WASHINGTON, May 13 (UPI) — U.S. Agriculture Department scientists say using herbicides to sterilize instead of killing weedy grasses might be more economical and environmentally sound.
The USDA’s Agricultural Research Service said exotic annual grasses such as Japanese brome, cheatgrass and medusahead are harming millions of acres of grassland in the western United States. But herbicides used to control the invasive grasses also sometimes damage desirable perennial grasses.
In contrast, when used properly, scientists said growth regulators don’t greatly harm desirable perennial grasses and can control broadleaf weeds in wheat, other crop grasses and on rangelands.
ARS ecologist Matt Rinella and colleagues said they knew when dicamba and other growth regulator herbicides were applied to cereal crops late in their growth stage, just before seed formation, the plants produced far fewer seeds.
The scientists decided to see what occurred on the invasive weed Japanese brome. They found picloram (Tordon) reduced seed production nearly 100 percent when applied at the late growth stage of the weed. Dicamba (Banvel/Clarity) was slightly less effective but still nearly eliminated seed production, while 2,4-D was much less effective.
Rinella said since annual grass seeds only survive in soil a year or two, it should only take one to three years to greatly reduce the soil seed bank of annual weedy grasses without harming perennial grasses.
The research appeared in the journal Invasive Plant Science and Management.
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