At the corner of Route 73 and 9N, overlooking a snowcapped ridge of Adirondack peaks, a 60-foot tall elm tree stands sentinel at the edge of a wetland valley. A popular stop for photographers and tourists, its sweeping branches provide a foreground to the mountains. This elm tree has also captured the attention of scientists. Only a few yards away, a grove of elms has fallen victim to Dutch Elm Disease. On Monday scientists from the Nature Conservancy took samples of the healthy tree.
It’s a sunny and windy day as the Nature Conservancy’s Connecticut River program Flood Plain Forest Ecologist Christian Marks gets his gear out to collect branches from an elm tree that stands just off the roadway. Nature Conservancy scientists across the Northeast are seeking out older healthy elms, particularly those near smaller elms with the disease. They collect branches from the healthy trees to cross-pollinate in hopes they can propagate disease resistant trees.
American elms once were dominant in the northern U.S. and southern Canada. Marks is one of the scientists in the Northeast working on the American Elm restoration project. “The Nature Conservancy can help by finding elms that are potentially resistant like this exceptionally large surviving tree here where there’s another elm just over there that’s died and has bark beetle galleries on it. So clearly the bark beetles that spread the disease are in this place. This tree is probably over a hundred years old and has been exposed to Dutch Elm disease multiple times in its life and there’s a good chance it has some resistance to the disease. We’re going to take some cuttings from this tree to propagate it vegetatively as well as to try to collect some pollen. And then we’ll do crosses with other trees that researchers have already found to have elevated tolerance to the disease and hopefully some of the offspring will be even more tolerant.”
Marks often has to climb elm trees to collect the sample branches but with this one, its branches arch nearly to the ground and allow him to use pole loppers.
“Show you the next step. So I’m putting a moist piece of cloth around the cut end so that they don’t dry out in transport.”
The box of buds and pollen samples will be couriered overnight to laboratories for crossbreeding and cloning.
Gus Goodwin, Conservation Coordinator with the Vermont Chapter of the Nature Conservancy, once interned with the Adirondack chapter and found the tree for the propagation project. “There are two types of buds on the tree here. These ones are the leaf buds and they tend to be a little bit more terminal on the twig. And then these ones are the flower buds here and they’re a bit larger. So these are the ones that we want to harvest. (The large flower buds?) Yeah. (So not all of those are leaf buds then?) Um-hum. Right, yeah. And one of the things that we look for in a tree is kind of the ratio of leaf buds to flower buds. And so a tree that’s in pretty good vigor and good health will produce quite a lot of these leaf buds and so you know a tree like this looks fairly healthy to me.”
Christian Marks walks over to a nearby grove of dead elm trees, explaining that the disease is invasive. “The American Elm was never exposed to Dutch elm disease before it arrived from abroad and so it was completely a naive host and now it has to evolve defenses against this host. And that’s really what we’re trying to do is to help that evolution along, to basically speed it up by breeding. I like to joke that I run a dating service for elms where I’m bringing together two disease tolerant elms that might not meet on their own, you know one from New Jersey and one from Minnesota, and then they can cross and hopefully have even more disease tolerant offspring.”
The samples are being sent to laboratories of the U.S. Forest Service Northern Research Station.
The elm tree is on state land and a DEC research permit was obtained, allowing the Conservancy scientists to cut the sample branches.