
New Ways to Put Peanut Weeds Down
UnderBy Jan Suszkiw
TIFTON, Ga., Dec. 16--Fierce competition among warring weeds forces many
peanut growers to climb onto a herbicide treadmill. But U.S. Department of Agriculture weed
scientist Carroll Johnson has a new approach: Coax weed seedlings into the open
early, when the pests are most vulnerable, and then rob them of sunlight. Johnson's tests on small plots suggest peanut growers could save an
estimated $12 per acre on weed-killing chemicals by using different farming
practices. "Currently, growers apply up to six different herbicides to keep pace
with competing weed species," said Johnson, with USDA's
Agricultural Research Service in Tifton,
Ga. The weeds vie for sunlight, water and nutrients, all at the expense of the
peanut crop--and the growers. Peanut farmers in Southern coastal plain states such as Georgia, Alabama and
Florida may spend $75 per acre applying herbicides to combat yellow nutsedge,
Texas panicum, Florida beggarweed and other weeds, Johnson said. And the herbicides arent a sure-fire defense. When one weed species is
killed, another, more durable one may sprout in its place, Johnson noted. He's
based at ARS' Nematodes, Weeds and
Crops Research Unit in Tifton. What we're trying to do," he said, "is find the right
combination of cultural practices to radically reduce herbicide use and cut
other production costs. The critical weed-control period is the first 60 days
of the crop's growth. If weeds are managed early on, fewer corrective measures
are needed later." About nine years ago, Johnson began combining different practices in an
integrated approach. One promising tactic is the "stale seedbed."
This means preparing a seedbed roughly 3 weeks before planting. Weed seeds soon
germinate, but tilling the top 3 inches of soil shortly before planting time
kills young weed seedlings before they can emerge. When the crop is planted--in late April to mid-May--it's seeded in rows
narrower than usual. Since the plants then grow closer together, this fosters a
quicker leaf canopy that blocks sunlight from late-season weeds. Peanut seed tops the farmers crop production costs. And Carroll
credits todays vacuum planter technology with enabling farmers to use the
narrow rows without increasing peanut seeding rates. Early planter designs
didnt allow this. Johnson conducted the small-scale studies last spring in cooperation with
University of Georgia scientists Greg
MacDonald, John Baldwin and John Beasley. The 18- by 20-foot experimental plots
were infested with common coastal-plain weeds of peanuts: Florida beggarweed,
yellow nutsedge, pitted morningglory and Florida pusley. The next step, Johnson said, is to see if the results and projected savings
hold up in tests on larger fields. He plans to adapt the strategy to corn, cotton and cucurbits such as
watermelon and cantaloupe, making life miserable for their weedy competitors as
well. Scientific contact: W. Carroll Johnson III,
Nematodes, Weeds and Crops Research Unit, ARS, USDA, Tifton, Ga., phone (912)
386-3172, fax (912) 386-3437,
[email protected] Story contacts Jan R Suszkiw U.S. Department of Agriculture | |