New Rye Could Shed Light on Herbicide
Resistance in Weeds
By Kathryn Barry
November 29, 1996
Two new ryegrass lines may bring
scientists closer to understanding how grasses develop genetic resistance to
The new lines, developed by scientists at the
Agricultural Research Service, have high
tolerance to diclofop-methyl, known in the United States by the trade name
Hoelon. This herbicide is registered to control grass weeds in broadleaf and
In western Oregon, ryegrass is not only a major turf and forage crop but
also one of the worst weeds of winter wheat. Weedy wheat fields can produce 40
to 50 percent less grain than uninfested fields. The grass weeds can become
almost completely resistant to diclofop in as little as three years.
Understanding the biological mechanism of resistance would help scientists
develop better controls for this and other grass weeds. The ARS scientists have
already showed that ryegrass chemical resistance is controlled by only
one or two genes.
Studying how resistance developed has been difficult because researchers
have lacked populations of resistant and susceptible plants that were otherwise
identical. Researchers can now make comparisons using the new lines. ARS
scientists developed them from selections from Gulf and Marshall ryegrass
Small quantities of seed of the new lines, ORARHR-G93 and ORARHR-M93, are
available to researchers.
Scientific contact: Reed E. Barker,
National Forage Seed
Production Research Center, ARS-USDA,
Corvallis, Ore., phone (541) 750-8722.