Don't Give EAB a Ride!

Posted by: Denyse Schrenker, Eagle County Extension

People were seeing fireworks last week when it was confirmed that emerald ash borer has made its way to the Western Slope. Two new pockets of emerald ash borer (EAB) in Littleton and Carbondale were recently discovered. These new locations are well outside of the known infested area north of Denver: see Colorado State Forest Service map for known EAB locations. In case you missed it, Emerald Ash Borer is an invasive insect that feeds under the bark of trees during its larval stage. This feeding stops the flow of nutrients and water and gradually kills the tree over a 3 to 5 year timespan. All true ash species (Fraxinus spp.) are hosts for EAB. Green ash (Fraxinus pennsylvanicus) and white ash (Fraxinus americana) are commonly grown in Colorado and both are highly susceptible to emerald ash borer, including their cultivars such as the popular white ash variety, ‘Autumn Purple Ash’. Mountain-ash (Sorbus spp.) are not susceptible to emerald ash borer as they are not a true ash.

Damage from emerald ash borer. Photo credit: Eric R. Day, Virginia Polytechnic Institute and State University, Bugwood.org

How is this different from mountain pine beetles?
Although mountain pine beetle has killed a large number of trees as well, it is a native insect that has periodic outbreaks. The outbreaks are a naturally occurring cycle (though they can be prolonged by human activity) that will eventually end and the surviving trees will regenerate the forest over time. Since emerald ash borer is not native to North America it has no native predators to halt outbreaks so it will continue as long as there are ash trees present.


What Can I Do?

White ash tree. Photo credit: Richard Webb, Bugwood.org

Don’t Move Firewood (remind your friends & family too!)
With camping season in full swing, don’t be tempted to save a couple bucks by taking firewood with you. Always burn firewood locally and buy seasoned and kiln-dried wood as many harmful insects, not just EAB, can hitch a ride in firewood. You can learn more about this at https://www.dontmovefirewood.org/.

Use firewood locally, emerald ash borer and other harmful insects can hitch rides in firewood.

Use Best Tree Care Practices

• Watering Mature Trees
• Watering Your Landscape During a Drought
• Fall and Winter Watering 
• Mulching Trees 
• Healthy Roots, Healthy Trees

Learn to Identify Ash Trees

• Ash Tree Identification
• Contact your local extension office for assistance with identification

White ash leaf. Photo credit: Paul Wray, Iowa State University, Bugwood.org

Learn More about Emerald Ash Borer

• Emerald Ash Borer Resources
• Colorado State Forest Service: Emerald Ash Borer
• FactSheet: Recognizing Wood Boring Insects of Ash Trees in Colorado

Emerald ash borer in exit hole. Photo credit: Debbie Miller, USDA Forest Service, Bugwood.org

Make a Plan

If you are in close proximity to an outbreak, start making a plan for your ash trees. Contact your local extension office for more information.

How Insects Survive Winter

Posted by: Jessica Wong, PhD Student, CSU Department of Bioagricultural Sciences and Pest Management

Insects have remarkable strategies for surviving Colorado winters. A few species migrate to escape the cold. The most well-known species to do this is of course the monarch butterfly. By now they have made their way to roosting sites in Mexico (or California in the case of monarchs from the Western Slope). The green darner, Colorado’s largest dragonfly, is another species that makes its way south before winter arrives. For the rest of the insects that can’t fly thousands of miles, they stay put right here in Colorado.

Migrating green darner dragonfly. Photo by Praveer Sharma, Flickr Creative Commons CC-BY-SA 2.0

Most insects have figured out how to survive our cold, dry, snowy, sometimes balmy winters. A few, like brown marmorated stink bugs and multicolored Asian lady beetles, will escape the cold by going indoors. Cracks and gaps in door and window frames are great opportunities for them, so make sure those are well sealed to prevent them from invading your house. The rest of the insects stay outdoors and go dormant. These insects produce their own antifreeze compounds to withstand temperatures well below 32 degrees. And they have genetic programming that prevent them from coming out of dormancy too early, which is handy on that 70 degree day in February.

Multicolored Asian lady beetles preparing to overwinter. Photo by Howard Russell & Christine DiFonzo, Michigan State University

Insects overwinter in different life stages – egg, larva, pupa, or adult – depending on species. Most species of aphids and crickets survive the winter as eggs. Aphid eggs can be found on trees and shrubs, and cricket eggs can be found in the soil. Japanese beetle and emerald ash borer are two serious pests that overwinter as larvae (also known as grubs). Japanese beetle grubs spend the winter in the soil under turfgrass, such as your lawn. Emerald ash borers overwinter in their galleries just under the bark of ash trees.

Aphid eggs on pine needles. Photo by Beatriz Moisset, bugguide.net

Japanese beetle larvae. Photo by David Shetlar, the Ohio State University

Emerald ash borer larva in its gallery. Photo by Howard Russell, Michigan state University

Black swallowtail butterflies survive the winter in their pupal (chrysalis) form, while another butterfly species, the mourning cloak, overwinters as adults. Bumblebees and yellowjackets also overwinter in the adult stage. Both bumblebees and yellowjackets are social insects with colonies in the spring and summer, but in the fall workers start to die and only fertilized queens survive through the winter. When spring finally comes all the insects break dormancy and resume their unique life cycles. 

Black swallowtail pupa. Photo by Donald Hall, University of Florida

Help Slow the Spread of Emerald Ash Borer

By Carol O'Meara, Boulder County Extension

In the two seasons since detection of the Emerald Ash Borer in Boulder, experts have learned that it’s very difficult to find.  The Colorado EAB Response Team, arborists, and foresters have been looking high and low throughout the Front Range, into tree canopies and on the ground at firewood, trying to find the destructive pest.  For a time, the only place that bug was detected was in the city of Boulder.

But that changed last Monday, June 6, when Bodhi Tree Care Arborist James Young saw the classic symptoms of the Green Menace:  D-shaped exit holes and serpentine galleries just under the bark on an ailing ash tree in Longmont.  He also found one of the bugs half in, half out of the ash, killed as it was emerging from the branch. 

Young notified Ken Wicklund, City of Longmont Forester, who went to inspect the tree.   In the warmth of the day, Emerald Ash Borer adults – half-inch long, metallic green beetles – were flying around the tree.  Wicklund contacted the Colorado Department of Agriculture for confirmation identification, which, sadly, was positive.

At the same time the insect was found in a new Colorado community, our neighbors in Nebraska announced the first detection of the pest, making their state the 26th to have the tree killer.  The speed of the spread – to 26 states since it’s detection in Michigan in 2002, killing hundreds of millions of ash – causes any tree lover to weep in dismay.

As you ponder the decimation of a native North American tree, consider also that complicit in this is humans.  The insect arrived here because humans brought it over from its native Asia.  It was by accident but, like opening Pandora’s Box, the damage was done. 

The insect doesn’t naturally spread more than about 1-and-a-half miles per season; for it to leap across the Great Plains or even across our county took humans, moving it in firewood, nursery stock, or shipping pallets.  Once infested wood arrived, the insects ventured out into surrounding areas, attacking ash trees.  By the time the bug is detected it can be miles away from the original source of the infestation.

This is why Boulder County is quarantined; the EAB Response team is trying to slow the spread.  No firewood or any ash wood can be taken out of the quarantine.  It will take all of us to do this.

Owners of ash trees near or within the detection sites of Boulder and Longmont should make a plan for what they want to do for their ash.  Protection with pesticides, removal, or replacements with saplings of a different type of tree is a personal decision each tree owner should weigh, because the Emerald Ash Borer kills trees in a scant handful of years.  The Boulder County EAB webpage offers information on all aspects of what you need to consider (bouldercounty.org/property/forest/pages/eab.aspx).

To aid in your decision, the Colorado State Forest Service has a Decision Guide that walks you through the process (bouldercounty.org/doc/parks/eab-decision-guide.pdf).   Be sure to assess the health of the ash when considering protecting it; not all trees are healthy enough to save. 

For the most accurate tree health assessment, hire a pro.  Certified Arborists are trained to look for symptoms of EAB and many other pests, be they insects, disease, or environmental problems.  They can climb the tree to take a close look at it.  Find a Certified Arborist through the International Society of Arboriculture (ISA) or look for an accredited company by the Tree Care Industry Association (TCIA).

And don’t move firewood or ash wood around.  This will help slow the spread of the Emerald Ash Borer.

Colorado Multi-Site Woody Plant Trials

Colorado Multi-Site Woody Plant Trials

Dr. James Klett, Eric Hammond, Jane Rozum and Rob McDonald

Colorado State University, Department of Horticulture and Landscape Architecture

and Adams County Extension

Manzano Bigtooth Maple (Acer grandidentatum 'Manzano') Planted in 2013

Colorado can be a tough place to be a plant.  Options for woody plants and particularly tree selection are limited in much of the state due to climate, soils, and disease and insect issues.  Late and early frosts, dry winters with fluctuating temperatures, and calcareous alkaline soils have traditionally limited the diversity of species which can successfully be grown in many parts of the state.  Increasingly limited and expensive water resources coupled with a dry climate also make many mesic species less desirable.  At the same time, many commonly planted species have been affected by serious disease or insect issues such as Dutch elm disease, thousand cankers disease and emerald ash borer.

   

Pests such as emerald ash borer
 are one limiting factor in species selection

In response to this, Colorado State University (CSU) began a multi-site woody plant evaluation program to trial underused and “new” woody plants with the goal of enlarging the size of the plant palate available in the state.  The trial was started in 2002 at five different sites throughout the state.  Since 2002, there have been twelve plantings evaluating a total of sixty-four (64) different taxa.  Trial plants are evaluated based on survival, growth, ornamental appeal, and their potential to be invasive over a five year period.  In 2002, we started with five co-operating sites including three private sector nurseries, Boxelder Creek Nursery (south of Hudson, CO); Harding’s (Calhan); and Little Valley (Brighton) and two CSU research sites, the Horticultural Research Center in Fort Collins (now ARDEC South) and Western Colorado Research Center – Orchard Mesa in Grand Junction.  Originally ten replications of each plant were planted in a randomized block design.   However, in later planting the number of replications was reduced to eight.

The 2015 trial planting at Little Valley Wholesale Nursery

Over the years some of the sites changed.  A major hail storm in 2009 destroyed the planting at Boxelder Creek and that site was lost.  In 2015, we moved the Harding’s Nursery site to the Colorado Agricultural Leadership Foundation near Castle Rock, CO.  Planting continues yearly. In 2015 we planted five taxa and in 2016 plan to plant another five taxa.  We continue to take growth and performance data on woody plants to determine if any merit introduction into Colorado and Rocky Mountain Landscapes with the Plant Select® designation.

Dr. Jim Klett taking data on the 2011 planting

Woodward Juniper (Juniperus scopulorum 'Woodward') a 2015 Plantselect® 

selection and part of the 2006 trial planting

Some of these woody plants have been recommended or introduced through the Plant Select® program including Acer tataricum ‘GarAnn’^PP15023 (Hotwings® Tatarian Maple); Arctostaphylos x coloradoensis (Mock Bearberry Manzanita); Arctostaphylos x coloradoensis (Panchito Manzanita); Heptacodium miconioides (Seven-son Flower) and Juniperus scopulorum ‘Woodward’ (Woodward Juniper).  I plan to highlight these and other plants which have stood out in the trials in future posts.

The 2006 plant at Harding's Nursery during the summer of 2014

Support for this project comes from Colorado Horticulture Research and Education Foundation, Plant Select®, Colorado State University Agricultural Experiment Station, and cooperating nurseries mentioned above.

Assessing Ash risk

Posted by: Carol O'Meara, Boulder County Extension

In the months following the detection of Emerald Ash Borer in Boulder, people have been holding their breath, waiting for word on where the pest would show its presence next. They’re gazing at their ashes, appreciating what they have that might, in a short time, be gone.

Advertisements by mail or on the radio make the situation seem dire (one announcer sounds as though he’s shaking with rage that the insect dared come to Colorado). If you’re wracked with indecision on what to do to protect your ash or when to do it, take a deep breath and relax before making your decision.

Distance from the detected pest is the first question to answer; in Colorado CSU Entomologists recommend that only those ashes within five miles of the bug need protection. If you live further away than five miles from the pest, you have time to plan before booking tree treatments.

Check how close you are to the five mile zone by clicking on the Ash Tree Management Zone Map. There, you can type in your address and the map will zoom in to your location and identify the risk zone you live within.

Then build a plan, starting with an assessment of your trees and whether they’re healthy. Not all ashes are healthy enough for treatment; should they have greater than 40-percent dieback of their canopy they won’t translocate treatments effectively through the tree. Small trees could be protected, but ask yourself if it would be better to remove and replace them with another tree type. Often, costs of treatment far outweigh the costs of replacement.

Next, assess the type of treatment you would like for the tree. Small trees of less than 15-inch diameter can be helped with products you can purchase and apply yourself. But be careful – these products contain pesticides harmful to bees, so make sure there are no blooming plants, wanted or unwanted, in the ground under the tree (especially dandelions).

If your tree is larger than 15-inches or you’d like options that are more bee-friendly, ask your tree care company to help you in your decision. Don’t be alarmed by radio ads – heavy with reverb – announcing the presence of the pest. Arm yourself with the facts by going to eabcolorado.com and scroll down to How to Manage EAB and click on control options for information on the available treatments.

Ode to EAB Peeling

By: Alison O’Connor and Tony Koski, CSU Extension

'Twas a cold day in December, and outside the shop,
Were piles of ash branches with emerald ash borer to stop.

The draw knives were lined up on the bench with care,
In hopes that many volunteers soon would be there.

Ash branches from the delimitation survey waiting to be peeled.

The larvae are snuggled down in the logs,
Waiting for spring to emerge and attack like dogs.
The feds and the state will determine their fate,
Hopefully prior to the beetles finding a mate.

EAB was found in an ash in September,
Which Kathleen Alexander quickly came to dismember.
All in the midst of disaster and flood,
Another insect in Boulder--Oh crud.

The City of Boulder was divided into 39 squares,
In each 10 trees were sampled to find EAB lairs.
Two branches per tree of just the right girth,
To find one of the most destructive beetles on earth.

The point of peeling is to remove all the bark,
Because on the outside there is rarely a mark.
A sign under the wood of this terrible green beast,
Are the S-shaped galleries where the larvae feast.

 

Removing all the bark from an ash branch.

We peel hoping to find the creamy white worms,
When you find one, they tend to wiggle and squirm.
The goal is to remove them completely intact,
The larvae may be sent to Washington D.C., in fact.

Wafer-thin layers are peeled with care,
Straight down to the cambium with nary a tear.
It’s a tedious, yet satisfying kind of work,
Especially with good music and the occasional twerk.

 

Wafer-thin slices of wood are removed carefully.

 There’s an easy camaraderie among all who peel,
Slowing the movement of EAB is a big deal.
Our hopes are the survey will tell us where it has spread,
To prevent more ash trees from becoming dead.

So that's what we do in the Boulder Forestry shed all day,
We toil away gladly without additional pay.
We feel a little like elves making toys,
Except our end result is preventing EAB joy.

 

The "bone pile" of peeled branches.

To everyone who lifts a draw knife to volunteer,
We wish you a holiday season full of good cheer!

 

Happy Holidays from your CSU Horties and the EAB Yule Tree!

"Promise America" to Not Move Firewood!

Alexis Alvey, Horticulture Agent, CSU Denver Extension

What do baseball bats, bugs, and ash trees all have in common? (And no, this is not some lame, bar room joke.)  Well, they are all part of the "Promise America" campaign initiated by the US Department of Agriculture.  This campaign has been launched to educate everyday homeowners and gardening enthusiasts alike about the invasive insect pest called the Emerald Ash Borer (Agrilus planipennis) which is killing literally millions of ash trees across America.  There are a handful of different species of ash trees that are native to the Midwest and the East Coast that are commonly planted as great urban street trees throughout the US, including Denver.  Wood from ash trees has traditionally been used to make baseball bats.  Unfortunately, all of our native ash, including White Ash (Fraxinus americana) and Green Ash (Fraxinus pennsylvanica), which are the two species planted in horticulture, are completely at the mercy of Emerald Ash Borer.    This tree-killing beetle was first identified in the US in 2002 near Detroit, Michigan and is native to eastern Russia, northern China, Japan, and Korea.  No one knows for sure how or when it got here, but most likely in the 1990s it came to the US in ash wood used for stabilizing cargo in ships or for packing or crating heavy consumer products.  It has now spread into seventeen additional states and two Canadian provinces and continues expanding its range.  Its spread has been accelerated by the movement of infested firewood.  Last year it was discovered in Kansas for the first time, and people are worried that it will soon be in Colorado.  Denver Parks & Recreation’s Forestry Division will begin monitoring for Emerald Ash Borer for the first time this season. 

Photo: Adult Emerald Ash Borer 

(Leah Bauer, USDA Forest Service Northern Research Station, Bugwood.org)

The Emerald Ash Borer is actually a relatively pretty insect (I say relative, because in my opinion all insects are kind-of gross.)  The adult beetles are a bright, metallic green, a half-inch long, and have a flattened back. But the problem is not the adult beetles, it is their larvae.  The larvae are a type of flatheaded borer.  (By the way, “You are such a flathead!!” makes for a great insult!)  Larvae hatch from eggs laid within bark crevices and under bark scales in the spring.  They chew through the outer bark of the tree and into the cambium where they feed in the phloem interrupting the flow of nutrients within the tree, ultimately girdling it. 

Signs and symptoms of Emerald Ash Borer infestation are yellowing leaves on branches and then dieback generally in the top of the tree canopy first.  Sprouting from the base of the trunk can also occur.  If you are lucky and look very very carefully, you may see small holes in the trunk that are 1/8” in diameter and that are D-shaped.  Complete defoliation and tree death typically occurs within 2-3 years.   

Photo: Green Ash dead due to Emerald Ash Borer 

(David Cappaert, Michigan State University, Bugwood.org)

Unfortunately there is no simple cure for Emerald Ash Borer.  This little beetle has had an enormous economic and ecological impact.  The devastation of the insect is remarkable - over 53 million ash trees have died or are dying from the borer and all of North America's 7 billion ash trees are at risk.  It is estimated that up to $26 billion has been lost due to the borer in just four Midwestern states.  This took into account the cost of lost tree value, tree removal, and tree replacement. 

Invasive pests have been incredibly problematic for our urban trees and native forests for the past century.  From Dutch Elm Disease to Chestnut Blight to Asian Longhorn Beetle, invasive insects and disease have changed the composition and ecological functioning of our forests as well as their look and feel.  So please, “Promise America” that you will not move firewood; that you will burn firewood where you buy it; and that you will plant a diverse selection of trees and not all the same species. Oh, and that old wooden baseball bat of yours may be more valuable than you think!  

Photo: http://stopthebeetle.info/

For more information, visit:

www.emeraldashborer.info

stopthebeetle.info

www.dontmovefirewood.org