Gypsy Moths and Trees

It's hard to believe that a small moth can be so deadly to something as hardy and large as a tree and yet the gypsy moth is one of North America's most devastating forest pests.
What does the gypsy moth primarily feed on? Typically its most common hosts are oaks and aspen but they have been known to feed on the foliage of hundreds of species of plants in North America with the highest concentrations of host trees are in the southern Appalachians, the Ozarks, and in the northern Lake States.
This moth becomes powerful due to its numbers. It lays its eggs in masses, typically on branches and trunks of tree. The egg clusters are buff in color when first laid but may bleach out over the winter months when exposed to direct sunlight and weathering. Egg clusters contain from a couple of hundred to about 1200 eggs, although some batches may be as small as 50 eggs. Gypsy moths are dispersed in two ways; the first is through wind carrying newly hatched larvae hanging from host trees on silken threads. Larvae can travel for up to one mile with eggs carried even longer distances. Artificial dispersal occurs when people accidentally transport gypsy moth eggs thousands of miles from infested areas on cars and recreational vehicles, firewood, household goods, and other personal possessions. Females are flightless in most varieties, so these are the only means of spreading.
Tree damage is caused when the insect larvae, or caterpillars, emerge from their eggs to the leaves of trees and begin to eat them. The feeding occurs mostly at night. The gypsy moth caterpillar has a special preference for the leaves of deciduous hardwood trees such as maple, elm, and particularly oak.  They can also feed on apple, alder, birch, poplar and willow trees.  As the moth grows it will also attack evergreens like pines and spruces.  Gypsy moths appear to dislike ashes, sycamores, butternuts, black walnuts, dogwoods and balsams.  However, during heavy infestations, competition for food will drive the caterpillar to attack almost any tree or shrub.
Depending on the degree of infestation, tree damage ranges from light to almost complete defoliation.  Most deciduous trees can survive a moderate degree of defoliation.  Many can even survive one complete defoliation by the gypsy moth caterpillar.  However, continuing attacks can fatally weaken a tree or leave it vulnerable to other insects or disease. The condition of the tree at the time it is defoliated, the number of consecutive defoliations, available soil moisture, and the species of host will determine if the tree continues to live or dies. If less than 50 percent of their crown is defoliated, most hardwoods will experience only a slight reduction (or loss) in radial growth. If more than 50 percent of their crown is defoliated, most hardwoods will refoliate or produce a second flush of foliage by midsummer. Healthy trees can usually withstand one or two consecutive defoliations of greater than 50 percent. Trees that have been weakened by previous defoliation or been subjected to other stresses such as droughts are frequently killed after a single defoliation of more than 50 percent.
A number of tactics have the potential to minimize damage from gypsy moth infestations and to contain or maintain gypsy moth populations at levels considered tolerable. These tactics include monitoring gypsy moth populations, maintaining the health and vigor of trees, discouraging gypsy moth survival, and treating with insecticides to kill larvae and protect tree foliage. The tactic or combination of tactics used will depend on the condition of the site and of the tree or stand and the level of the gypsy moth population.
Yes, believe it or not this small insect can cause this much damage. If you think your trees have been infested by gypsy moths, call your local agricultural cooperative agency or arborist to find out what you can do to stop the damage.

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.

Misinformation About Tree Care

When it comes to caring for our trees, many of us rely on information passed down to us from our family or friends. The problem with this is that many times this information can be wrong and many do not find out until it is too late. So what are some common beliefs about trees that aren't true?
COMMON BELIEF #1: Securely stake your new tree when planting it so that it develops stable root system and strong trunk. Staking trees can be necessary at times just to keep them upright and to let them get established when first planted, but professionals have discovered that unstaked trees tend to develop a more extensive root system and better trunk taper than those that are staked. Allowing a small amount of movement can help root and trunk development. Of course, the worst effect of staking is the possibility of trunk damage from the staking wires or ties. Staking materials usually should be removed after one year to avoid "girdling" the tree.
COMMON BELIEF #2: You should wrap your tree trunks to prevent insect entry or sunscald. Generations of people have been wrapping their tree trunks for years, sometimes with kraft paper.  Studies using most common tree wraps have shown that they do not prevent extreme fluctuations in temperature on the bark. In some cases, the temperature extremes are worse. Also, tree wraps have proven quite ineffective in preventing insect entry. In fact, some insects like to burrow under it. If you feel an absolute need to protect your thinbarked trees, such as ash, birch, linden or maple, a loose fitting tree guard in a light-reflective color would be better than a trunk wrap. 
As with tree staking, trunk guards should be inspected periodically to make sure they aren’t restricting the trunk.  Most guards can be removed six to twelve months after the tree is planted.  Always remove wraps that come with a new tree.  It was there to protect the bark during transport.
COMMON BELIEF #3: Pruning trees heavily compensates for the loss of roots. Although pruning the top can reduce the amount of water that evaporates from the leaves, the tree needs a full crown to produce the much-needed food and the plant hormones that induce root growth. The tree will develop a stronger, more extensive root system if it has a fuller crown. Limit pruning at the time of planting to structural training and the removal of damaged branches.
COMMON BELIEF #4: When removing a branch from a tree, the final cut should be flush with the stem to optimize healing. The old practice of pruning tree branches was to cut flush with the tree trunk. When this is done the ability of the tree to stop decay is greatly decreased. Flush-cut pruning cuts into the wood of the trunk cause a wound that can allow decay organisms to infect the main trunk of the tree. The current recommendation is to prune the branch to just outside the collar. Properly pruned branches will have a circular closure around the wound. When the branch is cut too close to the trunk, the closure will be oval or distorted.
COMMON BELIEF #5: After pruning, wounds should be dressed or painted. Research has shown that painting wounds does not prevent wood decay behind the pruning cut and may even increase the amount of wood rot by keeping the environment moist and dark.  It's better to keep the wound open to air and light.  Sometimes pruning paints are applied for cosmetic purposes.  When this is done, they should only be applied in a thin coat.
COMMON BELIEF #6: Certain fast-growing, weak-wooded trees such as silver maple and Siberian elm should be "topped" to make them less hazardous in the landscape. While topping these trees may reduce the potential hazard at first, they will likely be more dangerous in the future. Topping starves a tree by reducing the amount of leaf surface and thereby reducing the tree’s ability to manufacture food for root growth, tree health, and tree vigor. Topping also stimulates growth of twigs below the cuts. Within 2-5 years after topping a tree, it will regain its height but with weaker limbs.
COMMON BELIEF #7: If certain species of trees are pruned early in the spring, they will "bleed," stressing the tree and causing health problems. True, some trees such as maples and birches will "bleed" or lose sap from pruning cuts made early in the spring. This bleeding does not hurt the tree, and the loss of sap is inconsequential. With a few exceptions, most routine pruning can be done anytime of year. The worst time is just as the tree has leafed out in the spring. The best time is when the tree is dormant. To maximize flowering for the following year, prune just after bloom this year.
COMMON BELIEF #8: The root system of a tree is a mirror image of the top. Many people envision a large, branching taproot growing deep into the soil. Actually, taproots are very uncommon in mature trees. If taproots do develop, they usually will be forced into horizontal growth when they encounter hard subsoils beneath the surface. The entire root systems of most trees can be found within three feet of soil. The spread of the root system however, can be very extensive, often extending 2-3 times the spread of the crown.

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.

Proper Mulching Techniques

Mulching around your trees provides a good way to conserve moisture for your tree and keep plants healthy. Trees lose moisture from evaporation, mulching can conserve between 10 to 25 percent. They also help keep the soil well aerated by reducing soil compaction that results when raindrops hit the soil. Having the soil aerated in turn then reduces runoff and erosion. Mulch also helps keep the soil healthy, preventing possible fungi from causing soil-borne diseases.

Because trees sustain a lot of damage from lawn mowing and weed trimmers, adding mulch around the base of your trees can help reduce this damage. Professionals suggest a 2- to 4-inch layer. This will also help prevent most weeds from growing.

When applying your mulch, try and cover as much of the root zone as possible. The mulched area should extend at least 3 to 6 feet out from the base of the plant. Some suggest not putting the mulch right up against the base of the tree, leaving 1 to 2 inches - this can help prevent bark decay.

As far as how much mulch depth to build around your tree, this will depend on the type of soil surrounding it. Sandy soils dry out quickly and often benefit from a slightly deeper mulch layer (3 to 4 inches). A site that stays moist may not benefit from mulching at all.

You can apply your mulch any time of the year, but the most ideal is in late spring after the soil has warmed. Early spring application will delay soil warming and possibly plant growth. You do not have to remove the mulch when you fertilize, just apply the fertilizer over the mulch and the nutrients will move with water to the roots below.

In regards to what you can use for mulch, there are many materials out there - each with their advantages and disadvantages. Organic materials used for mulch should be weed-free. Some of the best organic materials include pine bark nuggets, pine straw, and compost. Pine straw looks nice and will remain in place better than most other materials but Pine bark lasts longer and can be washed with a heavy rain. Bark used as mulch should contain less than 10 percent wood fiber.

Other organic materials that are sometimes used as mulch include wheat straw, shredded newspaper, peanut hulls, wood chips, sawdust, and partially decomposed leaves. Any fresh, light-colored, unweathered organic mulch will tie up nitrogen during the early stages of decomposition.

Non-shredded leaves and grass clippings can form a thick mat that makes water penetration nearly impossible. If sawdust is used it should be well aged, otherwise it will be difficult for water to move into the soil. Uncomposted sawdust is low in nitrogen and will rob nitrogen from the soil as it decomposes.


With inorganic mulches, which include various types of stone, lava rock, pulverized rubber, geotextile fabrics, and other materials - they do not decompose and do not need to be replenished often. On the other hand, they do not improve soil structure, add organic materials, or provide nutrients. For these reasons, most horticulturists and arborists prefer organic mulches.

Mulching has many benefits to keeping your tree healthy and strong. If you have questions about the types of mulch to apply, ask your local arborist or even gardening center.

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.