When A Tree Grows New Bark

The car struck the tree at more than 60 mph. The teenage driver was dead and his girlfriend was in intensive care. The car was wrapped around a tree and the car battery had gone thru a metal garage door about 25 feet from the tree. The 15 inch Cedar Elm was standing straight but had a large wound. A wrecker pulled the car from around the Elm and that doubled the size of the wound. Now we had a wound that involved 80% of the circumference of the tree and was 3 to 4 feet tall. Our client owned the tree and we got the call the next day. When they wait for the insurance appraisers, that call normally takes a week.

Our client asked what it would cost to remove the tree and was amazed when we told her we could save it and that the wound would be covered in a year. She was more surprised when we told her it would only cost 2 hours of labor and 50 gallons of fertilizer. Folks do not expect low costs, especially when the other guys insurance is paying for everything.

Elm as it looks today (2011)

Elm as it looks today (2011)

The client was skeptical, but I was confident in the outcome and she decided to let us repair the tree. Maybe my guarantee to remove the tree at no cost next year if she was not happy with the outcome had a little to do with her decision. I called our production manager and that afternoon he traced some ragged bark and tacked a piece of roofing felt over the wound. We use roofing felt because it is flexible, easy to cut and, unlike black plastic, holds up for the year we want the wound covered. A few days later the tree was fertilized. That’s it, very simple.During the year after the accident, the Elm did not show any signs of stress. Our client removed the roofing felt after about 11 months. The wound was about 90% covered with normal looking bark and with normal functioning cambium under that surface callus. Dr. Dirk Dujesiefken in his ISA PodCast October 2010 states that their studies show that not only do we get normal woody tissue, normal bark, and normal cambium; we also have no discoloration and no decay under the surface callus.

I did my first car damage repair in 1980 on an Arizona Ash. I was Allan Brook’s production manager, had my BS in Forestry and my MS in Arboriculture, had never heard of such a thing, and was pretty sure that Mr. Brook was touched. Back then we covered the wound with roofing felt and sealed the edges with roofing tar or mastic, very messy. I went back every two months, removed a corner of the felt, peeked in and could not believe what I saw. After a year, the Ash had 100% coverage of the wound.

I have since done this to about a dozen trees, mostly Live Oaks, one Pecan, one Red Oak, and have had similar results. The biggest problem is getting to the tree within 3 days, maybe 5 days of the wounding. Victims will wait on the insurance appraisers.

I have not tried this procedure on a limb. The BMP says it will work on a limb. Almost all of the limbs we see that are damaged by vehicles or equipment are too low and need to be removed for clearances. The one time I did have the right situation I did not think about the procedure and lost the opportunity to try it. When you only do something 12 times in 35 years it’s not the first thing to come to mind (I’m sure it has nothing to do with old age!).

Our BMP says you can use plastic or burlap to cover the wound. I like roofing felt because it is easy to work and form, it lasts a year in Texas heat, and it’s hard to see so people leave it alone. Anything that keeps the parenchyma cells moist will work. Painting the wound is not necessary and not recommended, but this procedure will work even if the wound has been painted. We paint the roofing felt to cover the roofing nails and to cover lines that are on the felt.

Take a look at the before and after pictures. This procedure works. Five years after the accident, the Elm is still looking good. One spot on top of one of the major roots did not cover and I am seeing some decay in that area that has me concerned. Give it a try the next time you are asked to be an EMT for a damaged tree and you need to perform Tree-a?ge.

David Vaughan
San Antonio, Texas

What You Should Know About Soils

soil(updated March, 2017)

Soil is more than sand, silt, and clay with some small amount of organic matter.  You may have 3 inches of clay over caliche, or 12 inches of blackland clay, or 5 feet of sand over hardpan. Whatever you have, soil is teaming with life.

Experts estimate that a tablespoon of forest soil contains 6 billion microorganisms consisting of 75,000 species of bacteria, 25,000 species of fungi, 1,000 species of protozoa, and 100 species of nematodes.  And that is not a typo; that is number of species.

James Urban in Up By Roots uses a cup of soil (that’s a handful for me) and has numbers in the billions;    200 billion bacteria, 100,000 meters of fungi (that’s about 60 miles!), 20 million protozoa, 100,000 nematodes, 50 micro arthropods.  That’s not much soil to contain such mind boggling numbers. The numbers are so large, so extreme; I do not think they register with most of us.  It’s hard to imagine how small you have to be to have 200 billion in a handful of soil.

Under good conditions bacteria have the ability to multiply or divide every 20 minutes.  They could quickly overwhelm the soil unless billions of them were consumed every hour.  A protozoa can consume 10,000 bacteria a day and there are 20 million protozoa in a handful of soil.  Nematodes eat bacteria, some protozoa, and a lot of fungi.  Arthropods eat all of the above. Fungi consume nematodes, decompose the bodies of whatever dies, decompose organic matter, and release nutrients from soil particles and rock.  Bacteria also decompose organic matter and release nutrients from soil and rock.  All are completely dependent upon carbon which can only be supplied by plants.

This is the soil food web.  The entire process protects nutrients from leaching out of the root zone of plants by securing nutrients within the bodies of microbes.  Plants and trees are very particular about the nutrients they absorb and prefer nutrients in a form that has been manipulated by microorganisms.  The nutrient needs to be consumed by a bacteria that is then consumed by a protozoa or nematode and then pooped out in the rhizosphere in ion form. The rhizosphere is a small zone of intense biological activity about 2mm wide (1/10th inch) around a root.  Only then is the nutrient in a form that the plant root can absorb.  So bacteria put out enzymes that release nutrients that they absorb. A protozoa consumes the bacteria, uses what it needs and releases the leftovers which have been converted into a form plants can use.  If the waste is released in the rhizosphere, the expanding root is able to pick it up thru diffusion.

In exchange, the plant provides carbon sugars it has produced during photosynthesis.  About 40% of what a tree produces in its leaves is leaked out thru roots to nourish the bacteria and fungi around those roots.  That is a lot of product being leaked, an indication of how much our trees depend upon the micro soil food web.  The bacteria depend upon their sugar daddy and crowd in on the expanding root like pigs at a feeding trough, forming a physical barrier that excludes bad bacteria.  When things are healthy, the bad guys do not have access to the root or to the sugars. When things are right, the good guys out compete the bad guys, limiting the numbers that could cause trouble.

Fungi can also form a physical barrier around a root, so thick that nematodes and other bad guys are excluded. Many of these fungi are mycorrhizae fungi that are attached to the root or have structures inside root cell outer walls.  The tree provides carbon sugars to the mycorrhizae in exchange for water and nutrients, especially phosphorus.  Fungal hyphae can be 1/60th the size of an expanding root and have the ability to get water and nutrients from very small pore spaces in the soil.  Mycorrhizae fungi are able to deposit water and nutrients directly into the plant root where the water and ions move through a cell membrane into root cells.

Fungi eat or consume nematodes.  Some form snares with their hyphae, put out a nematode attractant, and close the snare when a nematode enters the trap. They then grow a special structure that penetrates the sightless worm to consume the groceries.  Other fungi produce a poison that kills the microscopic worm when the toxin touches its mouth. Some use glue to glue trap the worm.

And then there are the arthropods (mites). They are the big guys in this micro world, eating fungi and nematodes and protozoa. And all these guys are pooping nutrients in forms that plants can use. Many of these waste products get picked up and consumed enough times in this soil food web to become fairly stable compounds which are how humates are formed.

Trees and plants are completely in charge of this system.  They have the ability to change the sugars they provide to stimulate certain bacteria or fungi according to their needs.  They change the sugars they produce by season, by temperature, and by moisture levels.  If they need iron, they produce a sugar to stimulate the fungus or bacteria that can provide that need.  Low on water and they stimulate the mycorrhizae fungi to bring in more water.

Bacteria could easily be washed away so they glue themselves to soil particles.  They use organic glues produced from the sugar compounds supplied by plants. These glues are similar to the ones produced by the bacteria in your mouth that cause morning mouth and tartar.  Clay particles tend to be rod shaped and bacteria can glue these end to end forming odd shaped structures that can resemble a snow flake.  This is the smallest soil aggregate and it protects the bacteria and provides space for the slow movement of air and water.  In sandy soils bacteria form cup like aggregates which hold water.

Fungi need to protect their reproductive structures from grazing arthropods, so they weave or glue several of these bacterial soil aggregates together and hide their fruiting structures inside. The glue they use is called glomalin and it is responsible for about 33% of the carbon found in soil when mycorrhizae fungi are present. This forms a larger soil aggregate, still too small to see with anything other than a high powered microscope.  Millions of these are formed within a handful of soil and they are an important, critical component of soil structure.  The movement of nematodes and arthropods create small passages that also provide for the slow movement of air and water.  These are the aggregates we destroy with compaction, plowing, tilling, and double spading our gardens.  Once these small aggregates are eliminated, water or air will not pass through.  If you want your soil to be healthy, you should not see it very often.  Keep your soil covered with plants and undisturbed.

Trees and their roots can get lazy.  When we provide nutrients to plants in forms they can use with very little biological activity, the tree will reduce the exudates it releases, which reduces the population of the good guys and can give the bad guys access to our plants.  It makes plants dependent upon chemical fertilization.  Fertilizers with high salt content (quick release and water soluble) can desiccate bacteria and fungi and can irritate worms causing them to leave the area.

We need to regard soil as a complex system of living organisms and seriously think about becoming microbe farmers, like the trees in a climax forest.  With the exception of pH, the physical properties of soil are not nearly as important to a gardener or arborist as the invisible living microbes occupying the soil. Your top priority in caring for soil should be to protect and preserve the soil food web.

This article was based on the incredible work of Dr. Seuss in his landmark soils manual, Horton Hears a Who with help from Up By Roots by James Urban, The Soil Will Save Us by Kristin Ohlson, Teaming With Microbes by Jeff Lowenfels and Wayne Lewis, the Certified Arborist Study Guide, Teaming With Nutrients by Jeff Lowenfels, and Teaming With Fungi by Jeff Lowenfels.

David M. Vaughan
Certified Arborist TX 0118
Member American Society of Consulting Arborists
Organic Certified, Texas Organic Research Center

Pruning Recommendations

treepruningPRUNING, when properly performed, is beneficial and can reduce the risk of stem and branch failure; provide clearance for structures, vehicles, and pedestrians; improve health and appearance; and improve views.  Improper pruning techniques are harmful for a tree’s health, vigor, stability, and appearance.  A tree that is not pruned, or left natural, can develop low limbs, co-dominant stems, defects such as included bark, and accumulation of dead branches.

Before pruning, determine the reason and objectives that should result.  For example, young trees, trees twenty-five years or younger, are pruned using different objectives than mature tree, trees older than twenty-five years.  On average, young trees should be pruned about seven times during their first twenty-five years after planting.

Remember, when pruning Oak trees you must paint your cuts, this includes all wounds any size, at anytime during the year!  This rule applies for all species of Oak and to wounds made, for example, from a weed eater or lawn mower.  Any latex based paint works well, the color doesn’t matter.

  1. PRUNING YOUNG TREES:  The objectives for pruning young trees are to: 
    • Establish and develop one dominant leader
    • Space main, scaffold limbs
    • Keep low, nonpermanent branches small
    • Select lowest main scaffold branch
    • Prevent all branches from growing larger than half the trunk diameter
    • Maintain a live crown ratio of greater than 60%

    Please Note: Prior to planting your tree, establish the root flare of your tree to ensure it is planted at grade and that there are no girdling roots present.  It is important to visually inspect the root flare of your tree annually and at each stage of pruning to ensure the root flare remains visible and that no girdling roots have developed.

    First Pruning – Pruning at Planting: Trees that are less than four inches in diameter do not have any permanent branches.  It will take many years for the permanent branches to develop.  Shorten or remove all branches competing with the one leader that will make the best main stem.  Remove broken, cracked, damaged or dead branches.  Do not remove more than twenty-five percent of the live foliage at planting.

    Second Pruning – Two Years After Planting: At this point, there still may not be any permanent branches, especially on trees less than four inches in diameter.  In order to establish a dominant leader, shorten or remove all competing leaders and branches four inches in diameter or larger within twelve inches of the largest diameter branches in the top half of the tree.  Shorten, or reduce, low, vigorous branches to improve clearances.

    Third Pruning – Four Years After Planting: Most branches are temporary even four years after planting and will eventually be removed from the tree.  Shorten or remove any leaders competing with the dominant leader you have selected.  Reduce or remove low vigorous branches for clearances.  Continue to space upper canopy branches about twelve inches apart and reduce or remove branches in between.  There should be only one large branch per node.  If limbs are clustered, or have more than one branch per node, select the one branch that will remain and shorten or remove the competing branches.  Do not remove more than thirty-five percent of the live foliage.

    Fourth Pruning: Eight Years After Planting: Shorten or remove any leaders competing with the dominant leader you have selected.  Select the lowest permanent branch and shorten any branches below this limb to reduce their growth.  Branches below the lowest permanent branch should be removed when they are about half the size of the trunk and after the bark in that area of the trunk has become thick and grooved, or once a branch bark ridge has been established.  Continue to space upper canopy branches at twelve to eighteen inches apart and reduce branches in-between.  The goal is to have only one branch per node, no clustered branches.  Do not remove more than twenty-five percent of the live foliage.

    Fifth Pruning – Fourteen Years After Planting: Shorten or remove leaders competing with the dominant leader.  Select several permanent scaffold branches and reduce branches within eighteen to thirty-six inches of these permanent branches.  Shorten or remove branches below the permanent scaffold branches.

    Sixth Pruning – Twenty Years: Shorten or remove leaders competing with the dominant leader.  Continue to identify permanent scaffold limbs and shorten branches that are between these branches, remember the goal is to have one branch per node.  Reduce or remove branches below the first permanent scaffold branch.

    Seventh Pruning – Twenty-five Years: Perform the same procedures as the previous two prunings.

    These seven pruning sessions accomplished within the first twenty-five years after planting will aid trees in developing good structure, enabling them to cope with high winds and most other stresses. Proper planting and good irrigation until the tree is established may allow you to prune less frequently.


    Mature trees are usually pruned to reduce risk of failure and to provide clearances from structures and throughways.  Occasionally mature trees need to be pruned to allow more light to the ground and for the health of the tree.  Ball moss removal is not pruning and should not include the removal of live branches.  The different types of pruning for mature trees can be performed in the entire tree or in sections of the tree depending on what needs to be accomplished.Structural Pruning: Structural pruning either continues young tree pruning or initiates pruning to develop one dominant leader.  Trees with one dominant leader and small, well spaced branches are less likely to suffer mechanical failure, and can more effectively compartmentalize the spread of decay within the tree.Structural pruning selectively favors a single, dominant leader by suppressing competing leaders using reduction cuts.  Reduction cuts shorten stems back to lateral branches at least one-third the diameter of the cut stems.  Reduction cuts may need to be done every few years to encourage more growth in the selected leader, and should be performed on tree species that will become large at maturity to: promote longevity, decrease future maintenance costs, and in order to reduce conditions in the tree that could cause harm to people or property.Thinning: Thinning reduces the density of live branches, increases light penetration to the interior of the canopy and to the ground below the tree, and increases air movement through the canopy for disease control.  Thinning is also performed for safety reasons.  For example, if performed properly, it can reduce the wind-sail effect or aid in weight reduction pruning.  Proper thinning retains the shape of the canopy and does not remove interior living branches.  Removing interior foliage, or lions tailing, has adverse effects on a tree and should be avoided.Thinning should result in an even distribution of branches by removing some of the branches from the edge of the canopy, not from the interior.  This type of pruning should not remove more than about fifteen to twenty percent of live foliage in a mature tree and often five to ten percent is enough.  For young trees, up to twenty-five percent live foliage can be removed without harm.  Thinning is a delicate process that removes small diameter limbs, usually in the one to two inch size.  Once completed, it may be difficult to tell that the tree was pruned and it should have most of its live interior growth.

    Reduction Pruning: In the urban setting, trees often grow larger than the space they can occupy.  Reduction pruning is often used to reduce the size of a tree by decreasing the length of one or more branches.  It is also used for clearances and to reduce risk when a limb has become hazardous.  Reduction pruning reduces size while attempting to maintain a tree’s form.

    When performing reduction cuts, limbs are cut back to their point of origin or back to a lateral branch that is large enough to sustain the limb and to assume apical dominance.  A common rule of thumb is the lateral branch should be at least one third the size of the removed portion; we normally like to select lateral branches at least half the size of the removed branch.  Most of the removed branches will be two to six inches in diameter. Never reduce a landscape tree by topping it! Topping causes a number of problems such as: decay, numerous sprouts, cracks in limbs, root decline, and bark defects, just to name a few!

    Raising or Lifting the Canopy: Low branches are usually not desirable on mature trees in the urban setting.  Low branches can be kept small using reduction cuts until they are removed.  Upright growth from these low, undesirable branches needs to be removed.

    Canopy raising, or lifting, is performed on young and middle aged trees to prevent low, non permanent branches from growing to a large diameter.  These branches are valuable to the tree because they help increase overall growth and they improve trunk taper, which increases trunk strength.  Branches below the lowest permanent branch should be removed when they are about half the size of the trunk and after the bark in that area of the trunk has become thick and grooved, or once a branch bark ridge has been established. Regular reduction cuts suppress limb growth while the branch bark ridge forms, until they are later removed.  This simple technique is less damaging for the tree because it prevents having to remove large limbs at the main stem.

    Crown or Canopy Cleaning: Crown Cleaning includes the removal of dead, diseased, detached, and damaged branches. Crown cleaning is normally performed on middle aged or mature trees for the safety of people and property and to make the tree more attractive.  Crown cleaning can also be used to shorten branches with included bark to reduce the risk of failure and to address limbs with cracks or other structural defects.  A few water sprouts, or “suckers” can be removed but most of the sprouts should remain, removal of all internal sprouts can be very damaging to a mature tree.

  1.  PRUNING PALMS:Palms and cycads need regular pruning to keep them attractive and safe.  Many palms maintain a set number of live fronds.  For palms, a regular turnover of foliage occurs as dying lower fronds are replaced by new ones.  Dead fronds are not harmful to the Palm tree but they are a safety hazard, can provide shelter for all kinds of unwanted pests, and can become a fire hazard.  An excessive amount of older yellow fronds could indicate a nutrient deficiency of either: potassium, magnesium, or manganese.  Determine the cause of the problem because pruning or fertilizing with high nitrogen or the wrong type of fertilizer will only worsen this problem.Before pruning palms, determine the reason you are pruning and the objective you want to accomplish.  Remove dead and dying fronds and developing flowers and fruit.  It is better not to remove live, healthy fronds, however, if you must remove healthy fronds, avoid removing fronds that are growing upward and be careful about removing fronds growing horizontally.  Excessive live frond removal can permanently reduce the set number of fronds a palm maintains.  When removing a frond, sever the frond close to the petiole base.There is little reason to shave or strip the trunk smooth, although it does no harm to the palm.  The pineapple shape crafted at the base of date palms is not necessary for good health.

David Vaughan
San Antonio, Texas


What You Should Know About Oak Wilt

Oak Wilt in Red Oak

Oak Wilt in Red Oak

(updated April 2020)

What is Oak Wilt?

Oak wilt is a vascular wilt disease caused by a fungus that infects the water-conducting tissues of oak trees and causes them to wilt and die. Good health does not improve resistance to this disease. If the oak tree is challenged by oak wilt, it can become infected. Prevention of Oak Wilt is easy. However, it is a very difficult disease to manage after it becomes established.

What causes Oak Wilt?

Oak wilt is caused by the fungus Bretzillia fagacearum formerly known as Ceratocystis fagacearum. In San Antonio and Central Texas, it is mostly a problem in Live Oaks and in Red Oaks such as Spanish, Shumard, and Blackjack. Live Oaks are a particular problem because of the common root system that develops from root sprouting. This connects all of the Live Oaks in an area with a common root system.

Oak wilt moves from location to location by the transport of a spore (a sort of seed) carried on the body of an insect. It travels from a spore mat produced on a Red Oak, to a fresh wound on another oak. The spore does not blow in the wind and cannot be carried by smoke.

Once oak wilt infects a Live Oak, it is moved from tree to tree through the common root system. It can also be carried from tree to tree through root grafts that can be formed between the same species. It is not uncommon for different species of oaks to form root grafts, allowing the disease to move between oak species.

What are the effects of Oak Wilt?

Typical leaf necrosis

Typical leaf necrosis

Leaf symptoms of oak wilt on Live Oaks are distinctive. The veins of the leaf turn yellow or brown while the rest of the leaf is green. We refer to this symptom as veinal necrosis (death of the vein) and it is considered diagnostic, Other symptoms include tip browning and leaf margin browning. These are non-diagnostic symptoms that also occur with other conditions such as drought or chemical burn. Once leaf symptoms occur, Live Oaks generally die within three months to a year. A few Live Oaks can survive for many years in decline. Leaf symptoms are difficult for most people to determine including most tree care companies. As a result, these companies treat trees erroneously or remove trees that are not infected. Buyer, beware! Before you sign a work order, get a confirmation from the Texas Forest Service or from someone that TFS has certified (TOWC, Texas Oak Wilt Certified) or qualified (TOWQ).

Leaf symptoms in Red Oaks are much less distinctive, having none that are considered diagnostic. Red Oaks generally die within 30 days of the appearance of symptoms, leaving little time to react or confirm the disease. During winter and early spring, structures covered with spores can form just below the bark on infected Red Oaks. These structures are called spore mats and they are difficult to find. These spore mats produce the spores that are carried by insects to fresh wounds on other oak trees.

Laboratory tests can be used to confirm Oak Wilt using the sap wood of a suspected oak. Negative results are currently only about 70% accurate. Some labs offer DNA testing to confirm Oak Wilt that is less expensive and faster.

How can Oak Wilt be prevented?

Prevention of Oak Wilt is easy:

  • Paint all pruning cuts and injuries on Oaks.
  • Avoid pruning oaks during the spring.
  • Do not bring contaminated firewood on to your property.

Paint or treat all wounds on Oaks within a few minutes to an hour. Treating Live Oak wounds after three days has no effect. You can use latex paint (our preferred choice), hair spray, Elmer’s glue, mud, shellac, you get the idea. Get the wound covered. The size of the wound does not matter, treat all pruning cuts. If you cannot treat it, do not cut it! Strangely, we do not recommend the use of pruning sealers (except to seal clay pots) because the sealer is too thick and can result in other problems. You can use the cheapest latex spray paint you can find and color is not important. We know of no benefit to painting wounds or cuts on other species of trees, so oaks are the only trees that need treatment.

When possible in San Antonio, avoid pruning oaks during March, April, and May. Those months generally have good conditions for the presence of spore and for high populations of sap feeding insects. That does not mean you cannot prune in those months to remove broken branches or branches that are hitting the roof of your house or car. If you must cut a limb, paint the pruning cut. If you have a choice or if you are doing routine pruning, avoid pruning in the spring. The safest time to prune is during hot weather from June through Thanksgiving or some years thru Christmas. It is also safe during cold weather when insects are inactive. Even during safe times, paint all pruning cuts regardless of size. If you cannot paint it, do not cut it!

The transport of firewood is responsible for many new oak wilt centers. During storage, insects can emerge from the transported wood and infect nearby trees. Or spore mats can form on fresh Red Oak during storage. Burning of the wood is not the problem as oak wilt does not spread in the smoke, and is killed by fire. Firewood cut from trees growing on your property is not a problem. The problem is wood brought in from other locations. A lot of firewood is coming from oak wilt centers where it is cheap or free and easy to obtain. If you can easily remove the bark with your fingers, the wood has cured long enough to be safe. The recommendation to cover suspicious wood with clear plastic to trap or kill insects is not wise. Do not purchase or transport firewood that is not safe. Just like Jurassic Park, life has a way of escaping. If you are going to cover the firewood with clear plastic, it is not safe and you should not buy it or transport it.

What are the Treatments for Oak Wilt?

Oak wilt is not an easy disease to manage once is gets on your property or in your neighborhood. Rarely, we are able to discover the infection in the first tree, before the disease has moved into the root system, and the total removal of that tree stops the disease. Once two or more oaks are involved, trenching usually is the only effective way to contain the disease center. Trenches are installed 100 to 150 feet beyond trees showing symptoms, completely enclosing the infection center. You can imagine the mess, destruction, and coordination problems to accomplishing this. Trenches need to be at least five feet deep. The purpose of the trench is to cut all root connections. The trenches can be filled as soon as they are made.

Fungistat injection

Fungistat injection

Fungicide injection or infusion can protect individual trees.  Often, just a single injection is effective.  If symptoms return after 2 years, the tree needs to be re-treated.  If symptoms do not re-appear, the tree should be fertilized or mulched to help it recover from disease damage.

Injection has some worth as a preventive, but will not stop the movement of the disease through the roots into non protected oaks. Treatment success is not guaranteed. It is expensive and may need to be repeated about every two years. Unless you have a large budget, you need to be selective with the trees you choose to inject and you need to be prepared for some failures.

There are several new generic (less expensive) mixes with propiconazole that have the same percent active ingredient as Alamo. They are causing the cost of Alamo to come down dramatically (yay!).

Our experience with micro-injection has been absolutely dismal. Current research shows no success with micro-injection. We would all like to use this method because it is easy and neat. But, it does not work.

There are other oak wilt treatments being sold, miracle treatments using secret ingredients.  None of them has shown any long term success. Most of them use fertilizer to make a tree look better for a short time and have no effect on oak wilt.

There is promise with Systemically Induced Resistance (SIR) using Trichoderma fungus obtained from whole ground cornmeal to enhance the effect of Propiconazole.  Mix rates are one cup corn meal per gallon of water.  Five gallons for a small tree, ten gallons for a medium tree, and fifteen gallons for a large tree.  I recommend a cornmeal tea drench with all Oak Wilt injections.

The TFS Oak Wilt Suppression Project was designed to assist you with oak wilt management. They expanded this program and are training certified arborists to help them identify the disease and develop management approaches for individual property owners. The original training certified arborist as Texas Oak Wilt Certified (TOWC) and they were listed on their web site, www.texasoakwilt.org. Current training just initiated in 2017 qualifies the arborist as Texas Oak Wilt Qualified and requires retraining or re-qualifying every 5 years.

David M. Vaughan
Certified Arborist TX 0118
TOWC 0061


Tree Vents

tree vent

tree vent

Purpose: To provide air, water and fertilizing ports in the root area of trees that have paving over their root zones. Their main value is to vent toxic gases to the surface and to allow oxygen to enter the soil under the paving. Their secondary value is for water and fertilization. Fertilizer should be applied through the vents annually.

Procedure: Vents can be installed at 6 feet on center to about 10 feet on center. The inner circle is established about 6 feet from exposed soil. The outer circle follows the branch spread of the tree. Interior circles are spaced between these two circles at the chosen spacing distance. A rock drill with a 2.5 inch star bit is used to drill through the paving and base material into the original soil. If paving is concrete, it requires the appropriate drill. The vent sleeve is driven through the pavement and base into the original soil and the vent top is placed in the sleeve. The top will eventually become recessed to grade in asphalt and gravel. It will rest on top of concrete and pavers.