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Feature

Four people planting a tree.

On Arbor Day, volunteers planted 12 hybrid elm trees on the Minnesota State fairgrounds. After the trees are placed in a 2-foot to 30-inch deep hole, dirt is packed into the hole and thick layer of mulch is added over the dirt. A water truck will go around once a week, especially in the summer, to ensure these trees are adequately watered.

Hardy U elms find home at State Fair

By Pauline Oo

April 28, 2006; updated May 1

What's better than a Dutch elm disease-resistant elm tree? In Minnesota, aka the icebox of the United States, an elm tree that's Dutch elm disease-resistant and cold-hardy.

Last Friday, about 80 people turned up at the rain-soaked Minnesota State Fairgrounds to mark Arbor Day, help plant 12 new University of Minnesota field-tested hybrid elm trees, and kick off a fundraising campaign to reforest the fairgrounds with several varieties of disease and stress-resistant elm trees provided by the U.

For the past six years, the University and the Minneapolis Park and Recreation Board (MPRB) have collaborated to identify new elm varieties for use in the Twin Cities metro area. The new varieties--Asiatic elms field-tested locally by a team of University horticultural and forestry researchers--have the potential to replace the more than 200,000 trees in the Twin Cities that have been lost to Dutch elm disease. The MPRB has been controlling this fungus, spread by beetles through the roots, since the late 1970s. Back then, more than 30,000 elms were removed in one year. On the state fairgrounds, only about 80 of the more than 200 elm trees remain since 2002. Most were lost to the disease, as well as to storm damage and stress.

Chad Giblin and Jeff Gilman
University of Minnesota horticultural scientist Chad Giblin and associate professor of horticultural science Jeff Gilman.

The University-donated elm trees were peppered this afternoon in a dozen sites at the corner of Cooper Street and Lee Avenue.

"These trees are hybrid crosses--Japanese elm, elms from China, and Siberian elm--and have already been selected for Dutch elm disease resistance [when we get them]," says Jeff Gilman, associate professor of horticultural science. "We tested them for horticultural characteristics or environment tolerance for Minnesota weather--cold-hardiness, disease resistant, insect resistant, growth rate. Selection of a good tree takes a minimum of 10 to 20 years." The new, nearly 8-feet-tall State Fair trees were each about 10 years old.

The American elm

According to the Minnesota Department of Natural Resources, "the American elm was at one time the most extensively planted shade tree in the United States because it was easily transported, fast growing, tolerant of limb and root pruning, and had an elegant vase shape that made a perfect high canopy over city streets." The trees shaded so many American streets that "Elm Street" is generally believed to be the most common street name in the United States. However, in the early 1930s a fungal infection borne in beetles was arrived in a shipment of lumber from Europe. A Dutch biologist first identified the pathogen, Ophiostoma ulmi, which was deadly to the American elm. The fungus became known as the Dutch elm disease, and the name has stuck over the years.

Gilman says it won't be long before we'll see the hardy hybrids throughout the Twin Cities. The University grows the varieties for a few years, after which it turns them over to the MPRB to plant in Minneapolis parks and on boulevards. The new elms are also suitable for planting in many other areas of the country, including along the East Coast and in most parts of California.

To learn more about the University of Minnesota's hardy elm trees and the Minnesota State Fair Foundation's plan to reforest the state fairgrounds, listen to State Fair Reforesting Effort" on Univeristy of Minnesota Moment.