Saving the Butternut Tree
An Invasive Fungus Has Infected Almost the Entire Native Population In The N.E.
The butternut tree, which is native to the northeast, is difficult to find these days. Like with Dutch elm disease and the chestnut blight, an invasive fungus is killing the species. As part of a collaboration with northeast stations, Vermont Public Radio’s Jane Lindholm reports on efforts to save the butternut.
Kathleen Osgood Dana walks into the forest surrounding her home in Northfield, Vermont. She stops in front of a huge tree stretching high above the forest floor.
“This butternut was here when my family moved here in 1956. And the butternuts dominated this entire hill so my father named it Butternut Hill.”
As a child, Dana collected the nuts to make maple butternut ice cream. And her kitchen cabinets are made out of the hardwood. But over the years she’s watched this tree—like others on the hill—slowly die.
“If you look up this left trunk, see it’s still trying to make some leaves up there. But this right trunk has died entirely. You look up and it’s all dead.”
What’s killing Dana’s butternuts is an invasive fungus that has infected almost the entire native population east of the Mississippi.
Vermont Forest pathologist Dale Bergdahl is an expert on the disease, called butternut canker. Pointing to an infected tree in a park in Northern Vermont, he says the disease is easy to spot.
“You’ll get these areas of dark discoloration, kind of like soot, on the bark, oozing from these areas of infection. A single canker’s not a big issue…"
But over time, multiple cankers surround the tree and essentially strangle it. Bergdahl and a team of scientists from around the northeast are trying to develop a new strain of butternut that will resist this disease. Like a detective, Bergdahl is searching for the few butternuts that are still thriving, despite the disease. He travels all over New York and New England taking samples. But it turns out identifying a butternut tree isn’t so easy. Sandra Anagnostakis, a scientist at the Connecticut Agricultural Experiment Station is one of the researchers working on the restoration project.
“What we’re finding is that in Northern Vermont, most of the trees are butternut. The further south we get, say in Massachusetts, half of them were butternuts and half of them were Japanese walnuts or hybrids. In Connecticut, almost all the trees were hybrids or Japanese walnuts.”
The reason for the discrepancy could lie in economic differences that once divided the region. In the 1800s, Americans began importing Japanese walnut trees. The walnut is easier to crack than the butternut. But northern farmers couldn’t afford these trees.
“Whereas anybody who was in the affluent New York, Connecticut, New Jersey area probably would have seen trade magazines with advertisements for Japanese Walnuts and heard the raves about what wonderful trees they were and would have been apt to spend their money on getting a few of them.”
The hybrid offspring of those walnuts are now making scientists’ job more difficult. All butternut samples have to be sent to a plant geneticist for identification. When they find a pure butternut, scientists graft its branches onto black walnut root stock. If these new seedlings can resist the deadly butternut canker, they will be bred into super butternuts that can begin to re-grow the population. But Anagnostakis says that will take at least a decade.
“Well, you have to think in tree time here. Nothing to do with trees is ever very fast.”
Back in Northfield, Vermont, Kathleen Osgood Dana is willing to wait. Samples from two of her remaining butternut trees were taken last winter.
“I don’t know that any of the materials that we have from these living butternuts are going to be any good. But if they are, that’s a legacy.”
A legacy she hopes will continue on her property on butternut hill for her grand kids to enjoy.
Northeast environmental coverage is part of NPR’s Local News Initiative.