The Penn State Office of Physical Plant (OPP) finished spraying insecticide on elm trees lining the Pattee Mall last week, and officials said students need not worry about the chemicals being used.
Efforts began Tuesday evening with crews spraying from the ground as a part of a two-part procedure, OPP spokesman Paul Ruskin said.
"We used ground application for the bottom half and helicopter application for the top half," Ruskin said.
The spraying is part of an effort to rid the campus's elms of diseases like Dutch Elm Disease and Elm yellows.
Penn State boasts one of the largest elm tree collections in the country. Elm yellows has affected more than 15 percent of the university's over 200 elms.
Preventing the disease has become a priority for OPP because no known cure exists.
The insecticide used is called Astro, commonly referred to as permethrin, a safe and common spray, said Ed Rajotte, professor of entomology and Integrated Pest Management (IPM) coordinator.
Chris Tutolo, public relations officer for Penn State Eco-Action, said the elms are a fundamental part of the campus scenery.
"They're dwindling. It's unfortunate," Tutolo (sophomore-journalism) said. "They're an integral part of Penn State."
Its major component is the same chemical used to treat children for head lice, Ruskin said.
People walking along the mall were well warned about the spraying, despite the chemical's relative harmlessness, Ruskin said.
Signs were posted beforehand warning pedestrians of the spraying. Crew members were also present to give notice to bystanders, Rajotte said.
Rajotte said permethrin is safe because it has low oral, dermal and inhalation toxicity.
"Once the chemical has dried, it becomes much less dangerous to non-target organisms," Rajotte said.
Despite the protective clothing worn by ground crew members during the spraying, Ruskin said students should not be alarmed.
"The handlers were in close contact with the materials," Ruskin said. "The Office of Physical Plant likes to keep them safe even though Astro is not hazardous."
Ruskin said OPP defines Integrated Pest Management as "the coordinated use of pest and environmental information to implement pest control methods that are economically, environmentally, and socially sound."
Pending further exploration, OPP does not plan to spray again during the summer semester unless disease-carrying insects begin to pose a problem, Ruskin said.
