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.

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.

Old Friends

While walking in a friend’s garden the other day I stepped on a stepping stone with the following inscription; “It takes a long time to grow an old friend”.

Trees are long lived organisms that can easily have life spans across human generations. While not all trees live hundreds of years some can live thousands. Large mature trees are adapted to extreme forest environments and threats. There are many strategies to help trees survive various natural catastrophes. For example fire resistant bark, roots that can regenerate after disasters and seeds that take years to germinate are genetic adaptations for survival. These survival strategies don’t always work for the trees in your front yard.

Changes in nature can be sudden or they can take years. Sudden changes include ice and wind storms that rip and tear branches from trees. Lightning, fires and floods also happen quickly. Long term changes that effect tree survival are soil erosion or deposition, encroachment by grass, and competition for light from other trees.

How does this relate to your front yard trees and their survival?

Simply, change requires adaptation and adaptation in trees is pre programmed. If the tree isn’t able to adapt to changes in it environment it declines and dies. If the tree does not have, within its genetic bag of tricks, the ability to survive fire, the tree will die. A burr oak tree, with thick fire resistant bark, would be able to survive a runaway grass fire without major consequences. A thin barked cherry tree would not survive.

If your tree isn’t able to survive changes in grade or soil compaction it will not survive construction of a new addition to your home.

Trees like American elm will survive changes in grade and soil compaction while white oaks will most likely decline as a result of root disturbance.

In the modern world we are able to affect great changes on our landscapes. Heavy equipment can literally move mountains. Why do we expect trees to survive after the mountain has been moved? Obviously we overestimate the ability of trees to survive construction damage. Trees are alive. Damaging roots has serious impacts on plant health. Tree roots are living plant organs that take moisture and nutrients from the soil environment. The top eight inches of soil contains 90% of all tree roots. Take a look at a storm toppled tree and you will see a broad shallow fan of roots.

So when we think of changing our landscape we should consider the impact that these changes will have on our “Old Friends” before we make the changes. If you’re not well versed in the capabilities of your trees contact your arborist well before construction begins. They will be able to help you minimize the impact of changes in your landscape and maximize the survival of all our green friends.

Dedicated to the Preservation of People

October 29, 2006

It is the small stuff that can kill you. And if it doesn’t kill you it can cost you lots.

Having operated a chain saw for 28 years I may be more at risk of injuring myself than

the novice user. There is in arboriculture a phenomenon that leads to headlines like

“experienced operator injured by chainsaw”. It’s called complacency. I had the opportunity to attend a professional chainsaw operator instructor certification course a few years back and was surprised that we would be spending 3 of the 5 days in a hands on field school. I was at the time operating a chainsaw on a daily basis and was confident in my ability to drop the tallest tree with little effort. What I didn’t know was that the smallest tree still requires more than a little thought to land it safely where it should go.

The basic geometry of tree falling has remained unchanged from the Stone Age.

In fact beavers, rodents not known for there cerebral abilities, use the same methods as we do. Cut or chew a notch in the side of the tree that has the greatest lean,

then go to the opposite side and make a back cut. Unfortunately Mr or Mrs Beaver sometimes never return to the lodge, they fall prey to the uncertainty of tree felling and get crushed. I’m not sure what goes through a beavers mind when he is felling a tree

but if you are not focused and concentrating on the basics you may not make it back to the lodge either.

The basic technique with a chainsaw involves making a horizontal cut no more than 1/3 of the way into the tree ninety degrees from the intended direction of fall. The tree generally will fall in the direction it is leaning. The next step is to cut a notch by making a cut on a forty five degree angle from above the first cut to meet in a perfect apex. This cut should not run over, under or behind the first cut. It is called a pie cut because it results in a perfect pie shaped piece. The last cut comes in from behind parallel to and slightly above the first; it should stop before it meets the pie by at least one inch. This small piece of remaining wood is called the hinge or holding wood. It will direct the tree and may save your life.

Any variation from this procedure and you will have problems. What problems?

Lack of control is the primary problem. With a large tree the problem becomes larger. If the hinge is cut incorrectly the tree may fall in an unintended direction. If the hinge is cut through, the tree will fall without control and in any direction. Take the time to review basic tree felling technique and don’t let your mind wander while chain sawing. Each cut involves risk and should be performed with care and caution. If you don’t it could cost you not only your lodge, but your life.

Good Leaf Bad Leaf

Now that the yearly crop of leaves has fallen it may be of interest what to do with them next. In this age of recycling it is all the rage to compost your leaves to recycle the nutrients. Well this is a great idea in principle depending on the trees on your property you may want to reconsider this approach. Back in the good old days people used to burn all there leaves and spread the ashes on there garden. While this practice isn’t the best from an air quality standpoint it does eliminate over wintering disease and insect problems on the leaves that may survive composting or just piling up in the woods. While it’s no longer recommend to burn your leaves, selected recycling and compost may be your best solution.

Trees that have old insect infested fruit, like apples, should have this disposed off site or buried to prevent the insect pests from over wintering in the fallen fruit. Similarly leaves from trees that frequently have outbreaks of fungi like lilacs, dog woods and ash trees should be gathered and thoroughly composted for more than one year away from the affected trees. Many trees have gall or other mites that disfigure the foliage with cocks combs or nipple like lumps. These should be moved off site or disposed of to prevent re-infection. Leaf shredders are an excellent way to speed up the process of composting, mixing leaves with other vegetable waste from the house and turning it frequently will promote proper composting.

Now that leaves have fallen and trees are dormant there are things you can do to help them get through severe winter weather. Even though the tops of your trees look dormant there is plenty of action in the root zone. Ensuring the plants have lots of available water at this time can improve survival when temperatures start to rise in the spring. Fall fertilization and watering your evergreens are two cultural practices that can make a big difference in winter survival and help your trees thrive next spring. Be careful when fall fertilizing follow label directions carefully and use low nitrogen slow released fertilizer. Watering and fertilizing can take place from now until the ground freezes. If you want more information on fall tree care contact an ISA Certified arborist, they are experts on tree care and plant health.

So You Still Want to Plant a Tree

May 17, 2005,

How to dig a fifty dollar hole for a five dollar tree.

The number one mistake made when planting trees is to make the planting hole too small. A properly dug planting hole is broad and shallow, two to three times as wide as the root ball and slightly shallower. It should be dish shaped sloping down to the deepest part below where the plant will sit. Do not place gravel in the bottom of the planting site as this will result in water being trapped in the finer soil on top of the gravel. This is called a perched water table, and often causes root death from drowning. If you site has poor drainage consider installing drain tiles to help improve the situation.

The number two mistake made in planting trees is to plant them too deep.

Roots need to breath, and don’t grow upwards readily. It is much better to plant trees “high and proud” as the saying says, than it is to have buried them in a shallow grave. More than one group of trees of different sizes has been evened up by planting the tallest one a little deeper. Only several years later after the tree has died, does digging it out reveal that it was planted too deep. Roots and tree trunk tissues are adapted to being under and over the soil respectively. The reverse never works. If you see branches coming from below the soil level it’s a tell tale sign that the tree was planted too deep.

Once you have selected your tree and dug your hole its time to put it in the ground.

In the past the most nursery stock was available as bare root, for smaller trees or balled and burlapped for larger landscape feature trees. Container grown trees are a relatively new phenomenon with tremendous advantages, and one big problem. This is the phenomenon of girdling roots. Trees grown in pots will have roots that circle the margin of the pot. When you take the tree out of the pot you will see these roots at the edge of the root ball. It is advised to take a sharp knife and cut these circling roots in a few places around the root ball to limit the chance that they will grow to strangle the trunk of the tree. Girdling roots are much less of a problem with balled and burlapped trees as exposure to air will prune the roots before they get to the edge of the root ball.

Place your tree into the planting hole carefully and fill the soil back into the area surrounding the root ball. The soil should be the same as the soil surrounding the planting site. Mixing back fill soil with peat or sand is not recommended as it creates problems with root penetration beyond the planting hole as the tree grows. The trees roots may never extend past the amended soil. Do not put soil on top of the root ball, don’t bury the trunk. Once your tree is in place and has been backfilled, gently pack the soil around the root ball to eliminate air pockets. Watering after planting is essential to keep the new roots from drying out and to establish a moist link between the planting site and the ground water. If your tree is unstable it may require staking or guying. This subject will take an additional article as it is often done incorrectly. For further advice on tree planting contact an expert, an ISA Certified Arborist.

So You Want to Plant a Tree

May 1, 2005,

The number one mistake made by home owners planting trees is to choose a tree that will be too big for their planting location. Always take into account the mature size of the tree and choose a tree that fits your site. Big site big tree, small site small tree. Look up, way up, are there wires? If so plant a tree that will mature into a small size. Crab apples, cherries, and Asian maples are ideal candidates for small sites. Avoid planting your tree over under ground utilities that may require service or interfere with the roots of the tree. Take our harsh weather into account when planting. All trees moderate the environment and reduce pollution. Large shading deciduous trees planted to the south will shade you from the summer sun while letting winter rays through. Evergreens planted to the north and west can reduce your heating bill. Carefully analyze your site before you select your tree.

Once you have your site conditions figured out chose a tree to fit those conditions. Some trees have a great degree of adaptability to adjust to different site conditions. Shade tolerance, drought tolerance and ability to survive alkaline or flooded soils are just a few potential problems. Adverse site conditions effect the survival of the trees you will plant. Hardiness refers to a trees ability to survive low temperatures. This means not only the minus forty blast of winter but the late frost and May snow storms that we occasionally receive. Native species like the green ash wait until the last frost has passed to send out leaves. Introduced species may be fooled by late winter warm spells. Trees that break dormancy early may be caught with there leaves out too soon. Check to see that the tree you plan to plant is fully hardy. Disease and pest resistance are two areas that must be addressed to avoid disappointment and expensive maintenance in the future. Choose a tree that is healthy and vigorous. Look out for old stock or trees that have just been planted into pots. Once you have crossed all these criteria off the list, you have to pick a tree that has the potential for good branch structure. Be on the look out for weakly attached branches with narrow “v” like crotches. These may fail later in the life of the tree. The process of selecting and promoting permanent branches is easy once you know the basics and will be the topic of a future article. It’s enough to say that all of the branches you have on your 5 to 6 foot tree purchased from the nursery will probably not be there for the life of the tree. Most will be removed while the tree is young for clearance and shaping in the landscape. I guess there is a lot more to planting a tree than just throwing it in a hole!

We will get to actually planting a tree next time, after the snow melts!

The perfect tree

While doing tree research a number of years ago, my supervisor made an interesting

comment. He handed me a legal sized page with tiny numbers and correspondingly minute descriptions. The page was called a defect sheet and I was instructed to use it to assign the appropriate number, to the defects I would encounter while looking at trees on the job.

Being a long way into the forest, surrounded by beautiful trees, I made the following comment “What do I do if I find one without a defect?” “Call me on the radio and I’ll come right out”, he continued grinning “I have done this for years and haven’t seen one yet”. “Look harder, you probably missed something,” he cautioned. Days and months passed and sheets and sheets of data were submitted. Predictably there were no empty boxes on the defect sheet. Trees are long lived immobile organisms. They change and adapt to the seasons and surroundings by the growth or death of their parts.

What we view as defects are the results of these adaptations. From a timber harvesting point of view defects are characteristics of an individual tree that reduce its quality and utility. This could include basal rot, sweeping curves in the trunk, broken tops or excessive branching. These conditions reduce the value of a trees being processed into lumber, pulp or any of a multitude of uses.

Trees plantations are an attempt to minimize the number of defects and increase the value of trees for harvest. Plantation systems require more intensive cultural practices than natural forest systems, and may be more prone to insect and disease outbreaks.

In the urban forest we assume a perplexing set of roles can be filled by trees. Trees have grown and evolved in complex forest communities very different from our yards and wood lots.

We expect them to grow quickly and fill there place in the landscape for many years.

Trees are expected to be disease and problem free in this foreign environment.

It becomes clear that these values are often contradictory.

Keep in mind the environment where a tree originated. Was it a fast growing wetland species? Is your front lawn a similar environment? Perhaps a Birch isn’t the best choice for that location.

In many of our dry landscapes Burr Oak is the ideal tree, but they are seldom planted because they grow very slowly. Trees that grow quickly such as poplars and willows don’t last long. Trees that are planted too close to buildings require long term maintenance and lose their visual appeal as they age. Defects that would be tolerated in the forest become increasingly problematic in the backyard. A curved trunk may be indicative of weak rooting and increased potential for wind throw. Trees in the forest may fail without causing damage to people or property. Failure of landscape trees frequently causes substantial damage.

Take the time to look at the trees in your environment, check them for defects.

Foresters and Woodlot Extension personnel are experts that are available to help with managing trees for timber production. They can help you maximize the utility of your woods.

Similarly an ISA Certified Arborist can help you maximize the utility of your landscape.

In both cases the price paid for an assessment will save larger costs later.

I am still looking for that perfect tree; if you find one please call me I’ll come right out.