MONTPELIER, Vt. — Efforts to develop a version of the American chestnut tree that is resistant to a blight that almost wiped out the species are making progress, yet it could be a century before the trees can offer much economic benefit to the Vermont economy, a scientist told a Vermont legislative committee Thursday.

Kendra Gurney, the New England regional science coordinator for The American Chestnut Foundation, told the committee that her organization has helped create a blight-resistant version of the tree that is just now ready for widespread field testing.

Over the next several years, those versions will be refined in hopes of producing a tree that could be planted throughout the former range of the American chestnut, from Maine to Georgia.

“At some point we will get to the Johnny Appleseed stage where we know we have ‘the’ tree, we know everything is going to do well and we can start getting it out to landowners, because that’s really what people have been waiting for,” Gurney said after briefing the House Committee on Agriculture and Forest Products. “They want to know that if they plant these things, they probably won’t die.”

She estimated they are about 15 years from that point.

The American chestnut tree was once one of the dominant species in forests from Maine to Georgia.

The fast-growing tree was known for its chestnuts, and the wood is resistant to rot and can still be found in some old barns.

But the species was nearly wiped out by a blight from Asia that was first identified in 1904. Now, there are few mature trees in the forests, but immature trees continue to grow until they are killed by the blight.

The foundation, which has state chapters throughout the former range of the tree, helped develop a blight-resistant species by crossing American chestnuts with a resistant Chinese variety.

Vermont is at the northern edge of the tree’s range and mature trees can be found that have escaped the blight, Gurney said. The tree that is believed to be the largest American chestnut in Vermont is among a group of a handful of the trees on private land in Berlin.