2 elm breeds found that ward off Dutch elm disease

August 14, 1996|By KNIGHT-RIDDER NEWS SERVICE

WASHINGTON -- Once, the American elm was America's tree. Stately and sturdy, it lined the nation's avenues, adorned its parks and shaded its neighborhoods. Then Dutch elm disease struck.

By the millions, the elms began to die. As the disease spread from state to state, thousands of communities witnessed the toll.

Few battles were won against the disease. But there's hope on one front.

Scientists at the U.S. Department of Agriculture have found two new varieties of American elm that resist Dutch elm disease. They are now being grown in nurseries, and in three years they should be ready for sale -- becoming the first disease-tolerant American elms available to the public.

"It's just amazing how many people are responding to this news," said Alden Townsend, a tree geneticist who has devoted 20 years to the search. "A lot of people have been so upset about losing their trees, and this offers some fresh hope."

The news won't rescue the older American elms that are still alive. Most of those survivors will die, tree specialists say. But the new disease-fighters do offer hope that the American elm has a future.

In its heyday early this century, the American elm was a king of the city. It was a tough tree that grew quickly, survived extreme weather and tolerated road salt.

"It used to be that you could go down many streets and the tree branches would touch, like being under an arbor," recalls Norman Warminski, a tree specialist in Kansas.

But the arrival of Dutch elm disease exposed the risks of planting only one kind of tree.

Historians believe Dutch elm disease was accidentally brought into the United States in 1931, in a shipment of logs to Ohio that contained elm bark beetles. The beetles spread the disease, first around Cleveland, then to neighboring states.

Now the entire eastern United States is affected.

Clyde Hunt, a retired USDA plant geneticist, remembers the disease spreading across the country in the 1960s and 1970s.

"In the 1960s it was in Syracuse, and we lost almost 90 percent of our elms in three years," Hunt said.

To find a new and improved elm, Townsend and another USDA scientist, Lawrence Schreiber, began by searching for a needle in a haystack: one tree in 100,000 that naturally resisted the disease. They injected thousands of trees with the Dutch elm disease fungus; most died.

The public tried to help, sending cuttings from lone trees that had survived the epidemic. After being injected, most of the offspring also died.

But the researchers pressed on. Near Springfield, Ohio, the traveling scientists spotted a lone elm tree.

"It looked like it was the sole survivor of a whole bunch of elms in that part of Ohio," Townsend said.

That tree turned out to be the one.

A second tree showed even stronger resistance to the disease. It is a fourth-generation product of decades of USDA tree-screening trials which began in the 1930s. Scientists would select trees to grow, inject them with the fungus, select the best survivors and then repeat the process.

Eventually the offspring of those two American elms will be sold under the patriotic names of New Harmony (the Ohio tree) and Valley Forge. This summer a Valley Forge variety was planted on the lawn of the U.S. Capitol.

The lesson: It's wise to plant different types of trees.

Pub Date: 8/14/96

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