Photo by Greg Grieco

News of elm yellows disease, the latest threat to University Park’s American elms, first surfaced more than a year ago when the University announced the disease had arrived in Centre County. Last month, University officials delivered the grim news that the disease has reached some trees on campus and, potentially, threatens all of the hundreds of elms.

While elm yellows disease has been around for several decades, it only arrived in Centre County about two years ago. The first trees found in the State College area were in Walnut Springs Park, about a mile from the University Park campus. Last year, the disease was found in four trees on campus; this year it affects 47 of the nearly 300 American elms on campus. Many of the infected trees are north of campus near Schreyer House, home to Penn State’s president, but some are on central campus as well.

A bacteria-like organism that scientists believe spreads from tree to tree via a tiny insect, the elm leafhopper, causes elm yellows disease. Once the root cells are infected, the disease spreads to the inner bark and prevents the tree from getting proper nutrition. After it is infected, an elm has roughly one year to live before it dies of malnutrition. To date, no effective treatment exists, and diseased trees must be removed.

Photo by Laura Stocker Waldhier

Some of the infected trees have already been removed while others are being monitored to identify more specifically how the disease spreads. Both infected and healthy trees are also being injected with a fluid analogous to an antibiotic to see if treatment can protect uninfected trees and slow the spread of elm yellows.

Despite a massive effort to save the trees, it might not be possible. “There’s a clear possibility that Penn State will have no elms in several years,” said University Vice President Bill Mahon ’94g. Mahon delivered that grim prospect while speaking in front of a diseased elm that was at least 100 years old, located just south of Deike Building. Penn State’s tree crew removed the tree several weeks later.

Photo by Greg Grieco

Superintendent of grounds Jeff Dice ’76a expanded on Mahon’s statement. “All other communities who’ve faced this have lost all of their elms,” Dice said. “Although elm yellows moves slowly between communities, once it’s in a community it spreads quickly. Many communities in the Northeast and Midwest have already had their elm populations decimated by this disease.”

Despite the not-very-encouraging prospects for the existing elms, Dice said Penn State researchers are actively working to determine how to prevent the spread of elm yellows and how to treat affected trees. “But that research might not be finished in time to save Penn State’s elms,” he added.

Even as researchers wrestle with how to stop elm yellows, planning for replanting is already in progress, said Gordon Turow, director of campus planning and design. Part of that planning is to replace the trees with a number of different species, possibly sycamores and oaks since they can reach the stately heights Penn Staters are used to seeing on the malls and streets of campus. “We don’t want to face another situation in 40 to 50 years where a disease attacks one kind of tree,” Turow said.

Roger Williams ’73, ’75g, ’88g, executive director of the Penn State Alumni Association, noted the emotional connection alumni have with the elms and the disappointment they will have over the loss of the elms. But in a nod to the future, Williams, who has visited many college campuses across the nation, said, “Penn State has one of the most beautiful campuses I’ve ever seen, and I know we as a University will do everything possible to preserve that.”

The University has established an interactive Web site to keep the Penn State community informed about ongoing efforts to understand and fight elm yellows disease at http://elmyellows.psu.edu. The site includes a map showing infected trees’ locations.

For more information on the history of the American elms on the University Park campus, read “Penn State’s Elms: Endeared and Enduring.”