NORTHAMPTON — While genetics research may call to mind petri dishes and lab coats, reaching for a solution sometimes requires leaving the laboratory. Once in a while, it requires defying gravity.
On Thursday morning, researcher Christian Marks, arborist James McSweeney of Hilltown Tree and Garden in Chesterfield, and Kim Lutz, director of the Connecticut River program for the The Nature Conservancy, gathered off Damon Road to collect samples from a mature healthy elm that stood roughly 50 to 60 feet high.
For the past six years, Marks, a research associate with The Nature Conservancy, has been scouring the floodplains of New England searching for healthy mature American elm trees in the hopes of propagating the traits that have protected them from the devastating Dutch elm disease. American elms are most abundant in floodplain regions.
“This is a great elm habitat, a perfect place to look for elms,” Marks said. “There are also some rare trees here like that native butternut walnut,” he said as he pointed out the one lone tree near the river.
The conservancy recently was awarded a five-year $1.4 million grant from the Manton Foundation based in new York City to help this research.
On Thursday, McSweeney showed up for the job with his sidekick, a goat named Luna who looked on as he prepared his rigging and hauled himself high up into the canopy of the tree to harvest branches containing pollen and leaf buds.
Once harvested, Marks carefully wrapped the branch ends with a wet cloth and plastic to prevent drying out during shipping, and placed them in a large box marked fragile.
The samples will be sent to the Northern Research Station of the U.S. Department of Agriculture Forest Service in Ohio. There a team will try to propagate disease-resistant elms by crossing Marks’ samples with trees that the Forest Service has proven are highly tolerant to Dutch elm disease.
The offspring from the controlled crosses will be planted in floodplain forest restoration sites.
“Geneticists will examine the trees’ genetic resistance,” Lutz said. “They are looking for disease resistance but also for cold hardiness —that is important.”
Complicated process
This work is a lengthy and involved procedure.
“We don’t know what the genes are for resistance,” Marks said. “We know it involves multiple genes. That is what we are trying to identify, and that is one of the things that makes it complicated.”
And finding healthy trees that are cold-hardy is like looking for a needle in a haystack.
Marks has surveyed 95 floodplains looking for healthy trees.
“I don’t think there has been anyone in the floodplain as much as Christian has to find these trees,” Lutz said.
Marks explained, “I have a couple hundred trees on my list, and most are probably just lucky rather that resistant. There will likely be less than 50 trees that we collect at the end, and from those, 10 that are disease-tolerant. But it is still good because it means that we are adding to the genetic diversity.”
This year, Marks will take samples from 20 trees that he has found in locations ranging from northern New Hampshire to southern Connecticut and from the Pioneer Valley to the Taconics in eastern New York.
“After we get these, I am going to an elm in Chesterfield, then to Vermont,” Marks said of his plans for Thursday.
Remaining samples will be taken within the next week before the warmer weather hits.
Trees that were propagated from samples taken in 2013 have been planted, but they are not yet large enough to test for disease resistance.
Because the Vermont Forest Service is currently working on revitalizing floodplains in its region, Marks has planted propagated trees there.
“This benefits two projects at once by planting them in the Northeast Kingdom,” Marks said.
Dutch elm disease
According to Marks, there are three group studies in North America that are engaged in this research to understand genetic resistance to Dutch elm disease — The Nature Conservancy and U.S. Forest Service; the universities of North Dakota and Minnesota; and the University of Guelph in Ontario, Canada.
“One advantage of doing this work in southern New England is that the disease has been around here for so long and the surviving trees have lived through at least three waves of the disease,” Marks said.
Dutch elm disease is a fungal pathogen that grows within the vascular tissue of the tree, clogging its water-conducting system and causing leaves to become discolored, wilt and drop, eventually killing the tree.
It is spread when the roots of trees growing close to one another become grafted together, or by the activity of bark beetles, which transport pollen from one elm to the next. Once the tree dies, the beetles also eat the dead bark of the elm.
According to Marks, the disease, originally of Asiatic origin, has been in the U.S. since about 1928, when logs from diseased trees in Europe came through the harbor in New York City carrying bark beetles.
“All along the railway line, bark beetles came out of the logs and spread the disease,” he said.
According to Lutz, the loss of American elms in the floodplains has compromised their forest structure.
Healthy, intact floodplain forests provide habitat for wildlife and act like a sponge, helping to control flood levels during heavy rains as well as filtering out sediment and pollution before reaching the rivers.
The American elm was once the dominant tree species in Massachusetts, both in floodplains and majestically lining many a neighborhood street — but that is just a memory for many people.
“When I talk to older people, they really appreciate this project because they can remember when the streets were lined with elms,” Marks said. “Younger people, kids in college just don’t have that experience.”
Fran Ryan can be reached at Fryan.gazette@gmail.com.