Planting the experimental elms on Bloomfield Farm. Pictured from L to R; Mike Cranney, Louise Clarke, Sabine Nix, Maggie McNulty, and Dr. Lara Roman (standing)

Morris Arboretum and the Campus Arboretum at the University of Pennsylvania are participating in an experiment by the USDA Forest Service study to test American elms (Ulmus americana) for their tolerance to Dutch elm disease (DED).

This disease, first reported in the states in 1928, has decimated elms in Europe, North America and other continents. Other tolerant elm cultivars, such as ‘Valley Forge’ and ‘Princeton’, are available in the nursery trade and are widely planted in our landscapes. While not immune to DED, these trees perform well even in our urban areas.

The Forest Service experiment, led by Dr. Lara Roman and Dr. Vince D’Amico in the Forest Service Philadelphia Field Station, Dr. Leila Pinchot and Dr. Charlie Flowers from the Forest Service lab in Ohio, along with Dr. Tara Trammell and masters student Danielle Mikolajewski from the University of Delaware, involves planting and monitoring the test elms in Philly, Newark DE, and Columbus OH. There are 15 sites per city and 3 trees per site, making 45 total trees per city. The University of Pennsylvania and Morris Arboretum are home to four of our city’s sites.

The tested elm varieties have been bred from survivor trees; one survivor was found on a farm in Michigan, the two other have been crossed with the cultivar ‘Valley Forge’. These new varieties were bred in the Forest Service lab in Ohio.