Since it was first discovered in 2002, Emerald ash borer has killed tens of millions of ash trees. Minnesota has one of the highest populations of ash trees (900 million) in the United States. Unfortunately, EAB was found in Minnesota in 2009 in St. Paul. An integrated approach to EAB management needs to be in place combining ash inventories, strategic removal and replacement, insecticide treatments and conservation efforts.
A Warning Regarding EAB Information
Because Emerald ash borer has only been in the U.S. for less than 10 years, much of the initial information regarding EAB and treatment options was based on incorrect research and data. Also, interest groups such as chemical companies, EAB equipment companies, and environmental groups have promoted EAB information geared towards their personal agendas. Fortunately, a greater understanding of EAB has been gained in the past few years. No one truly knows what the impact of EAB will be in Minnesota, but new research and evaluation will help us make better decisions than were made in Detroit and other areas that were devastated.
Ash Conservation vs. Ash Removal
Picture shows a Treecology Arborist inspecting a local ash tree for evidence of Emerald ash borers.
After its initial discovery, regulatory agencies attempts were made to eradicate EAB through removal and destruction of all ash trees in infested areas. Unfortunately, this proved unsuccessful and other options were explored. Despite availability of cost-effective treatments, many municipalities, property managers, and homeowners continue to rationalize tree removal as the only viable management strategy for EAB. These decisions were based on misguided beliefs that tree removal slows the spread of EAB, or that treatment is not effective, economical, or environmentally sound.
EAB Treatment Basics
Many factors are involved when determining what approach is most successful. Here are some basics to consider:
- Even though EAB was not discovered in Minnesota until 2009, it was thought to be here for several years prior to its initial discovery
- Any ash tree within 15 miles of an infection site is potentially at risk
- Ash trees that are unhealthy or having poor structure should be removed
- If an ash tree has more than 50% of its crown infested, it is too late to treat
- Preventive treatments are more successful for healthier trees since they will have better uptake of chemical
Deciding to Treat Ash Trees
The economic and environmental aspects of treating ash tree are complicated and many factors should be discussed.
- Cost of the insecticide treatment
- Your tolerance for pesticide usage
- Size and location of tree
- Importance of the ash tree
- Health and structure
- Potential cost of removal and replacement
- Environmental impact
Insecticide Options for EAB
There are several type of chemical appications that will work for EAB including soil applications, trunk injections and trunk sprays. Soil applications are less invasive, less costly, but only last for one season. Trunk injections tend to be more expensive, but will last at least two full seasons.
Soil application of a systemic insecticide for EAB prevention.
Treecology’s Feelings Towards the EAB Situation
There is currently a battle between homeowners, environmentalists, city foresters, arborists, government agencies, chemical manufacturers, and landscapers about the best way to manage Emerald ash borer. The best answer is that there isn’t one. Management plans will vary site to site depending on many factors. Management programs should incorporate both removal and replacement options, as well as chemical treatment options. The impact of trying to conserve our ash trees will cost Minnesotans millions of dollars. However, the economic and environmental impact of doing nothing will be a far greater expense. Unfortunately, there may never be a unified opinion from all involved groups. More focus should be on fighting the insect, instead of each other.
Treecology is a company that was started from the passion of conserving both trees and the environment. As a company, we are not for or against chemical usage. In some cases we will recommend removing and replacing ash trees, while for other situations we will recommend treatment options. In some cases, we may recommend a “wait and see” approach. We have no agenda other than helping our clients make an informed decision about their ash trees. We can provide you the information, our opinions, and our recommendations, but you must make the ultimate decision on what to do with your landscape and your ash trees.