The Emerald Ash Borer has been widely publicized as a serious threat to Michigan ash trees. Indeed, this pest is spreading northward from the core area in southeastern Michigan and outward from localized outbreak areas at an alarming rate. Emerald ash borers have now been found in Saginaw, Bay City, Mount Pleasant, and on June 19, 2008 in Midland. If you have ash trees in your landscape, you will have some decisions to make regarding those trees.
The pest is not selective when it comes to ash trees. It will attack them and ultimately kill them, unless they are protected. Fortunately, there are very effective preventive treatments available. Imidacloprid, administered by tree IV injection, has proven very useful in prevention of ash borer infestation and treatment of trees which are not severely damaged by the borer.
2008 will be our fourth year using the Arborjet Tree IV and our fifth year using Imidacloprid by injection for this problem. We have used imidacloprid for many years to successfully prevent Bronze Birch Borer infestation in ornamental birches. Among the ash trees we have treated with the tree IV, none of the healthy ones have become infested and the trees which were already infested have at least stayed the same with no worsening or have improved. We have treated several hundred ash trees and none have died from Emerald Ash Borers.
GREAT NEW CHEMICAL! We now have and are using the newest chemical for Emerald Ash Borer control. Tree-age, (emamectin benzoate), has been tested by Michigan State University researchers and found to protect ash trees with 99 to 100% kill rate on Emerald Ash borer adults and larvae. We will be using this chemical for ash borer prevention, unless the ash trees also have lecanium scale. If scale is also present, we will be using imidacloprid, because it also kills scale insects with a high degree of efficiency.
There are several methods of administering imidacloprid, but we believe the tree IV is the very best, based on the research and on our own experience. The tree IV is currently the only way to administer the new chemical. These treatments give two years of control with one treatment and give both better control and longer lasting control than any other method.
Current Recommendations
1. Valuable ash trees should be treated before infestation if possible. Trees larger than 6 inch trunk diameter should be treated by trunk injection.
2. If ash trees are showing thinning, defoliation and/or branch dieback, they may be salvaged if damage is not severe. Injection plus fertilization may be needed.
3. Injection with emamectin using the tree IV should be done every two years to prevent initial infestation or further infestation or damage. OR if scale infestation is present, Imidacloprid should be injected with the tree IV every 18 months to two years. (Every 18 months in high pressure areas with many dying ash trees and high ash borer populations, every 24 months in lower pressure areas with lower ash borer populations.)
4. Trees smaller than 6 inch trunk diameter may be treated by basal soil drench or ground injection using imidacloprid. Homeowners can treat the small trees with imidacloprid available from garden centers.
5. The cost (see below) varies based on the chemical used and tree size because larger trees need higher dosage per trunk diameter inch. Usual cost is 7 to 16 dollars per trunk diameter inch. It is usually far less expensive to treat the tree to keep it alive than to pay to have it removed when it dies.
6. CAUTION! Not all treatments are created equal. The only homeowner treatment that should be used is imidacloprid ground drench on trees under 6 inch diameter. Sprays are not effective for either ash borers or scale. Trunk injection by micro-infusion, specifically with the Arborjet system is proven to be superior to other methods. Lawn care companies and companies with not certified arborists on staff may not be using the optimal methods. Find a company with Certified Arborists guiding the treatments or doing the treatments.
COST OF ASH BORER INJECTIONS
The six year cost of injections for ash borer prevention and treatment is about the same for either chemical, imidacloprid and emamectin. The choice of chemical to use depends on secondary pests: imidacloprid will kill lecanium scale often found on ash trees, emamectin will kill the mites that cause ash flower galls and will kill other types of borers sometimes seen in ash trees.
EMAMECTIN (TREE-Age) charge for treatment is 13 to 16 dollars per trunk diameter inch. The chemical is expensive and the time involved for the tree to absorb the infusion is lengthy at times. The treatment should be done every two years.
IMIDACLOPRID (IMAJET) charge for treatment is 7 to 11 dollars per trunk diameter inch for ash trees. The chemical is less expensive than emamectin and infuses more rapidly. This has a two year duration, except in high pressure areas (see above). In high pressure areas, the treatment should be done in spring of one year, fall of the next, and then a year can be skipped (for example, treat spring 2008, fall 2009 and skip 2010, then spring 2011, fall 2012, skip 2013.
BOTTOM LINE COST amounts to about 7 dollars per trunk diameter inch per year to provide optimal control of ash borers and other ash pests. So a 10 inch ash tree costs about 70 dollars per year to keep alive and healthy. Compare that to the cost of having the tree removed- 350 to 700 dollars, depending on location. So you can keep the tree healthy for 5 to 10 years for the same cost as having it removed.
FREE ESTIMATE OF COST OF TREATMENT. We can come and measure your trees to give you an estimate of the cost of treatment and advise you as to which chemical should be used. Or, you can measure your trees yourself by measuring around the tree (circumference) at chest height and dividing the measurement by 3.14 to arrive at the diameter. Then multiply that number by 7 to determine the annual dollar cost of treating that tree.
GUARANTEED EFFICACY. We are so confident in both products mentioned above that we offer a money back guarantee. If any tree we treat dies of Emerald Ash Borer infestation, we will refund the cost of treatment. This warranty is good for the recommended duration of action and circumstances noted above. So far, we have never had to refund money because we have not lost any of several hundred ashes treated over the past 5 years.
