Barking up the right tree: large American elms scarce in St. Lawrence County
Sunday, April 6, 2014 - 5:57 pm

By PAUL HETZLER

For centuries, the American elm was esteemed for providing the best roofing and siding for dwellings of all sizes. Elm also furnished material for items as diverse as grain storage bins, snow shovels, grain scoops, baskets and spoons. Before Dutch elm disease reached the New World, the trees provided native peoples with prodigious sheets of bark that could be worked much like thick rawhide when fresh, but when dry, became the equivalent of plywood.

In the rich, moist bottom lands of eastern North America, which elms prefer, these fast-growing trees attained huge proportions, growing over 100 feet tall, with trunks 10 feet or more in diameter. Elms have a habit of shedding lower branches early in life and of developing upright, vase-like architectures. This results in massive, knot-free lower trunks that were perfect for the harvesting of bark.

The Iroquois and other peoples flattened out sheets of bark in the sun, drilling holes along the edges while it was supple. After a few days of direct sunlight, the “plywood” was ready to lash to a log framework such as an Iroquois longhouse, many of which were over 100 feet long. Early Europeans were surprised to find Iroquois villages having thousands of bushels of corn stored in elm-bark bins and cribs. Fresh elm bark was also folded to make utensils and containers, which held their shape once dry. Even canoes were made from elm bark, although these were heavy and were not intended to portage.

Every spring I peel a small elm, or even a branch, to make rattles, spoons and baskets. Between late spring and mid-summer, elm bark peels with no more effort than skinning a banana. To be sure, that “peel” is heavier, but it lifts off the wood with surprising ease. Elm bark shrinks quite a bit as it dries, but unlike the bark of many other species, doesn’t split.

Supposedly there’s an Elm Street in every town in the U.S. I doubt that’s strictly true, especially in the arid southwest, but American elms were one of the most extensively planted street trees. Their branches arched up and over utility lines, and transformed even the broadest avenues into oases of shade.

In 1928, Dutch elm disease (DED) was found in North America, opening a sad episode in the tree’s history. Spread by two beetles, one native and one introduced, DED is a fungus that plugs xylem tubes, which bring water and nutrients up to the leaves. Where elms grew in unbroken monocultures, as was the case in many towns and cities, DED was able to also spread through natural root grafts. In this way, elm-lined streets became denuded within a few years.

Small to mid-size elms can be found throughout their native range, north to Nova Scotia and south to northern Florida. In the Adirondacks, where soil type rather than climate often limits where elms will grow, isolated stands of elms often see fewer DED infestation cycles. These stands may grow for several decades, reaching good size before succumbing.

Some large old elms can be found in places such as New York City’s Central Park and on the Penn State campus. These old-timers exist thanks to a regimen of systemic fungicide injections and insecticidal sprays (Penn State clears its campus for helicopter spraying of its elms each year).

Since 1983, the Elm Research Institute in Keene, N.H. has promoted the “American Liberty Elms,” some of which have a degree of resistance to DED. Chinese and Siberian elms are very resistant, but neither is close in size or shape to American elm. Hybrids between these and American elm have fair resistance, but still don’t replace the latter.

Although it’s a long shot, it’s possible we’ll again see massive elms like those whose bark once enclosed longhouses. I sure hope we do.

Paul Hetzler is a forester and Cornell Cooperative Extension of St. Lawrence County horticulture and natural resources educator.