Emerald ash borer (EAB) is a beetle native to Asia and it is a serious concern for our ash trees all over North America. EAB adults lay their eggs in the cracks of the bark in ash trees. These eggs hatch and the larvae then tunnel into the cambium - eating the trees vascular tissue. The eating of the vascular tissue forms what are called galleries in the bark, which do not allow nutrients to properly circulate in the tree, This causes decline and death in affected branches and eventually the whole tree will be killed.

In terms of pests that destroy large populations of trees EAB is unique. Almost all of the others (Dutch elm disease, blue stain fungus, and thousand cankers of black walnut) cause damage through a fungus and a bark beetle which spreads the fungal disease, like malaria is to mosquitos. These relationships require both the vector and the pathogen for the disease to spread and allows for control of one or the other to effectively slow the spread. EAB is different as there is no vector pathogen relationship and the beetles can destroy trees all on their own. These beetles have no natural predators in North America and chemical controls of the beetle are quite costly. 

Yes. Some tree pests only target trees that are already stressed but EAB has the unusual ability to attack and very quickly kill completely healthy trees. The alarming thing about EAB is that it can cause irreversible damage in just one to two years.

EAB is already considered the most destructive pest for the forests of North America. (second only to humans) EAB kills every untreated ash in its path and has already killed hundreds of millions of trees in the US. This is such a concern in Colorado because ash trees are one of the @few trees that grow well in our urban landscape. The city of Denver estimates that one in five trees planted in the city are ashes and the rest of the urban forest in Colorado likely has a similar percentage.

All of Boulder county except Louisville has been affected by the beetles as of 2018. All true ash trees (genus Fraxinus) are susceptible to attack. Mountain ash (genus Sorbs) are not true ashes and are not at risk to EAB.

Control of the beetles is primarily done in one of two ways. There is a @neonictinoid called imidicloprid which is applied by drenching the soil around the base of the tree and it must be done every year. This is the least desirable of the methods for a few reasons. Neonictinoids are toxic to bees and the application method of pouring toxic chemicals into the ground has the potential to be absorbed into other non target plants potentially causing flowers to become toxic to bees and other non target insects or animals. There is also serious potential for runoff which leads to the chemical spreading into lakes and streams where the effects can be harmful to the plants and animals that live there. The second method of treatment is with emmamectin benzoate. This is a chemical derived from a natural soil bacteria. The application method of this is through direct trunk injection. We use the Tree I.V. system which keeps the chemical contained completely in the tree without risking contact with non target organisms. Ash trees are pollinated by wind sothere is no chance for bees being harmed by visiting the flowers of a treated tree. The chemical also treats the tree for two years so treatment does not need to be done as often. 

The major drawback is that the tree must be drilled with small holes during treatment and any time you are poking holes in a tree it has the potential for negative consequences. Although there are drawbacks to the tree I.V. method we refuse to use any other method because of the non eco-friendly nature of the products. 

Studies have shown the treatments are essentially completely effective when used as a prophylactic on uninfected trees. The issue with trying to treat after there is noticeable damage is that the trees vascular system is compromised and @translocation of the chemical will be less effective. Trees that have been damaged can sometimes be saved but sparse canopies cause by initial infestation will take many years to reverse and many people choose to remove the tree rather than having to stare at an unsightly tree everyday. 

In general EAB will only fly a half mile or more to find a new host. The primary spread is most likely caused by irresponsible movement of ash wood by people who take the wood for burning and irresponsible tree companies who disregard proper regulations regarding disposal of the wood.

The tips will begin to have more sparse foliage and large dead tops. The tree will respond to the loss of this foliage by activating dormant buds under the bark and sprouting new shoots down the main stem causing a bushy appearance. (The photo at the top of this page is an ash in the late stages of decline)

That is a question you must answer for yourself, but trees that are in good condition and add to your outdoor landscape are great candidates for protection. Trees that are in poor shape may not be worth keeping although some people still choose to retain them as treatment is always less expensive than removal and replanting of a new tree. The decision is your to make but any untreadted trees will die and the treatments are essentially completely effecteive when used as a prophylactic.

The equipment involved and the chemicals are quite expensive so unfortunately treatments are as well. Extensive training is required to ensure that treatment is done properly. We are also required to have state licenses for all applicators and the company is required to be licensed through the state. Our price for treatment is $12 per inch of diameter at breast height. (54 inches above ground)

Just give us a call, text or email and set up a consultation with our Board Certified Master Arborist and we can help you with any concerns you may have.