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.
|Photo by Greg Grieco|
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.
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
|Photo by Laura Stocker Waldhier|
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
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.”
|Photo by Greg Grieco|
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.”