November 2022

Hi all, 


We’ve made it to the fourth quarter! Here at the Holden Arboretum, it’s been seeds, seeds, and more seeds — and that’s a good thing. Our efforts to collect lingering ash seeds from across the region have been a success. Read on to learn more about that and our latest announcement: We’re working on launching a Lingering Hemlock Symposium with NC State in spring 2023. We hope you can join us! 


Finally, we’re working on compiling our annual report. If you or your organization — especially if you’re a GLBFHC partner — has any updates or achievements to share from calendar year 2022, please email me. Thank you.

-Rachel Kappler

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The Latest

American beech updates:

Beech leaf disease continues to spread through Michigan: BLD was first reported in Michigan in July 2022, but the condition of infected trees in St. Clair, Oakland, and Wayne counties suggest it’s been around for at least a year already.

Ash updates: 

We asked, you answered: Thanks to those who sent in lingering ash seeds! We’re still processing them, but so far we have seeds from 8 locations across 2 states that came from lingering ash. With these seeds, we’ll start plans for future research projects, involving assessing their EAB resistance with bioassays and long-term lingering ash orchards.

Eastern hemlock updates: 

Save the date: Spring 2023 Lingering Hemlock Symposium with NC State! We’re working on putting together a symposium for next spring in Asheville, North Carolina. Since we’re still looking for the venue, the exact dates are TBD (we’re aiming for April). If you might be interested in attending and/or presenting, please let us know by filling out this short form so we can keep you updated!


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

State Spotlight: Michigan

Beech leaf disease was first detected in Michigan in July 2022, and experts throughout the state have been on the case. In January 2021, over a year before it was first detected, BLD was added to the state’s invasive species watch list. Michigan State University researchers are currently surveying the state, and University of Michigan researchers have plans for survey and outreach efforts in 2023. DNR and Michigan Department of Agriculture and Rural Development professionals are currently working with partners on survey and research proposals as well as outreach efforts in affected areas in southeast Michigan.


Michigan also continues to address hemlock woolly adelgid infestations along roughly 110 miles of the Lake Michigan shoreline. Survey and treatment activities allow the State of Michigan and its partners to slow the spread and eradicate local infestations before they become established, protecting over 170 million hemlocks playing a critical role in preserving Michigan microclimates.


In addition, Michigan continues to move forward with ash resistance work to mitigate impacts by emerald ash borer. A seed orchard of resistant ash has been established to help with restoration efforts after the emerald ash borer’s devastating wave of damage swept across the state. Continued collaboration with the Great Lakes Basin Forest Health Collaborative, USDA Forest Service and other partners will ensure that ash trees remain a critical component of Michigan forests.


Thank you, Michigan foresters, for all your great work!

Get Involved: Report HWA and BLD

The number one thing we need from our partners and allies right now is reports of Hemlock Woolly Adelgid and Beach Leaf Disease. 

We’re tracking the spread of Hemlock Woolly Adelgid. Observations are particularly critical in the lime green counties on the map above, where HWA has not yet been reported (as of January 2022). 

For beech leaf disease, we likewise ask forest professionals to keep a close eye out for BLD and to report sightings, especially in counties where it has not yet been reported (above, as of July 2022). 

How to submit observations: There are a number of ways to report HWA and BLD. You can submit observations through the citizen science apps TreeSnap or iNaturalist. The Tree Health Survey app is still the primary place for individuals to report beech leaf disease. You can also send a report through the Midwest Invasive Species Information Network (MISIN) website.

Research Roundup
  • Gap dynamics and disease-causing invasive species drive the development of an old-growth forest over 250 years. Researchers from Ohio’s Baldwin Wallace University looked at 250 years of tree rings in an old growth forest to map out recruitment, disturbance, and growth patterns over time. The biggest impacts? Disease-causing invasive species. [Flinn et al. 2022 Forest Ecology and Management



  • Assessing beech bark-diseased forest canopies over landscapes using high resolution open-source imagery in an ecological framework. Looking for beech bark disease? Just look for the yellow crowns. Spatial analysis can identify hotspots and help with forest health assessment. [Barnett et al. 2022 Forest Ecology & Management


  • Phenology and Voltinism of Emerald Ash Borer (Coleoptera: Buprestidae) in Central North Carolina. Researchers from NC State tracked emerald ash borer life cycles to figure out when the larvae (which are susceptible to parasitoids) are present. In central North Carolina, they were present late June to October — these results can be applied to other areas based on climate conditions (~1,100–3,000 degree days base 10°C) to target biocontrol efforts. [Bohannon et al. 2022 Environmental Entomology]


  • Introduced plants induce outbreaks of a native pest and facilitate invasion in the plants' native range: Evidence from the emerald ash borer. Evidence suggests that planting of American ash trees in China — EAB’s native range — made EAB worse there and may have primed the invasion of EAB to North America. [Dang et al. 2021 Journal of Ecology]


  • Top-down regulation of hemlock woolly adelgid (Adelges tsugae) in its native range in the Pacific Northwest of North America. Researchers found that HWA is limited by natural predators in its native range — evidence that biocontrol might be an effective option for management. [Crandall et al. 2022 Oecologia]


  • Tree breeding, a necessary complement to genetic engineering. In this new review, C. Dana Nelson outlines why and how tree breeding and genetic engineering benefit one another. [Nelson 2022 New Forests


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

Trees in the News





GLB FHC in the news:









The Great Lakes Basin Forest Health Collaborative is an initiative co-sponsored by Holden Forests & Gardens and the USDA Forest Service, funded through the Great Lakes Restoration Initiative
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