DYERSBURG, Tenn. — For 15 years, Eddie Anderson, a farmer, has been a
strict adherent of no-till agriculture, an environmentally friendly
technique that all but eliminates plowing to curb erosion and the
harmful runoff of fertilizers and pesticides.

But not this year.

On a recent afternoon here, Mr. Anderson watched as tractors
crisscrossed a rolling field — plowing and mixing herbicides into the
soil to kill weeds where soybeans will soon be planted.

Just as the heavy use of antibiotics contributed to the rise of
drug-resistant supergerms, American farmers’ near-ubiquitous use of the
weedkiller Roundup has led to the rapid growth of tenacious new
superweeds.

To fight them, Mr. Anderson and farmers throughout the East, Midwest
and South are being forced to spray fields with more toxic herbicides,
pull weeds by hand and return to more labor-intensive methods like
regular plowing.

“We’re back to where we were 20 years ago,” said Mr. Anderson, who will
plow about one-third of his 3,000 acres of soybean fields this spring,
more than he has in years. “We’re trying to find out what works.”

Farm experts say that such efforts could lead to higher food prices, lower crop yields, rising farm costs and more pollution of land and water.

“It is the single largest threat to production agriculture that we have
ever seen,” said Andrew Wargo III, the president of the Arkansas
Association of Conservation Districts.