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Denver’s Ash Trees Ready for Second Treatment

If you were out and about in Denver in 2016, you likely saw hundreds of ash trees wrapped in plastic that said, “Be A Smart Ash.” Denver Parks & Recreation’s Office of the City Forester treated public right-of-way ash trees adjacent to private properties throughout the city to prevent an Emerald Ash Borer (EAB) infestation. Although the treatment of ash trees by a tree care professional is 90% effective, treatment must be repeated every two to three years to remain successful. With this in mind, we will be treating these trees again.

Healthy ash trees that are 12 inches and larger in diameter at four feet off the ground were put on a list for potential treatment. From this list, a number of trees were randomly selected in each neighborhood to be treated in either 2016, 2017 or 2018.  Because trees require treatment every two to three years, we’re revisiting the 2016 trees now. Every ash tree scheduled to be treated was examined by a city arboreal inspector to determine if it was a good candidate for treatment.

EAB is a destructive pest that kills ash trees and poses safety and financial risks. However, this treatment, when done in advance, is more than 90% effective in preventing tree death.

photo courtesy of @watersa on Instagram

Risks of avoiding treatment Include:

  • Ash trees killed by EAB become very brittle and can break easily. Dead ash trees are dangerous to you and your neighbors and can be expensive to remove.
  • You are responsible for removing infested or dead EAB trees on and adjacent to your property, so treat your tree!
  • EAB has the potential to destroy Metro Denver’s 1.45 million ash trees – roughly 1/6 of Denver’s trees – significantly impacting our precious tree canopy.

Trees are critical for our overall quality of life. They produce oxygen, reduce smog, cool our neighborhoods and homes and increase our property values. Join our effort to save Denver’s ash trees by talking to your neighbors, friends and co-workers about EAB and encourage people to visit BeASmartAsh.org for more information. To see which ash trees are being treated and those that are candidates for future treatment, visit BeASmartAsh.org/treatment-schedule.

Removing and Replacing Your Ash Tree

One of the four recommended treatment options for a tree infected with emerald ash borer (EAB) is to remove the tree and replace it with another species that can grow well in Colorado. Though the EAB has yet to be found and confirmed in the Denver Metro Area, the removal and replacement option is both cost-effective and convenient for homeowners.

Step one is removal of the ash tree and step two is replacement. While it sounds easy enough, hiring a tree professional will make this process significantly easier. There are many tree professionals that are licensed by the Office of the City Forester who can lend a hand.

We connected with the wise folks at Denver Parks & Rec to ask for their recommendations for tree replacements. We asked for suggestions for species that will easily thrive in our local climate when provided adequate care. Drumroll, please…

Smaller Trees | Less than 30-feet high

Amur Maackia – photo courtesy of Oakland Nurseries
Any redbud – photo courtesy of Arbor Day Foundation
John Pair maple – photo courtesy of Iowa City Landscaping
Peking lilac – photo courtesy of Forestfarm
Three-flower maple – photo courtesy of Heritage Seedlings

Shade Trees | 30-feet and taller

Espresso Kentucky coffeetree (without seeds) – photo courtesy of Your Garden Sanctuary
Prairie expedition elm – photo courtesy of Laidback Gardener
Tuliptree – photo courtesy of Tennessee Wholesale Nursery

Trees in the approved list are those which, given proper and consistent maintenance including supplemental irrigation, proper pruning, and avoidance of chemical contaminants, will be assets to Denver’s beautiful urban canopy. You can also explore the approved list in its entirety.

Denver Botanic Gardens Spring Plant Sale


Spring has sprung and Denver residents are preparing their gardens for the summer months ahead. While we’re certain you have flowers on the mind, your trees deserve your love and attention too! The Be a Smart Ash team will be on-site next month at the Denver Botanic Gardens Spring Plant Sale to discuss all your questions about ash trees. Ask us about our ruthless plan to foil the invasive Emerald Ash Borer (EAB) and take a selfie with the fearless and rugged Smart Ash.

The city of Denver manages the ash tree population in public spaces and in the right-of-way, but any ash trees on your property are your responsibility. The fight against EAB is real as it’s only a matter of time until they are found in our beautiful city. You can have a tree care professional treat your tree or remove and replace it with one of these City Forester-approved trees (some of which you might be able to get for free). With your help, we can maintain the long-term stability of our urban canopy.

The event details are below. As always, you can follow us on Twitter at @BeASmartAsh in the meantime. We look forward to seeing you!

What: Denver Botanic Gardens Spring Plant Sale
When: Saturday, May 11 from 8 a.m. to 5 p.m.
Where: 1007 York Street, Denver, CO 80206
Cost: Admission is free and prices vary for plants – both cash and credit cards are accepted
Bring: A cart, wheelbarrow or wagon to haul your treasure
Enjoy: Complimentary valet to load your purchases directly into your car
Sneak peek: Over-achievers who want a sneak preview of the plants available for sale on Saturday can attend a ticketed event on Thursday, May 9 from 4 to 8 p.m. at the gardens. Tickets sell out quickly and cost $45. You’ll have access to expert horticulturists, appetizers, wine, beer and plants.
Questions? 720-865-3500

Be A Smart Ash & Denveright

Here at Be A Smart Ash, it’s our job to create a defense plan that protects Denver’s 330,000 ash trees from emerald ash borer (EAB), the most destructive forest pest in U.S. history. It has already caused a billion dollars’ worth of damage in more than 30 states and parts of Canada.

But our job goes much deeper than that.

The Be A Smart Ash movement is one part of the much larger process that we know as Denveright, an unprecedented opportunity to align citywide plans to guide future investments so that the whole is greater than the sum of its parts.

Thousands of Denverites shared their unique perspectives on what makes Denver great and how it can evolve to improve even more. You shared your voice in many ways — by attending meetings and workshops; taking online map-based surveys; talking with the Denveright street team at festivals, community events and transit stations; joining a Community Think Tank; and more.

As it relates to our parks, recreation and urban forest, you made it clear: You view these places as vital components of a complete community. And it’s our job at the Office of the City Forester to deliver them for you.

Enter the Game Plan for a Healthy City and Blueprint Denver.

Game Plan for a Healthy City

This is a new citywide parks and recreation plan for the next 20 years that proclaims easy access to parks and open space is a basic right for all residents. The Game Plan provides a roadmap for supporting and building our parks, recreation programs and urban forest to serve the needs of all Denverites in the face of ongoing population growth and climate change.

So what challenges are we facing that the Game Plan addresses? There are six big ones:

  • Drought & Flooding: Roughly 11%, or $2.7 million, of our annual parks operating budget goes toward irrigation. The less drought-tolerant landscape could be lost. Droughts and flooding are both projected to increase in the future.
  • Parks Not Keeping up With Growth: From 2010-2016, the city experienced 11% growth while park space grew at a slower rate. Denver’s park inventory of nine acres per thousand residents is well below the national average of 13 acres per thousand residents.
  • Growth Economic Challenges: Deferred maintenance totals are $119 million and nearly one in six park assets are in poor condition. Expenses have significantly outpacing funding growth.
  • Limited Access to Nature: Many neighborhoods lack walking access to places where they can experience nature. Mountain parks are difficult to access for families without a car.
  • Obesity is Rising: Nearly one in six children is obese and 52% of Denver’s residential parcels are not within a 10-minute walk of a playground.
  • Threatened Urban Forest: Last but not least, Denver’s urban tree canopy is one of the lowest in ranked cities and one in six trees are threatened by EAB.

Are these big challenges? You bet. But as we like to say around here, who wants to be a Debbie Downer when you can Be A Smart Ash? We have a 20-step plan for the next 20 years to address each and every one of these issues. Each one falls under one of four Game Plan principles: 

  • Every Drop: Adapt to the changing climate and limited resources to make the parks system more resilient and environmentally sustainable.
  • Every Person: Ensure equity in the distribution of parks and park resources and programming so that all residents have the opportunity to improve their personal health and well-being.
  • Every Dollar: Manage resources to ensure long-term economic and operational health of the parks system.
  • Uniquely Denver: Provide parks and programming that reflect Denver’s community and cultural identity.

As it relates to our urban forest, our goals are even more specific and there are ways you can help!

Blueprint Denver

Working in conjunction with the Game Plan, Blueprint Denver is a citywide land use and transportation plan for the next 20 years that calls for growing an inclusive city through three basic ideals:

  • Complete Neighborhoods: Creating complete neighborhoods and complete networks everywhere in our city, to meet the needs of all Denverites.
  • Growth Strategy: A measured, common-sense approach to where growth should take place and how it should fit in.
  • Equity: For the first time, considering social equity factors so we can tailor solutions to each neighborhood’s unique needs — ensuring changes will benefit everyone.

Once again, lofty goals, right? Well, we have another 20-year plan that we believe will get us there, with these elements at its heart:

  • Land Use & Build Form: Continue to build the character and quality of places in neighborhoods.
  • Mobility: Connect people to the neighborhood places where they live, work and play.
  • Quality-of-Life Infrastructure: Provide neighborhoods with natural features, active recreation opportunities and social spaces.

At City Forestry, we’re particularly passionate about Quality-of-Life Infrastructure, and we’ve got specific plans to develop and strengthen it. And once again, you can help!

Long story short, Denver has big goals. With your help, the Denveright process will lead us down a path to accomplishing each and every one of them.

Emerald ash borer discovered in Lincoln, Neb.

LINCOLN, Neb. — Emerald ash borer (EAB) was first found in Nebraska in June 2016, but it has now been discovered in Lincoln, the state’s second largest city. The news was confirmed by the Nebraska Department of Agriculture (NDA) in partnership with the U.S. Department of Agriculture (USDA) on Aug. 22.

Previously, the NDA had confirmed infestations in Cass and Douglas counties. Douglas County is where Omaha, Nebraska’s largest city, is located. In addition to the discovery in Lincoln, the NDA also reported signs of an infested tree in the smaller town of Fremont, which is approximately 50 miles north of Lincoln.

“While it’s unfortunate we found EAB in Lincoln and signs of an infested tree in Fremont, it is not unexpected considering we have confirmed EAB infestations in Douglas and Cass counties,” NDA Director Steve Wellman said.

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Traps set to determine if & when emerald ash borer reaches Denver

DENVER — If you’re wandering through one of Denver’s public parks this summer and find yourself looking up to admire one of the city’s historic ash trees, you might notice a green or purple object hanging from it.

So what the heck are these things?

They’re known as sticky traps, and the Denver Parks and Recreation’s Office of the City Forester has deployed them in strategic parts of the city in an effort to determine whether the emerald ash borer (EAB) has arrived in the Metro area.

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Boulder Creek, EAB, infested, ash tree, emerald ash borer

172 EAB-infested ash trees to be removed along Boulder Creek

BOULDER, Colo. — One of the most iconic paths in Boulder, Colo. is about to lose one of its greatest features: a vast amount of the trees that shade it from the summer sun.

The City of Boulder Forestry Division announced in June that it would be removing 172 trees along the Boulder Creek Path beginning June 18 and continuing through September. The trees slated to be removed are ash trees that are either dead or dying after having been infested by emerald ash borer (EAB), the most destructive forest pest in U.S. history.

The majority of the ash trees scheduled to be removed along the Boulder Creek Path are under seven inches in diameter, and are located between the 9th and 30th streets. The path itself is about five miles long, and the area where the trees will be removed represents nearly a two-mile stretch of it.

The primary reason for the tree removal, according to the City of Boulder Forestry Division, is to mitigate safety issues caused by the potential for falling limbs from dead and dying ash trees affected by EAB. This move comes just a year after 121 trees were removed from the University of Colorado campus in Boulder for the same reason.

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EAB in Colorado, threatening ash trees

Emerald Ash Borer Detected in Superior, Colo.

SUPERIOR, Colo. – State officials have confirmed the presence of emerald ash borer (EAB), an invasive, highly destructive tree pest, in the Town of Superior in southeast Boulder County. This new detection is still just within a quarantine area established to try and prevent the human-assisted spread of EAB. However, it represents the fifth community with confirmation of EAB in Colorado outside the City of Boulder, where the pest was first detected in 2013.

An estimated 15 percent or more of all urban and community trees in Colorado are ash species susceptible to being killed by EAB – and a majority of these trees are on private land. There are 1.45 million ash trees in Metro Denver, and in the City and County of Denver specifically, one in six trees trees is an ash.

EAB attacks and kills both stressed and healthy ash trees and is so aggressive that trees typically die within two to four years after becoming infested. Additionally, it may be years before an ash tree shows signs of infestation, and by then it may be too late to save. That’s why the Denver City Forester is recommending the preemptive treatment of ash trees in the metro area.

The pest was confirmed in Boulder this week, shortly after Boulder County foresters identified a dead adult EAB on a trap the county had set – along with a dozen others in targeted areas – to detect for early infestation of the pest. This particular trap was located on public property along the Mayhoffer Singletree Trail, near the intersection of West Thomas and Third Avenue in Superior.

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All Eyes On Me: Emerald Ash Borer Emergence

DENVER — It is already June, which means we are at the start of Emerald Ash Borer (EAB) emergence season! Although EAB has not yet been found in the City and County of Denver, we know it is only a matter of time before its discovery.

EAB emergence season means it is time to start looking for the adult borers who leave “D”-shaped holes in the bark of the ash tree, roughly 1/8 inch in diameter. There are also several other telltale signs of EAB infestation like S-shaped tunnels that can be seen on the trunk and tree thinning and bark shedding. Dying ash trees also attract Northern Flickers, a type of large, brown woodpecker. It can take 2-4 years for trees to show signs of infestation.

EAB chews through the tree’s water and nutrient-conducting tissues, strangling the tree. If there is a high population of EAB in the tree, one-third to a half of the branches may die in one year. Most of the canopy will be dead within 2 years of when symptoms are first seen.

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The Smart Ash Explains EAB Treatment Options

Be A Smart Ash has been turning Denver residents into smarter tree owners since 2016. And while emerald ash borer (EAB) hasn’t yet been found in Denver, we know it’s just a matter of time. But even if Denverites know if they have an ash tree in their yard, they still may need more details about treatment options.

While ash tree treatment seems like a straightforward topic, it can be surprisingly complex. In fact, it combines a good bit of chemistry, can depend on how you feel about your tree, involves some budgeting, and the options can be difficult to demonstrate. In short – ash tree treatment is anything but straightforward.

Enter The Smart Ash. Voiced by our very own Denver City Forester Rob Davis, and inspired by the popular PBS Kids show Wild Kratts, The Smart Ash is a character on a quest to defeat EAB and defend the ash trees that make up Denver’s invaluable urban forest. The campaign is designed to be entertaining but informative – especially when it comes to emphasizing safety and the value of working with a tree care professional to treat or remove trees.

So, join The Smart Ash as he breaks down the various ash tree treatment options into a handful of short videos. Whether you’re searching for a specific treatment option or want to peruse the variety that are available, The Smart Ash has you covered.