Evidence Showing Threat Posed by Medusahead Grows

An invasive grass called medusahead that already has a grip on about 2 million acres in the West, and is spreading at a rate of about 12% a year, could be extremely nasty if it isn't brought under some semblance of control soon, according to a study to be published February 2011 in the Journal of Arid Environments.

From an economic perspective, that's a concern because medusahead makes the rangeland it invades virtually worthless for grazing. Environmentally, it's harmful in several ways to many animals that contact it or try to eat it; it increases wildfire risk; and it creates monocultures that have very low biodiversity and crowd out numerous native plant and animal species.

• "Field Growth Comparisons of Invasive Alien Annual and Native Perennial Grasses in Monocultures" (contact lead author Seema Mangla, 541-737-8475, for a copy of the full study); Nov. 11, 2010, press release (includes links to B-roll video).

The grass was introduced from the Mediterranean region in the 1880s. It is now documented in 7 western states (CA, ID, MT, NV, OR, UT, WA) and in a zone around the New York City metroplex (CT, NY, PA). There are concerns that it could spread to more than 75 million acres of public land.

The new study, which the authors say is one of the most comprehensive to date, builds on earlier pieces of evidence collected over several decades suggesting that medusahead has substantial biological advantages over many other plants that are growing in areas it has the potential to invade. The researchers, from OregonStateUniversity and the USDA Agricultural Research Service, conclude that medusahead could become even more devastating than cheatgrass, which already blankets about 50 million acres.

Among the starting points for finding out what medusahead threats exist or may exist in your audience area are your local university, if it has a natural resources or agriculture department, or your county extension agent.

• Cooperative Extension System.
• Background information on medusahead.