Aug 2023

The lingering ash orchard at the Holden Arboretum in June 2023 Photo Anna Funk Holden Forests and Gardens

The lingering ash orchard at the Holden Arboretum this June. (Photo: Anna Funk/Holden Forests & Gardens)

Hi all, 

Hope you’ve had a great summer. How's the search for lingering ash going? Would your organization start a lingering ash orchard? Looking for updates on eastern hemlock management, or the latest tree and pest research? See below! Keep an eye out, it looks like it will be a good year for hemlock cones and beech nuts!! 

 — Rachel Kappler

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The Latest

American beech

  • Researchers continue to unravel information about the nematode that causes beech leaf disease, working on genomes, symptom development, and modes of travel. We’ll continue to add any new research released to the Research Roundup section of this newsletter, below.

  • Although we have to contend with beech leaf disease, we are still interested in reports of trees that are potentially resistant to beech bark disease (see Get Involved, below). The best way to conserve these trees is to graft branches onto other local rootstock; it's difficult to keep beech seeds preserved.


  • Lingering ash searches in Ohio and Michigan this summer have found a handful more lingering ash to test. It’s not surprising there are so few given lingering ash trees make up less than 1% of the population (Knight et al. 2012).

  • New plans are in place for lingering ash orchards at the Oconto River Seed Orchard in Wisconsin and at Cornell University in New York. These orchards will be filled with grafted copies of local lingering ash for long term observation and to conserve specimens that have not yet gone through the testing process.

Eastern hemlock

  • We’ve made a few updates to the lingering hemlock monitoring protocol, which can be found on the GLB FHC webpage. This is the protocol that the TNC Trees in Peril working group created to help organizations know what data is needed when monitoring potentially resistant eastern hemlock. More updates may come this winter after field testing the protocol.

  • Program managers with the Hemlock Wooly Adelgid National Initiative met in Blacksburg, VA at the end of June. Find a program summary (under “reports”) and more information on their Meeting Materials site.

Have an update to share in the next GLB FHC newsletter? Email us!

Partner Spotlight:

Dr. Jill Hamilton Lab, Pennsylvania State University

Jill Hamilton lab at Penn State courtesy Jill Hamilton

The Hamilton lab. (Photo: Courtesy Jill Hamilton)

Dr. Jill Hamilton is the Director of The Schatz Center in Tree Molecular Genetics, and the Ibberson Chair of Silviculture Research in the Department of Ecosystem Science and Management at Pennsylvania State University. The Hamilton lab studies the distribution of population genetic variation across the landscape, with the end goal of understanding adaptive potential of populations under climate change and related threats to species.

For one of the lab’s core projects, they’re collecting seed and leaf tissue samples for Fraxinus pennsylvanica, F. americana, and F. nigra for genomic analysis. They’re studying the relationships between genes and the environment across these species’ ranges, as well as developing resources to complement EAB-resistant breeding materials. 

This summer, Ph.D. student Kyra LoPiccolo, in collaboration with The Nature Conservancy, led collections of leaves from ~1,000 trees across the three species and 60 U.S. locations. Sampling efforts will continue into the fall, aided by volunteers across the country recruited by Adventure Scientists. These range-wide leaf collections will allow LoPiccolo to study the genomic diversity of each species, characterize the structure of the genetic variation across each species range, and learn more about the trees’ adaptive potential. 

>> Volunteer to help collect ash samples and learn more at the Adventure Scientists website.

LoPiccolo, alongside postdoctoral scholar Dr. Melissa Lehrer, is also starting to germinate black ash seed received last year from over 400 maternal trees across the U.S. and Canada. As the seeds come out of cold stratification, they’ll be used to establish common garden experiments, where genetically related trees are planted across a range of environments. This will allow her to study how the genes of the different ash populations interact with different environments.

Get Involved

Meet your partners

Our partners list is getting long! Head to the GLBFHC homepage and scroll down to the bottom of the “About Us'' section. We’ve posted the list of current partners, with primary contacts for each organization. It’s divided into two:

Active Partners – those currently organizing resistance breeding related activities

Networking Partners – those interested in starting related activities

Click the links above to see the lists now! 

Need to edit your info on the partners lists? Email to help us keep these accurate and updated.

Accessions of eastern hemlock with the National Seed Lab as of August 14, 2023. More were added in 2021! (Credit: USDA-ARS U.S. National Plant Germplasm System)

Collect seeds

In the upcoming quarter, we could use help from our partners and allies with eastern hemlock seed collection! The map above shows both old and new accessions from 2021 — we’d love to expand the collection to new areas from which seed has not been previously banked. If you have eastern hemlock seeds, especially from an area not marked above, please consider sending some to the National Seed Lab for long term storage. This effort will help with future conservation & tree breeding efforts of eastern hemlock. 

The National Tree Seed Centre (NTSC) in Canada is also looking for more eastern hemlock and ash seed. Visit the NTSC website for more information, and please contact Donnie McPhee, NTSC coordinator, before sending in seed to make sure you include all necessary information with your submission.

Start an orchard

We’re looking for more organizations that can host a long-term lingering ash orchard in the future. Please reach out if you are potentially interested, and let us know how much space you have and whether you’d need funding to help get it started. Already-running nurseries and orchards are great contenders, but placing orchards on state land or conservation easements may also be possible.

Report lingering trees

There's still time to report lingering trees! From mid-May to August is a great time to look for healthy ash and beech that are lingering in otherwise-infected areas and may be resistant. It’s an enormous help to us to know where these trees are located! We work with our partners near each reported tree to get it incorporated into breeding programs. Report tree sightings with the TreeSnap app (U.S. and Canada) or by emailing us directly at

Set up a workshop

As always, training workshops to help with seed collection, using the TreeSnap app, and more are available online or in-person, — contact Rachel today to set one up for your organization!

Research Roundup
  • Why have blue ash fared so much better than white? In just a six-year span, what had been a full canopy of white ash had less than 20% remaining, while blue ash still held on to nearly 90%. Researchers from Wright State University in Dayton, Ohio, examined trees and found very few instances where EAB larva had attempted to feed on the blue ash, whereas all the white ash had been attacked. In lab trials with cut stems, EAB fed less and grew significantly more slowly on blue ash. [Cipollini & Morton 2023 Agricultural and Forest Entomology]

  • Extreme cold kills HWA — for now. Winter HWA mortality is high when extreme low temps for the season fall below −20 to −30°C (-4 to -22°F). A team out of Michigan State University made Great Lakes region climate models to project these minimum temperatures into the future, finding that locations within 10-25 km (6-16 mi) of Lake Michigan’s relatively warm shores may be protected from these potentially lethal temps, and that climate change will likely allow northward expansion of HWA region-wide in the future. [Kiefer et al. 2023 International Journal of Climatology]

  • Successful lingering ash trials, plus contenders for mechanism of resistance. First-generation offspring of lingering green ash (F. pennsylvanica) killed significantly more EAB larvae than the offspring of susceptible parents. Molecular analysis revealed the resistant trees had elevated levels of secoiridoids and aromatic alkaloids. Further study will be needed to confirm whether these metabolites are what confers the resistance. [Stanley et al. 2023 Frontiers in Forest and Global Change]

  • Canopy gaps give HWA-infested hemlocks a boost. Researchers tested two gap sizes and two gap creation methods to see how infested hemlocks might benefit. All canopy gaps were positive — the authors suspect the increase in sunlight and other resources improves the physiological tolerance of eastern hemlock to HWA infestation. [Mayfield III et al. 2023 SSRN (preprint)]

Have new research to share in the next GLB FHC newsletter? Email us!

In the News

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