Archive: Around Town

Efforts to battle an invasive forest pest just got a boost from a New York State Department of Environmental Conservation grant that enables Cornell Botanic Gardens to continue – and expand – its work to conserve hemlock trees that are foundational to the university's campus and natural areas.

Ecologists refer to hemlocks as a "foundation species" for the plant communities in which they grow because the trees have a profound influence on the survival of other organisms. This state Invasive Species Rapid Response and Control grant will be used over three years to control hemlock woolly adelgid, an invasive aphid-like insect wiping out hemlock populations across eastern forests.

"Hemlocks promote a cool, moist environment near gorges and stream corridors that many other species require," said Todd Bittner, Cornell Botanic Gardens' director of natural areas. "Without these conditions, plant and animal diversity is diminished, ground and water temperatures increase, and stream flow changes, putting species and habitats at risk. There is more to lose than just hemlocks."

To control this invasive pest and conserve hemlock stands, insecticides are administered in single-tree treatment through trunk injections or bark applications. Since 2009, Cornell Botanic Gardens has treated and saved 3,000 hemlock trees around Beebe Lake, Cascadilla and Fall Creek gorges, and other important natural areas on and off campus. The pesticides translocate to the growing branches where the adelgids feed, and the treatment remains effective for seven or more years.

With the support of the $68,723 grant, more than 1,200 trees will be treated. The grant also funds efforts to identify new hemlock woolly adelgid infestations and to research the effectiveness of biocontrol agents. The latter is in collaboration with Cornell forest entomologist Mark Whitmore, extension associate in the Department of Natural Resources in the College of Agriculture and Life Sciences.

Whitmore is developing biological control agents that keep the hemlock woolly adelgid population in check. These biological controls include three insects, Laricobius nigrinus, Leucopis piniperda and Leucopis argenticollis, that originate from the Pacific Northwest and are expected to work in concert with one another as predators of the adelgids. The latter two species, both silver flies, will be released and tested in Cornell Botanic Gardens' hemlock forests in the spring of 2018.

The public can play a vital role in helping land managers know about new hemlock wooly adelgid populations and track its spread by learning what to look for and reporting positive and negative sightings via Cornell Botanic Gardens' website.

"We are at the beginning of a long road," said Whitmore. "There is more research that needs to be done, but I am hopeful for the hemlock forests."

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