CORVALLIS, Ore. A new field study confirms that an invasive weed called medusahead has growth advantages over most other grass species, suggesting it will continue to spread across much of the West, disrupt native ecosystems and make millions of acres of grazing land almost worthless.
The research, by scientists from Oregon State University and the Agricultural Research Service, was one of the most comprehensive studies ever done that compared the "relative growth rate" of this invasive annual grass to that of other competing species in natural field conditions.
It found that medusahead has a faster growth rate, a longer period of growth and produced more total biomass even than cheatgrass another invading species that is a major problem in its own right, but not as devastating as medusahead.
"Medusahead is now spreading at about 12 percent a year over 17 western states," said Seema Mangla, a researcher in the OSU College of Forestry. "Once established, it's very hard to get rid of. It displaces native grasses and even other invasive species that animals can still eat. Unless we do more to stop it, medusahead will take over much of the native grassland in the West.
"This is a devil species," she said.
Research is identifying some other grass species, including crested wheatgrass and Sandberg's bluegrass, that may be able to compete with medusahead, reduce its spread and preserve the grazing value of lands, Mangla said. They are also studying new ways of restoring medusahead-infested areas. But so far, medusahead has received very little attention compared to other threats such as cheatgrass, even though it ultimately poses a far greater threat to ecosystems across the West.
Cheatgrass is a serious problem on more than 50 million acres, Mangla said, but grazing animals can still eat it. The new study makes it clear that cheatgrass and native grasses may all eventually be replaced by medusahead, which elimin
|Contact: Seema Mangla|
Oregon State University