Archive for August, 2011

This is a question that our salespeople and technicians get asked quite often.

The quick answer is YES.  As can be read in other posts such as Our process to protect valuable ash trees, the method that we use keeps the formulation within the system of the tree.  The formulation is injected into the tree trunk via small plugs, which act as one-way valves, and it stays in the tree.

Other systems such as soil drenching, put pesticides into the environment.  In a letter to the USDA, concerned citizens in Pesticide Action Network North America, Toxics Action Network, and The SafeLawns Foundation, stated the  following with respect to soil drenching.

“…we believe direct soil applications of imidacloprid presents the vast potential for too many unintended consequences. Among imidacloprid’s known deleterious impacts are known to be:
a) Toxicity to birds, fish, crustaceans, earthworms and most especially honeybees, which are essential for the pollination of vast amounts of the world’s food;
b) Potential for migration into water. Imidacloprid can persist in soil for 26.5 to 229 days in soil and has been detected in both ground and surface water in New York. California put imidacloprid on its groundwater protection list due to its potential to contaminate groundwater;
c) Potential impacts to humans. Imidacloprid has been linked in animal studies to reproductive, mutagenic and neurotoxic effects.
d) Several nations, including France and Germany, have banned soil-based applications of imidacloprid due to its aforementioned toxicity issues.”

Although the article is specifically about the Asian Longhorned Beetle, the same process and pesticide is used by some companies for Emerald Ash Borer.  Therefore it is important to ask any company that may treat your ash trees what is the method they use, and what chemical they use.

It is also noteworthy that TREE-age (ememectin benzoate) is more effective over a longer period of time than imidacloprid.  See past post Insecticide Options for Treating Emerald Ash Borer

The complete letter, and associated article, can be read on the following link…

Government Considers Soil Drenching of Pesticides in Boston

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The treatment of ash trees for Emerald Ash Borer varies according to product and method.

The previous post, Best time to treat ash trees for Emerald Ash Borer, describes the differences in treatment methods for Imidacloprid and Tree-äge.  These are soil drenching (Imidacloprid) and trunk injection (Tree- äge).

For Tree-äge, the treatment frequency is every two years in Cincinnati, because most of Greater Cincinnati is considered a “hot zone.”

Studies on population biology by scientists such as Dr. David Smitley of Michigan State University, indicate that within five years of the trees dying in an area due to Emerald Ash Borer, the population of the insect crashes because they now have no food to sustain reproductive capacity. The population falls, the infestation moves on, but the protected ash trees survive! At that point intervals between treatments can be increased, further reducing the overall cost of treatment.

As mentioned, the success of treatment for Emerald Ash Borer is enhanced by Pneumatic Vertical Mulching.  See post “Why We Recommend Pneumatic Vertical Mulching and Fertilizing” for further detail.

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Over the past few weeks many people in Cincinnati have asked when the best time is to treat their ash trees for the Emerald Ash Borer.  Several mentioned that they had heard that April was best, and some said a friend told them that is was too late in the season to treat ash trees for Emerald Ash Borer.

In order to answer this question we need to be aware of two variables; the life cycle of the Emerald Ash Borer, and the type of treatment used.

The adult beetle emerges starting early May, leaving its distinctive “D” shaped exit hole 1/8th inch in diameter.  Adult beetles continue to emerge through June. Eggs are laid starting mid May and continue through  to August.  These eggs take seven to ten days to hatch.  The larvae then tunnels under the bark and starts feeding.  This is the highly destructive phase of the cycle and lasts through October.  The larvae pupates over winter and in early spring the adults start to emerge.

There are several treatment types.  Two of the most common are soil drenching and injection.

Soil drenching: A channel is dug around the tree and filled with imidacloprid formulation.  This takes four to eight weeks to be absorbed into the root system and take effect.  That’s why some say April treatment is best, because the soil drenched tree will be ready for the emergence of the adults in May, and continue to kill the larvae through the fall. Because of the delay in soil drenching taking effect, treating later in the year is less effective. Also, this method need to be repeated every year.

Read about the unintended consequences of soil drenching.

Injection:  The solution that Back Tree Service uses is tree injection with TREE-age.  This has the advantages of taking effect within only 72 hours and remains effective for two years.   Therefore injecting late in the cycle is just as effective as in the beginning of the cycle.

Therefore, the answer to the question on the best time to treat for Emerald Ash Borer is Spring though Fall with TREE-age when the leaves are on the trees.  Let’s face it, if the trees are getting consumed right now, why put off treating it until next year?  Once the ash borer infests an ash tree, it takes only two to three years to kill that tree.  So the earlier they are treated, the less damage to the tree.

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When treating ash trees in the Cincinnati and Dayton area, a question that we are commonly asked is “What is your process to protect ash trees from the Emerald Ash Borer?”

This is a good question and has many people curious to learn the answer.


As you may already be aware, we inject the ash tree with a special solution of Emamectin Benzoate, called TREE-äge.  But how exactly is that done?

Well, we use small plugs that are placed in the trunk around the tree, and approximately six inches apart.  To do this, we drill the holes into the trunk two inches deep and close to the base, maybe a foot or two from the ground.  The plugs are then tapped into the holes, and set.  These plugs are then injected with the TREE- äge formulation.

Arbor Plugs

Plug Placement








In order to determine how many plugs to install, and how much TREE-äge to inject, the first step is to measure the diameter of the tree at 4.5 feet above the ground.  This is called Diameter at Breast Height, or DBH.  Some people are fascinated that we use a special tape measure that has the linear measurement already divided by Pi to give the diameter.

Once we have the DBH, a chart is consulted that shows how many plugs, called sites, are to be put in the tree, and how much TREE-äge per site.  As one might expect, the larger the tree’s diameter, the more sites (plugs) it needs and the more TREE-äge it needs per site.

For example, a six inch ash tree would have three sites at six milliliters of TREE-äge each, an 18 inch ash tree nine sites at nine milliliters, and a 32 inch diameter ash tree would take 17 sites at 15 milliliters per site.

The key is to get the right amount of TREE-äge into the tree.  And, under ideal conditions, the formulation will be up in the twigs in 72 hours.

The Emerald Ash Borer larvae feed on the inner bark of the ash tree.  Any larvae are exterminated by the TREE-äge formulation on contact.

This ash tree treatment has been proven effective for two years, and so we contact our clients every two years in order to renew the protection of their trees.

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