Managing Wood-Boring Insects

To keep your trees healthy, one will want to watch out for what is called wood-boring insects. These insects are considered secondary invaders, which means if your tree is already unhealthy, infestation of these insects will only damage them more. So what can you do to avoid these wood-boring creatures? According to the local extension agency, here are a few good horticultural practices:

• Select well-adapted species of trees and shrubs that are not commonly attacked by woodborers in your area. Arizona ash, birch, cottonwood, locust, soft maple, flowering stone fruits (such as peaches and plums), slash pines (in west Texas), willow and poplar are especially prone to borer attack.
• Choose and prepare a good planting site to avoid plant stress, freeze damage, sunscald and windburn.
• Minimize plant stress and use proper watering and fertilization practices.
• Avoid injury to tree trunks from lawn mowers, weed trimmers or construction. 
• Promptly care for wounded or broken plant parts using pruning or wound paint during all but the coldest months of the year.
• Properly thin and prune during colder months.
• Remove and destroy infested, dying or dead plants or plant parts, including fallen limbs.
• Wrap tree trunks and limbs with quarter-inch hardware cloth spaced about 1 1/2 inches from the tree’s surface where woodpecker damage is likely. Sometimes wrapping trunks to prevent borer attack is ineffective and may, under certain conditions, increase the rate of infestation. Using plastic trunk protectors to help prevent injury from lawn mowers and weed trimmers is a good idea.

So what about the use of pesticides, you may ask? Once trees and shrubs are infested, non-chemical options for borer control are limited. One option is to remove and destroy heavily infested or injured plants. Damage sites also can be inspected closely to determine if the larvae stages can be extracted from the plant with a pocketknife, wire or other suitable tool.   Again, it is important to remember that stressed, unhealthy trees can be attacked repeatedly and will need repeated applications of insecticide indefinitely. In most cases this is neither economical nor environmentally justified. When chemical treatments are used, efforts always should be made to improve overall tree health.

Insecticide products registered for borer control are applied as sprays to the trunks and branches, and are non-systemic, residual insecticides (e.g., bendiocarb, carbaryl, chlorpyrifos, endosulfan, es-fenvalerate, f luvalinate, lin-dane, methoxychlor, sumithion). While these products do not kill larvae that have already penetrated the sapwood or heartwood, they will kill adult and larval stages tunneling through the treated bark layer. These are primarily a preventive treatment. Some products (those containing paradichlorobenzene and ethylene dichloride) act as fumigants to repel egg-laying adults or kill accessible larvae.  

Trunk injection products (containing acephate, dicrotophos and oxydemeton-methyl) are registered for treatment of some borers. These products are supposed to work by delivering insecticides into the cambium and phloem tissues where borers feed. These injections are most effective against sap feeding insects and rarely affect woodborer larvae. Research has shown that damage caused by inserting the injection devices into trunks can be significant.

One way to protect your trees is to consider where these wood boring insects are coming from. Most adult woodborers emerge from firewood stored indoors. While most of these insects are not considered harmful, old house borer and powderpost beetles will attack seasoned, dry wood inside the home. Treating firewood with insecticide is both ineffective and potentially dangerous to the homeowner. Wood should be stored outdoors away from the house until just before use. If firewood is infested with borers it can be treated by wrapping it in a tarp and allowing sunlight to heat it. Stacking wood layers in alternate directions will help it dry and reduce areas that can harbor insects.

By practicing these few things, you could save yourself a lot of time and money in protecting your trees.
Andrew Johnson is the owner of Central Texas Tree Care, a leading tree service provider in Central Texas (Travis County and surrounding areas) offering services such as pruning and removals, cabling and bracing as well as arborist reports, diagnostics, pest management, fertilization and Austin tree service trusts. For more information please visit http://www.centraltexastreecare.com.

Drought and Its Effects on Austin Trees

For only the third time since the year 2000, most of Travis County, including Austin, is now experiencing "Exceptional" drought conditions. This is according to the U.S. Drought Monitor that was released on December 4th, 2008.

So what happens to trees and plants during a drought or when they aren’t receiving the amount of water they need? First lets look at how trees use water.

Aside from its role in photosynthesis and other chemical reactions, water plays a significant role in the physical processes of plant growth. The driving mechanism for the transport of water through a plant is transpiration or the evaporation of water from plant leaves. Tiny pores or stomates in leaves control the amount of transpiration. Stomates open and close in response to water availability as well as other internal and external factors. Transpiration occurs as long as stomates are open. Transpiration sets up a negative pressure that drives the movement of water from the soil to the plant and through the plant via the xylem. The movement of water from soil to roots to xylem to leaves to air can be viewed as a continuum. Interruption at any stage of the continuum stops or reduces the flow of water, leading to wilting of leaves.

When drought conditions occur, a trees cell membrane shrinks from the cell wall and may eventually lead to death of the cell. This type of injury can also occur when a build up of road salts or excess fertilizer occurs in the soil environment around plant roots.

During a drought, roots shrink and as the plant continues to lose water via transpiration, water is drawn from root cells resulting in shrinkage of cell membranes. If these conditions persist, the integrity of the cell membrane and the living cell itself may be destroyed.

In the root system of a tree or shrub, the delicate root hairs that extend from epidermal cells and feeder roots at the extremities of the root system are responsible for the bulk of water uptake. Confined to the upper 15 inches or so of the soil profile, they are also the first part of the root system affected by dry soil conditions. With the death of root hairs, the water absorbing capacity of the plant is severely reduced.

The effect of drought is particularly acute for newly transplanted trees and shrubs since they are already devoid of a sizeable portion of their water-absorbing roots - the roots being lost in the digging and transplanting process.

When a tree recognizes a crisis such as with a drought, the first thing it does is close its stomates. Recovery from stomatal closing is slow and may not return to normal for hours, days or weeks despite availability of water.

A secondary problem for a tree when water is reduced is that the tree’s metabolites are reduced. These metabolites helps the tree protect itself from diseases and insects. Sometimes we notice a tree is in bad shape when we see it being attacked by beetles or other types of insects.

Some effects of drought on trees are apparent, and other effects are unseen, though just as damaging. Here are three major damages that drought can do.

1. Dead feeder roots
The fine feeder roots that collect moisture and nutrients for most trees are located within the first 15-18 inches of topsoil. If that soil dries out for a long time, the feeder roots will die. Without feeder roots, the tree cannot effectively absorb nutrients and water, even when it rains again.

2. Reduced photosynthesis
Some trees apparently drop leaves as a drought-survival mechanism. Without leaves (or with fewer leaves,) they lose less moisture through evaporation. However, photosynthesis is reduced when leaves fall prematurely, so there are risks as well as benefits to this drought response.

3. Wilting
Wilting is a visible effect of drought. As leaves dry, turgor pressure in leaf cells decrease causing leaf petiole drooping and leaf blade wilting. The amount of water lost before visible leaf wilting varies by species. Temporary wilting is the visible drooping of leaves during the day followed by rehydration and recovery during the night. Internal water deficits are reduced by morning in time for an additional water deficit to be induced the following day.

Visible symptoms of drought-related decline in plant health may not be evident for weeks, months, or years after the drought event. Further decline will often take place while repairs to root system, photosynthetic apparatus, and morphology are made, again taking months or years depending upon the severity and duration of soil water deficits.

Supplemental watering of trees can be timed to help trees recover water and minimize pest problems on surrounding plants. Watering from dusk to dawn does not increase the normal wet period on plant surfaces since dew usually forms around dusk. Watering during the normal wet period will not change pest/host dynamics. Watering that extends the wet period into the morning or begins the wet period earlier in the evening can initiate many pest problems.

If you detect that your tree has already been damaged from drought, contact your local arborist for an evaluation on what you should do.


Andrew Johnson is the owner of Central Texas Tree Care, a leading tree service provider in Central Texas (Travis County and surrounding areas) offering services such as pruning and removals, cabling and bracing as well as arborist reports, diagnostics, pest management, fertilization and Austin tree service trusts. For more information please visit http://www.centraltexastreecare.com.

Damaged Trees and Damaged Property

If you have trees on your property that are tall, old or have branches that could potentially damage your property or your neighbors, you might want to work on securing those trees. Why? If you are not maintaining your tree and it damages your property, your insurance company could cite you as negligent.

Every policy is different, so ask your insurance provider for clarification if your homeowners’ insurance contract isn't clear. But according to attorneys, you could be held liable if your tree is dying or dead, it falls on your neighbor's property, and you did nothing to prevent property damage. In addition, your neighbor could file a lawsuit against you alleging negligence. If it turns out that you are legally responsible for the damage to your neighbor’s house, your carrier will pay for damages up to your policy limits. Similarly, your neighbor submits a liability claim against your homeowners’ insurance policy. If you can prove you did work to sustain your tree or brace it, you could defend yourself against a negligence accusation.

So what are some other potential scenarios when it comes to trees and homeowners policies?

A snow or ice storm causes a tree or limbs to crash into your home, garage or fence. Most insurance companies will pay for all such damages. They will also pay to have the tree removed. If your tree falls over or a branch breaks and it does not damage anything, insurance companies will not pay to haul your tree away.

A neighbor’s tree falls in your yard and damages your property. If a neighbor’s tree falls in your yard and damages your fence or any buildings, your homeowners’ policy will pay you for damages. If the neighbor was negligent, you could seek reimbursement from their policy. If a tree branch or tree falls from your neighbor’s yard and does not damage anything in your yard, insurance will not cover its removal.

A tree or branch falls on your car and damages it. If a tree or branch within your yard falls on your car, your homeowners policy will not pay for damages. You may want to check with your vehicle’s insurance policy.

Your beautiful tree that you have nurtured for years is damaged by a storm. Homeowners’ policies will not reimburse homeowners for the value of a tree destroyed by storms. Fire, explosions or vandalism, which are considered ‘named perils’ are considered reimbursable events.

What are some other things you should know about trees and homeowner’s policies? Here are some tips from the PCIAA.

* Report your damage as soon as possible.
* Take photographs of the damage. Make a list of everything you want to show the adjuster.
* Know the cost of your deductible. Some policies have a flat dollar amount deductible while others depend on a percentage of the home's value. Some claims may not be worth making.

Andrew Johnson is the owner of Central Texas Tree Care, a leading tree service provider in Central Texas (Travis County and surrounding areas) offering services such as pruning and removals, cabling and bracing as well as arborist reports, diagnostics, pest management, fertilization and Austin tree service trusts. For more information please visit http://www.centraltexastreecare.com.

How Trees Heal after Tree Trimming: Austin

Trees are exposed to inevitable damage, whether it is from animals, nature, humans or weather. If you have a damaged tree or if you have done some tree trimming, you may be curious as to how your trees will heal.
Trees have the ability to heal themselves, especially if the damage is minimal. This is true for trimmed trees if the tree trimmer did it correctly. Irreparable damage can occur if a tree is over trimmed or if limbs are cut in the inappropriate locations. Trees that are extensively damaged can become hazards to life and property, and may need to be removed. Consult with a tree conservationist, or certified Arborist to see if a damaged tree needs intervention to be healed, or if it would be better off removed from its location.
Injured trees are susceptible to damage by insects and fungi. Bark normally performs this protective function, but when it is stripped away, the tree becomes vulnerable. Fungi, insects and even weather can cause the tree to quickly deteriorate. Instead of rotting away, trees will try to heal the area by sealing off the damage from healthy portions of the tree. This is called compartmentalization.
Compartmentalization creates a scar on the tree’s surface that helps it to keep susceptible damaged tissues from spreading decay to the functioning parts of the tree. The functional parts deliver nutrients and water all over the tree. Different trees may compartmentalize in different ways and at different rates. The age of the tree and the tree species can have bearing on how the tree heals. Even the weather or season can have an effect.
This is why you should consider hiring an Arborist to do your tree trimming, instead of attempting to do it yourself or hiring someone that may not be thoroughly trained on these types of details. It could be the difference in life or death for your tree. If someone does not know what they are doing, they could cut limbs too close to the veins of the tree causing irreparable damage and essentially leaving the tree open to disease, fungi, dehydration, death or infestation.
After your tree has sustained damage or has been trimmed, you may notice the compartmentalization occurring within a few days or weeks. It looks like a scar protruding from the surface. Once the living tissues are contained, your tree should be safe. If you live in an area, such as Texas, where trees can be scarce or considered a precious resource not easily replaced, then you should really consider hiring a professional before trimming your trees. This is even more important in harsh climates where open wounds can allow a tree to lose all of its moisture. If you are looking for tree trimming Austin, make sure that you hire a certified Arborist to avoid losing your trees.

About the Author: Andrew Johnson is the owner of Central Texas Tree Care, a leading tree service provider in Central Texas (Travis County and surrounding areas) offering services such as pruning and removals, cabling and bracing as well as arborist reports, diagnostics, pest management, fertilization and Austin tree service trusts. For more information please visit http://www.centraltexastreecare.com.

How Trees Respond to Damage

Trees have inhabited the earth since prehistoric times, and have adapted to survive in some of the harshest of conditions. Throughout their existence, trees have been the subject of damage brought on by inclement weather as well as birds and other animals. In modern times, trees are faced with an increased threat of damage as a result of human activities. Unlike animals, trees do not have a process of healing damaged tissue, or in other words, trees cannot replace damaged tissue with healthy tissue. Instead they have developed a way to seal off a damaged area to protect against further damage through a process called compartmentalization.

If a tree is on the receiving end of a vehicle accident, for instance, its bark will likely incur some damage from the impact. With the protective boundary of bark compromised, the wood comprising the interior of the tree becomes vulnerable to harmful insects and fungi. Without the ability to create a protective barrier around the damaged area, the tree would be faced with death and decay. Instead, a damaged tree will begin to seal off the wound area in order to protect the rest of the tree. New bark forming around the wound is referred to as callous tissue, and this new protective tissue serves to protect the rest of the tree from damage as well as prevent it from drying out. If you have ever seen a tree with what appears to be an abnormal growth protruding from its trunk, you have probably seen firsthand the result of this natural defense. Being struck by a vehicle is an extreme incident through which a tree can incur damage, though other forces such as birds, squirrels, storms and pruning are more common culprits for tree damage.

Although trees are equipped with an ability to seal off wounded areas, all trees do not survive after damage leaves them susceptible to infestation and decay. It can take a tree several years to fully seal off a wounded area, and further damage may occur before the area is fully covered by the new layer of protective tissue. Many factors contribute to a tree’s ability to successfully repair a wound, such as the tree’s age, species, extent of damage, and weather conditions. If the wound is compartmentalized successfully without further damage or decay, the tree is likely to survive.

If a tree on your property has incurred damage, it is advised to hire a tree service professional to assess the extent of damage. While trees with minimal damage may repair themselves naturally without intervention, excessively damaged trees may need to be removed so that they do not become a hazard.

About the Author: Andrew Johnson is the owner of Central Texas Tree Care, a leading Austin tree service provider in Central Texas (Travis County and surrounding areas). Central Texas Tree Care offers services such as pruning and removals, cabling and bracing as well as arborist reports, diagnostics, pest management and fertilization. For more information please visit http://www.centraltexastreecare.com.