Challenging Weed Meets its Match in Field Trials
By Jan Suszkiw
December 22, 2009
In Oregon, California and other
western states, infestations of medusahead have marched across rangeland
habitats like the Genghis Khan of grasses. But at the base of Steens Mountain
in southwestern Oregon, a small but stubborn band of defendersdesert
wheatgrass plantings have held fast against the invader, offering hope of
a new, ecologically based approach to controlling it.
Agricultural Research Service (ARS)
Davies is monitoring the Steens Mountain "standoff" as part of a
broader research effort at Burns, Ore., to develop new tools and strategies for
land managers to use in controlling medusahead, Taeniatherum
caput-medusae. This invasive species infests millions of acres there and in
other western states. It has decimated native plant communities, reduced forage
quality, degraded wildlife habitat and caused other harm, according to Davies,
who works at the ARS
and Meadow Forage Management Research Unit in Burns.
He and ARS ecologist
Sheley and range technician
Nafus first established the desert wheatgrass, Agropyron desertorum,
in February 2006 as a dozen 49- by 33-foot bands on the leading edge of a
medusahead infestation near the foothills of Steens Mountain. Beyond the bands
lay undisturbed communities of sagebrush, squirreltail, needlegrass and other
In June 2008, the team measured the density and canopy cover of medusahead
whose seed had managed to spread beyond the desert wheatgrass barriers and
become established in the plant communities. Medusahead spread data also was
collected from a dozen barrier-free sites.
The team's analysis, presented in Oregon
State University's 2009 Field Day Report earlier this year, showed that
native plant communities without the barriers harbored more medusahead than
those with the barriersa difference of more than 40-fold. Davies
attributes the reduction to the ability of wheatgrass to compete for soil
resources and potentially snare wind-blown medusahead seed.
Future research could focus on fine-tuning the approach and ensuring the
compatibility of desert wheatgrass with native speciesits
"protectees." Ideally, the barriers would be integrated with other
measures, including prescribed grazing and judicious use of herbicides.
ARS is the principal intramural scientific research agency of the
U.S. Department of