Cornell researchers are trying to stop one of North America’s most destructive tree killers with a new wave of genetically resilient ash trees.
According to a report by Krishna Ramanujan for the Cornell Chronicle, the university has become New York’s first propagation center for ash trees that may resist emerald ash borer insects — invasive pests that have decimated ash forests in 37 states and cost billions in damage.
The project is part of The Nature Conservancy’s national Trees in Peril effort. At Cornell, staff have planted 139 young black, white, and green ash saplings, all grafted from 26 “lingering ash” parent trees that survived borer attacks. These trees are believed to carry unique genetics that could protect future generations from the beetles.
The work is being led by the Cornell Botanic Gardens, with natural areas director Todd Bittner overseeing the effort. Bittner said their goal is to conserve trees from 50 to 60 genetically distinct parent trees. If successful, the saplings will not only survive but serve as the next source for cuttings to propagate even more resistant ash trees.
The insects, which burrow into trees and destroy tissue beneath the bark, are nearly always fatal to untreated ash. But some trees — known as lingering ash — can stop the larvae from spreading. Researchers say some of these trees wall off the pests before they can cause fatal damage. Others may be chemically invisible to the borers, producing fewer volatile organic compounds (VOCs) that the beetles use to locate host trees.
The university is working with the Ecological Research Institute to locate lingering ash across New York and collect samples for cloning. More propagation sites are expected to open across the region.
The conservation effort also carries cultural importance. Black ash has been used for generations by Haudenosaunee communities in New York and Canada for basket-weaving, ceremony, and other traditions. Preserving the species means protecting both forest health and Indigenous heritage.
Cornell hopes to begin testing resistance in the newly planted trees within the next decade, once they are large enough for emerald ash borers to target. In the meantime, staff will continue protecting and monitoring the saplings as they grow toward becoming the foundation of a restored ash population.
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