Managing the Medusahead Weed
July 24, 2007
Aggressive and unruly, the invasive
weed medusahead covers millions of acres in the Pacific Northwest. Fortunately,
new research from Agricultural Research Service (ARS) scientists is helping landowners tame
this pesky weed.
Medusahead is 11 to 15 percent silica--a gritty mineral that wears away at
teeth--compared to the 1 to 3 percent found in most grasses. It rapidly
replaces native plants and significantly reduces the grazing suitability of the
land it overruns.
Most grazing animals find it unpalatable. Animals that try to reach the few
edible plants that aren't edged out by the weed risk injuring themselves on its
spiky awns, the bristly crowns whose sharp spirals give medusahead its
In 2003, ARS ecologist
L. Sheley spearheaded the "Medusahead Challenge," a program
involving about 130 landowners and range managers from the western United
States. Sheley works in ARS'
and Meadow Forage Management Research Unit in Burns, Ore.
Sheley's program teaches participants to recognize the causes underlying
changes within plant communities and plan effective management strategies for
their property. So far, the program has helped establish medusahead prevention
plans for about 150,000 acres in the region. An additional 20,000 acres are
already under management.
In a related study, Sheley is testing several ecological management theories
to see if they can be practically applied to the Great Basin and Columbia
Plateau, where medusahead is a serious problem.
For example, the Burns scientists have studied the consequences of range
restoration techniques such as disking, a management method that involves
slicing into the soil to break up root systems and allow competing vegetation
to thrive. But disking disturbs the soil, creating a nitrogen-rich environment
that could easily be exploited by rapidly growing weeds. The scientists
recommend minimizing soil disturbance and lowering the nitrogen quickly so that
native species can flourish.
Recommendations like this have helped land managers establish
invasion-resistant plant communities in localized areas within the region.
more about the research in the July 2007 issue of Agricultural Research
ARS is the U.S. Department of
Agriculture's chief scientific research agency.