Main Street® Shantung Maple Acer truncatum ‘WF-AT1’

James Barborinas James Barborinas
Urban Forestry Services, Inc. & Urban Forest Nursery, Inc.
Learn more about James Barborinas.

Have you heard of the Main Street® Shangtung maple, (Acer truncatum, ‘WF-AT1’)? I hesitate to explore another maple as most cities are trying to find alternates to avoid over planting them. However, more selections and cultivars keep emerging and they certainly are a proven genus and a favorite throughout the country. The Main Street® maple is a recent selection with favorable urban characteristics introduced by Worthington Farms of Greenville, North Carolina.  Given our ever-shrinking sites for urban tree planting, this smaller scale tree is one to consider.

An interesting comparison is that the Main Street® maple is very much like a smaller version of the Pacific Sunset, (Acer truncatum x A. platanoides ‘Warrenred’) or Norwegian Sunset, (Acer truncatum x A. platanoides ‘Keithsform’) maples, which easily and quickly reach 35 to 40 feet tall and wide. Note: I have personally seen Pacific Sunset maples get wider than they are tall. This assessment of the Main Street maple would include the leaves, twigs, branching and ultimate height and width, all being less in size. Read More "Main Street® Shantung Maple Acer truncatum ‘WF-AT1’"

Early PNW-ISA Chapter Arborist Certification

John Hushagen
Retired Commercial Arborist - PNW-ISA CoR Delegate
Learn more about John Hushagen.

Most current members in our region are likely unaware that before there was a Certified Arborist exam sponsored by the International ISA, the PNW chapter had its own CA (Certified Arborist) test. In the late 1980’s, the Western chapter had developed an immediately successful certification exam for its region.  Some of our chapter founders promoted making arborist certification available to PNW members. Around this same time, Susan Murray, a chapter member and college horticulture instructor from the Vancouver, BC area wrote an arborist certification as part of her Master’s thesis.

In 1990 or early 1991, a small committee of chapter members from BC, Washington and Oregon, began to meet to go through Susan’s exam, question by question, and make it ready for PNW members to take.  This process took several months, and I believe we had the exam ready to present at the ATC in the fall of 1991. Not to be outdone by the upstarts from the West Coast, within 12-18 months, the International ISA had its own exam ready to deliver, and it replaced all individual chapter tests.  All those who had passed the PNW exam had their CA status recognized by the International. Certification fueled the rapid growth of the PNW chapter and the whole ISA, and helped turn even spur climbing toppers into real arborists all around the world!

Updates from the Board of Directors

Phil Bennett Phil Bennett
Learn more about Phil Bennett.

Transition Update

In February 2019, the Board of Directors reviewed the results of an Organizational Assessment completed by Loveall Price & Associates, a nonprofit transitional consulting firm. The Board accepted the recommendations in the assessment, including initiatives to update operational systems, and move towards a virtual office for the Chapter. Staff have been working diligently to implement those recommendations.

PNW-ISA has retained Loveall Price and Associates to assist with an Executive Director Search that will commence later this summer.  We will hire a new executive Director for the Chapter by the end of 2019.

PNW-ISA Board of Directors Positions Available

If you are interested in serving on the PNW-ISA Board of Directors, please complete the Board interest form.  A Board Position may be available prior to this year’s Annual Training Conference (ATC), and elections will be held for several positions at ATC.

TREE Fund Summer Update

Evan Sussman Evan Sussman
Board Liaison to the TREE Fund
Learn more about Evan Sussman.

Greetings arborists! I wanted to write a brief update on the on goings at the TREE Fund. For anyone who isn’t familiar with the TREE Fund, they manage endowment funds that support research and education for arboriculture. A lot of the current and past research that we base our practices on has been funding in part or whole by the TREE Fund.


Webinars are in full swing. These are a great way to stay in the loop with current TREE Fund researcher’s works, and to get free CEUs. Upcoming this year are:

Remediating Compacted Soils Compromised by Urban Construction
Dr. Nina Bassuk, Cornell University
June 11, 2019, 11:00 am PST

Can We Vaccinate Trees to Protect Against Diseases?
Dr. Glynn Percival, Bartlett Tree Experts Research Laboratory, UK
August 29, 2019, 10:00 am PST

Health Benefits of City Trees: Research Evidence & Economic Values
Dr. Kathleen Wolf, University of Washington
November 19, 2019, 11:00 am PST

All of these webinars are good for 1 free CEU!  You can access the archive of previous webinars at Additionally, you can stay up to date on future webinar offerings at that link or by following our PNW-ISA Facebook page.

Read More "TREE Fund Summer Update"

Check Out Our Tree Climbing Workshops This Summer!

Melissa Amrhein
PNW-ISA Education Program Manager
Learn more about Melissa Amrhein.

Philip Kelley and Jamilee Kempton, August's workshop instructors

We hear you! When members share their education requests in our annual member survey and workshop evaluations, PNW-ISA identifies how we can meet your needs. Members repeatedly ask that the Chapter offer more tree climbing workshops and we responded!

This summer PNW-ISA is hosting four tree climbing workshops. The first two were in early June, the Women’s Tree Climbing Workshop (WTCW) and the Advanced Tree Climbing workshop. Both workshops were taught by an all-female instructional team. These workshops brought members from across the Chapter. Both the U.S. and Canada were represented. A huge thank you to the WTCW committee for acquiring sponsorships, reviewing scholarships, and coordinating details and logistics for these workshops!

In August 2019 PNW-ISA will offer two climbing workshops at the Washington Park Arboretum in Seattle, WA. Read More "Check Out Our Tree Climbing Workshops This Summer!"

PNW-ISA 2nd Women’s Climbing Workshop A Success!

Melissa Amrhein
PNW-ISA Education Program Manager
Learn more about Melissa Amrhein.

PNW-ISA hosted its second successful Women’s Tree Climbing Workshop on June 7-9, 2019 in Seattle, WA. International Tree Climbing Championship competitors Bear LeVangie and Melissa LeVangie flew in from the east coast to teach along with a top notch instructional team including Rebecca Seibel-Hunt, Kate Tarkington, Jamilee Kempton, Kali Alcorn, Krista Strating and Maria Tranguch. The group was engaging, enthusiastic, genuine and knowledgeable. What a team!

Participation was diverse. Women traveled from out of state and out of country to participate. Experience levels ranged from no previous climbing to those that wanted to improve specific skills. Every participant made big leaps towards their goals. It was empowering to observe the transformations that occurred in such a short period of time.
Read More "PNW-ISA 2nd Women’s Climbing Workshop A Success!"

Trees and their Associates

Phil Bennett Phil Bennett
Learn more about Phil Bennett.

How often do we think about tree associates when we are working on an individual tree?  The sixteen chapters of the Arborists’ Certification Study guide cover many areas of Arboriculture, but there isn’t a chapter dedicated to tree associates.  The problem here is that we may be preconditioned by our training to think of trees as individual entities, rather than the interconnected organisms they are.

Some tree associates cause us problems (or perhaps, opportunities) as Arborists.  English Ivy, fungal root rots such as laminated root rot and invertebrates such as aphids spring to mind.  What about the beneficial, or symbiotic relationships trees have with other organisms?

We know that trees benefit greatly from fungal associations, and that mycorrhizae in the soil greatly increase the uptake of water and nutrients into trees.  However, it doesn’t stop there. The research of Dr. Suzanne Simard has shown that the mycelial networks carry information, including “threat signals” between trees.  Simard has also shown that symbiotic relationships exist between some tree species such as Douglas fir and paper birch, and that they exchange resources below ground, using the mycelial network as an intermediary.  For more information, watch this TED Talk.

Lichens are also important tree associates, and some species provide distinct benefits to trees.  Lobaria species are nitrogen-fixers, and when they shed from the upper parts of the tree, and fall to the ground, this nitrogen is made available for uptake into tree roots.

The last association I’ll mention is between salmon and trees.  Trees provide shade over streams and rivers, which benefit salmon as they need cooler temperatures to survive and thrive.  Young salmon leave their home streams, and swim to the ocean where they feed and grow much larger. They bring the gift of nitrogen back to those same streams, and that nitrogen is distributed into the forest after they spawn and die by other animals such as bears, ravens, and coyotes.  Historically, there was a correlation between the size of annual ring growth in trees and the size of the salmon run that year. The reduction in salmon populations has greatly affected this association, and its benefits. More details can be found in David Suzuki and Wayne Grady’s excellent book “Tree: A Life Story”, which details the life of a Douglas fir from seed to death.

Friends, I know I’m stretching here, and that my last example doesn’t have as many implications for arboriculture as for traditional forestry.  My argument is that we need to consider that trees don’t exist in a vacuum, even when we seemingly put them in one, such as a small tree-planting lawn between the street and sidewalk.  Their associations with birds, invertebrates, lichens, other epiphytes, and fungus still exist and have implications for the tree itself, and the wider environment.

Some questions we could ask when prescribing a treatment, bidding a job, or working on trees are:

  • How will this affect tree associates, and what are the implications of that?
  • Can I mitigate the impacts to associated organisms?
  • How can I communicate these associations and their implications to the customer?
  • How can my work include tree associates as well as trees?

Asking these questions might help us learn more, increase our scope-of-practice, benefit the customer and the environment, and provide a market opportunity.

signed, Phil.

ANSI A300 Standard

Zeb Haney Zeb Haney
Tree Resource
Learn more about Zeb Haney.

Twice each year a group of arborists meet to discuss the practice of arboriculture. These are your peers and represent large utility companies, small businesses, and public entities. These hardworking volunteers are collectively known as the Accredited Standards Committee (ASC) A300.

The committee develops consensus based on current research and practices that cover ten aspects of tree care. Each standard is meant to aid in establishing standards and written specifications for performing tree care assignments. Read More "ANSI A300 Standard"

The Ethical Branch

Dylan Saito Dylan Saito
Learn more about Dylan Saito.

In the PNW, we bear witness to best management practices (BMP's), and seemingly the worst as well. I feel a tide has changed much with the climate in our industry. It appears more PNW Arborists are well-aligned with our code of ethics and BMP’s, and some may have continued to use “loopholes” to cut corners, or an assimilated professionalism to sustain a career. Whether or not you are one or the other, we must continue to learn and engage each other with “proper practices". It makes our industry stronger and respected among the world community. This may translate into greater opportunities, if desired, or more jobs/fields in which we may guide our success for the planet, or profit, or both. Read More "The Ethical Branch"

American Hornbeam Cultivars – Carpinus caroliniana: Native Flame®, Palisade®, Ball O’ Fire™, & Rising Fire®

James Barborinas James Barborinas
Urban Forestry Services, Inc. & Urban Forest Nursery, Inc.
Learn more about James Barborinas.

In a Tree Profile over 10 years ago, I raved about the American hornbeam, Carpinas caroliniana and still feel the same today. With the more recent arrival of several new cultivars which display some of the best characteristics of this species, an update on this tree is in order.

Let’s start with its generic attributes. The pioneer nicknames of “Blue Beech”, “Muscle Tree” or “Ironwood” of the species are suggestive of what a tough Midwest native tree this is. Considered a small tree, the ultimate mature size is approximately 30-feet tall by 20-feet wide. They may grow larger under optimum conditions. It has few, if any, disease or insect pest concerns in this region and as the name implies, has branches “of steel”. In my experience, branches can bend like rubber and not break, which is a good testament for strength. This is a good urban tree characteristic.
Read More "American Hornbeam Cultivars – Carpinus caroliniana: Native Flame®, Palisade®, Ball O’ Fire™, & Rising Fire®"