Monthly Archives: December 2013

American Elm Expert Tom Zetterstrom Shows TreeKeepers How to Prune Young Elms in Patterson Park

After delivering his lecture on "Return of the American Elm," on Saturday morning February 1 at Cylburn Arboretum, Tom Zetterstrom, founding director of Elm Watch, then led a dynamic afternoon workshop on pruning young American elms in Patterson Park. Twenty people, including several professional arborists and many TreeKeepers, learned from Zetterstrom how to best shape this particular cultivar, Valley Forge. Participants took turns sawing and cutting branches as they practiced  creating a durable and pleasing tree architecture.

 “The goal,” says Zetterstrom, when pruning American elms, “is to develop a dominant leader and strong, staggered branch unions. Aesthetic and functional objectives are also considered—complimenting architecture, providing needed shade, respecting and restoring historic treescapes, avoiding line-of-sight and utility line conflicts.”

Pruning a branch Photos courtesy Russ Moss

Zetterstrom is the recipient of the Public Awareness of Trees Award from the national Arbor Day Foundation and is widely recognized for his involvement with American elm restoration. He became captivated by American elms through his work as a fine arts photographer. His “Portraits of Trees” photographs are in the collections of three-dozen museums, including the Metropolitan Museum of Art, the Corcoran Gallery, and the J. Paul Getty Museum of Art. 

In his talk, “Return of the American Elm,” Zetterstrom illustrated how this one iconic tree has long connected people to their land and communities. He spoke engagingly about  the civic prominence of the American elm in the Northeast in our early history, and the devastating post WW II loss to Dutch elm disease of a hundred million street trees nationwide, including here in Baltimore.


Baltimore City Arborist Erik Diehl opens the elm lecture Photo Courtesy Russ Moss

Baltimore City Chief Arborist Erik Diehl introduces Zetterstrom In recent years, Baltimore and other cities are again planting the new disease tolerant American elms. Zetterstrom discussed the pros and cons of new diverse cultivars, the right tree for the right place, planting techniques for large root zone trees, and designs for sustainable streetscapes, parks, parking lots, and campuses.