Road maintenance may accidentally spread the seeds of invasive plants, according to Penn State researchers.

"The road graders that are used during these operations can act like a plow, pushing seeds along the road," said Emily Rauschert, senior project associate and applied ecologist in crop and soil sciences in the College of Agricultural Sciences.

"They can pick up seeds of an invasive grass and spread them several orders of magnitude farther than the natural dispersal."

The researchers created a computer simulation based on field experiments that showed how road regrading in the spring could play a role in the rapid spread of Japanese stilt grass — an invasive plant that can grow up to 5 feet tall — in the Rothrock State Forest area. The plant is considered a threat because its dense growth can prevent trees and native plants from growing.

"Initially, this plant wasn't present locally," Rauschert said. "But within 10 years or so foresters noticed that the plant had spread throughout the area."