over 800 years old. In the rain forest only one species of bee can pollinate the Brazil nut tree. This bee needs a specific orchid to complete its life cycle. These orchids only row in association with the Brazil nut tree in areas of intact rainforest. The Brazil nuts come in hard pods, harder than the shell of the nut. Only one rodent indigenous to the region can chew through this shell and disperse the seeds. The Brazil nut tree is at the top of this unique ecological web. If one species is missing from this triangle the Brazil nut is doomed.

So if you want to carry on a long holiday tradition, feel good while doing it, and save the rain forest, get a bag of mixed nuts this holiday season. You could invite a certified tree nut to join you, your Arborist.