The following information will help you understand the Emerald Ash Borer problem that is developing in McLean County. Other resources include the State of Illinois, the agricultural extension service, and local garden supply stores and landscaping maintenance contractors that employ arborists. If you have comments or information that others may find helpful, please use the comment button at the bottom of this page.

Other websites to consult: http://www.emeraldashborer.info/, and http://www.illinoiseab.com/.

FACTORS TO CONSIDER IF YOU HAVE ASH TREES ON OR NEAR YOUR PROPERTY 

Size and condition of the ash tree:

a.       Is the ash tree confirmed with EAB infestation? Such trees should be removed immediately and properly disposed of, as they provide a breeding ground for the EAB to spread to other ash trees. EAB infestations increase at a rate of 10X per year; thus, 1, 10, 100, 1000, 10,000, etc. Even larger trees will suffer irreversible damage after 4-5 years of infestation. Early infestation does not show readily-visible symptoms, and once such symptoms are noted, the infestation is usually advanced and the tree is unlikely to be saved. Go to http://www.illinoiseab.com/ for more information about EAB and its symptoms.

b.      Is the ash tree at high risk of infestation? Currently, there is a substantial risk of infestation of trees in McLean County because of confirmed cases here. However, removal of an ash tree that appears healthy is a difficult decision that requires assessment of alternatives such as treatment in light of the factors contained in this document.

c.       Is it a small ash tree that can be readily replaced with a similarly-sized tree of another species? Given current conditions, it is recommended that such trees be replaced as soon as possible.

d.      Is it a larger ash tree without apparent EAB infestation and otherwise in good health? Such trees are at risk but are candidates for treatment or a wait-and-see approach. Because we are in the early stages of the disease here in McLean County, there is no single answer for ash trees that are not visibly infested but at high risk. If you decide to not remove your ash trees now, we recommend closely monitoring them, the EAB situation in McLean County, and available treatments.

e.       Is it a larger ash tree without apparent EAB infestation but in otherwise poor health? Such trees are already weakened from other causes and less likely to respond to treatment, and could fail to due causes other than EAB, and are thus lesser candidates for treatment and better candidates for removal.

Current and probable future effectiveness of treatments:

a.       Currently available treatments vary in effectiveness. No treatment is fully effective. In an otherwise healthy tree, treatments can be from 35-85% effective. In a tree that is already infested or otherwise unhealthy, effectiveness can vary from 0% to less than 50%.

b.      The Syngenta “Tree-age” (emamectin benzoate)treatment is considered more effective than the “Bayer Advanced” (imidacloprid, also called “Merit”) treatment. Effectiveness research is continuing.

c.       Treatments are most effective for preventing infestation and less effective in reversing infestation. Once a tree is infested, the EAB attacks the tree’s ability to conduct vital fluids to all parts of the tree. Thus, systemic treatments, which depend on the distribution of preventive chemicals through the tree’s circulation system, will become less effective once infestation occurs and especially after infestation advances.

d.      The “Tree-age” treatment must be administered by a certified professional. The “Bayer” treatment is available at retail for “do-it-yourself” use by homeowners (“Bayer Advanced Tree and Shrub Insect Control”). This is usually done by pouring a mixture around the tree, or using a root feeder, to introduce the chemical into the tree roots, where it is absorbed systemically upward.

e.       Research is being conducted into new treatments and there is some possibility that advances may be made, including some possibility that a complete cure may be available sometime in the future. However, there are no guarantees, and waiting for a cure could increase the spread and damage from the disease, and could result in much higher removal costs if the tree must be removed during a critical period. Absent a substantial breakthrough in treatment, the prognosis for ash trees in McLean County, and eventually across the United States, is poor.

Location of the ash tree:

a.       Is the ash tree easily accessible for removal along the parkway or accessible from the street, versus in a back yard or obstructed within a grove of trees? Are there nearby impediments for removal, such as structures, other trees, fences, utility lines, etc.? Is there sufficient space for felling of the tree in larger pieces or must it be removed in smaller pieces from its top down using specialized equipment? These factors influence the difficulty and cost of removal.

b.      Does the ash tree provide important shade, windbreak, soil stability or other important functions?

c.       Is the ash tree in a critical location for property appearance, such as in a key front yard or parkway location where the tree’s presence will readily be missed? A single ash tree on a prominent edge of a corner lot may be more critical to a property’s appearance than an ash tree located behind other trees in a side yard. Trees have influence on the appearance and value of a property.

d.      Is the ash tree located near a street or structure(s), so that the tree’s failure could result in human injury or property damage? This could create legal liability for the tree owner.

e.       Is the tree in proximity to known EAB infestations? EAB can spread, on its own, by up to eight miles per year, and even further if spread by human intervention. Obviously, an ash tree in close proximity to known, advanced infestations is more likely to be infested itself. Once infested, an ash tree becomes less likely to be successfully treatable.

a.       Estimated treatment cost per tree varies, depending on tree size and source, from less than $100 for do-it-yourself “Bayer” application to as much as $300 per tree for professional application of the more effective “Tree-age”. Treatments are usually applied at least once every two years, and the need could continue for many years.

b.      At the present, estimated tree removal costs begin at about $25 per inch of trunk diameter at the base, and can more than double that depending on the provider, quantity of trees, and the location of the tree(s). Correct removal, especially when replanting, should include removal of the stump, which can add additional cost.

c.       As infestation progresses, supply and demand principles will take effect, and costs will likely increase. Earlier removal may prove to be more cost-effective than waiting until infestation is rampant and there is a large demand for tree removal.

d.      Once infestation begins, an exponential increase in damage is likely, especially after 4-5 years. It is estimated that some trees in McLean County were infested over 4 years ago. Trees in Chenoa have shown the most advanced effects, and infestation on both the east and west sides of Bloomington was noted in August, 2008. Given current conditions, this can be expected to spread, possibly resulting in widespread death and removal of ash trees during a short, but intense, period within the next 4-8 years.

e.       Removal of an infested ash tree must include proper disposal of the debris.

f.       Within a quarantined area such as McLean County, removal of any ash tree – whether infested or not – must include proper disposal.

g.      Proper disposal includes an absolute prohibition of the removal of the tree debris from the quarantine area and either: (i) complete burning of the debris where burning is safe and permitted by law, (ii) complete chipping of the tree debris, or (iii) deposit of the debris in an approved disposal facility within the quarantine area. Allowing infested trees to remain standing or not properly disposing of the debris of an infested tree will contribute to the spread of the disease.

h.      Only debris produced by maintenance or removal activities of property owners themselves is eligible for free removal from the parkway by city crews. Debris resulting form the activity of contractors is not eligible for free removal by city crews, and property owners should assure that their contractors include proper removal in their bids and actually do remove any debris.

i.        Because ash tree debris, whether infested or not, requires special disposal, the city will institute special rules and procedures for such debris in the future. If you currently have ash tree debris, including trimmings from healthy ash trees, please call the city’s public service department at 434-2220 to discuss your options.

j.        The City of Bloomington will remove trees on city property, including parkways along streets, at no expense to the owners of adjacent properties. As the property owner, the city reserves the right to use its sole discretion in deciding whether trees should be treated or removed and what priority should be given any treatment or removal; unsafe trees will receive the highest priority. The city maintains an inventory of all its trees, and has identified over 3000 ash trees on its property. Management of any treatment and/or removal will require a careful balancing of public needs with the expenditure of taxpayer funds.

k.      Currently, there is no city ordinance regarding mandatory removal of infested ash trees or preventative removal of non-infested ash trees, although this may be considered in the future. Therefore, owners of those ash trees on their own private property have discretion in their removal, although consultation with neighbors is recommended when trees overhang another’s property. However, city ordinances do regulate trees that jeopardize public safety or property, and any trees deemed unsafe must be promptly removed by their owner, or the city may remove the tree and charge the owner for removal plus fees. Property owners will likely go through a process similar to the city’s when deciding which ash trees to treat or remove, and the risks and timing thereof.

l.        The costs of treatment and removal of trees on private property must be borne by the property owner.

m.    There is a potential liability to property owners for trees on their property that are known, or should be known, to be damaged and potentially dangerous, whether the damage occurs from EAB or other reasons. A dead or visibly dying tree can create legal liability, possibly substantial, for its owner if the tree fails and causes property damage or injury.