Tuesday, October 22, 2013

Are Your Ash Trees At Risk?

Alexis Alvey, Horticulture Agent, CSU Denver Extension

Imagine if every tree on your street had to be cut down.  Would it still feel like home?  Would it still feel like your neighborhood?  Would you be prepared to pay for extra air-conditioning and heat?  Would you be prepared when the value of your home decreased?  This has actually happened in numerous communities throughout the country where streets lined with Ash trees have been decimated by an invasive insect pest called Emerald Ash Borer.  At the end of September, this lethal insect was discovered in Colorado for the first time in Boulder.

How many ash trees do you see in this photo from University Blvd. in Denver?

Invasive insect pests and new fatal tree diseases are seriously impacting our nation’s forests, our community’s street trees, and our own backyards.  Over the past century, global trade has greatly expanded and has inadvertently facilitated the introduction of invasive pests into this country through various means including wood packing materials.  Insect pests and diseases that are native to other areas of the world are able to cause an alarming amount of damage to our trees.  Because our trees did not evolve with these new insects or diseases, they did not develop a natural defense mechanism and succumb easily.  Our native trees have died by the millions due to diseases like Dutch Elm Disease and pests like Emerald Ash Borer.  It is estimated that over 53 million ash trees have died or are dying due to Emerald Ash Borer.

Currently, plans are underway to assess the extent of the infestation of Emerald Ash Borer in Boulder.  You can be sure that other municipal forestry departments throughout the Front Range are going to ramp-up their efforts to survey for this insect.  We will let you know about the status of Emerald Ash Borer as new information becomes available.  In the meantime, I would encourage everyone with an ash tree in his or her yard to educate him or herself about this lethal insect.  For national information, visit: and for Colorado-based information, visit:

Ad from the national campaign to slow the spread of Emerald Ash Borer

Also, please be sure to not move firewood – this is one of the main pathways that Emerald Ash Borer has spread around the country, beginning new infestations at campsites.  Make sure that your firewood is heat-treated (which kills any larvae developing in the wood) before you transport it, or that you simply buy firewood where you are going to burn it.

If you think you have Emerald Ash Borer in your ash trees, or if you have any questions or concerns, or would like additional information, please contact the Colorado Department of Agriculture at 888-248-5535 or email

The culprit - Emerald Ash Borer
Photo source: David Cappaert, Michigan State University,


  1. Great blog, Alexis...timely information and good advice!

  2. Good and informative post about Ash trees. And thanks for sharing the further links where we can learn more about the safety for these productive plants. If we love our environment, we have to step up and save them for the future.