10 FAQ’s for Emerald Ash Borer Planning

After its discovery in 2002 in Michigan, Emerald ash borer (EAB) has killed millions of ash trees in a short time period.  The Emerald ash borer is an exotic insect pest (non-native), so ash trees have no natural protection methods to fight off the insect. Unfortunately, EAB was found in Minnesota in 2009 and has already started to change our landscape.  Most effective EAB management plans will involve a combination of efforts including removal of ash trees, replacement of some ash trees, as well as treatment options to save valuable ash trees. 

The damage from Emerald ash borer can go unnoticed for 2-4 years before a tree declines and eventually dies.  Since prevention is the most effective management practice, a plan should be in place as soon as possible.

10 Frequently Asked Questions

1.   What will the impact be financially for EAB in Minnesota?

Regardless of your management plan decisions, the Emerald ash borer is going to be costly for everyone.

2.    Can ash trees survive without chemical treatment?

Untreated ash trees have virtually ZERO chance of survival.

3.    Should I keep and treat my ash trees?

Not all ash trees should be kept and treated.  Ash trees must be healthy, have good structure, have a good growing location and should be a significant size in order to be considered for treatment.

4.   Can smaller trees be kept and treated?

Any ash tree smaller than 10 inches in diameter should NOT be chemically treated.  The value of replacing smaller trees is much higher than chemical treatment for many years. 

5.  Can unhealthy trees be treated?

Unhealthy trees should be removed, unless the health can be recovered.  Healthy trees have a higher chance of survival.

6.  If an ash tree has questionable structure what should be done?

Ash trees with poor structure should be removed, unless the structure can be corrected with pruning.

7.    Are chemical treatments effective?

Chemical treatments are effective but must be used preventively and continually.

8.   Which chemicals are effective?

Emamectin benzoate is the most effective chemical and must be applied every 2 years via trunk injections.

9.    Why are there so many different opinions on EAB planning?

Opinions on the EAB planning may differ greatly because of different interests from parties involved (municipalities, environmental groups, arborist, chemical distributors, equipment manufacturers, nurseries).  Each of these parties can benefit directly or indirectly depending on decisions made.

10.  Should I just wait and see what happens?

Doing nothing is the costliest decision because all untreated ash trees will be dead and will need to be removed. 

An EAB-infested ash tree being removed before damage worsens.

The Bonus Question = How long do I have to treat my ash trees?

Unfortunately, there is no exact answer for this question. In Minnesota, the EAB invasion has been slower than other states. Our colder winters have helped a bit, plus we knew EAB was coming well in advance. We started removing unhealthy and undesirable ash trees and started treatments well in advance.

Note from The BIG Oak = When making a decision to keep and treat ash trees (or remove them), just assume that treatment will go on for the life of the trees. It is possible that at some point every ash tree will either be dead or chemically treated (the EAB Death Curve). It was proposed this would happen in 12 years. For Minnesota at least, I think you can throw this theory out and plan treatment for the long haul.