Larry Steckel, a University of Tennessee Extension weed specialist in Jackson, likes to compare the growing problem of herbicide-resistant weeds to Americans’ health habits.
You’re going along overweight, smoking and drinking a bit too much beer. In the back of your mind, you know you should change your habits, but you won’t until a health issue, such as a heart attack, serves as a wake-up call.
Well, many growers—particularly those in the Midwest and South who grow Roundup Ready crops—are having a “pigweed heart attack,” to use Steckel’s words.
Some fields may never recover from that pigweed heart attack. But it should serve as a wake-up call to others, including growers of specialty crops, to change their habits and adopt a more herbicide-healthy lifestyle.
That includes scouting before and after herbicide applications; rotating modes of action; using tankmixes that contain different modes of action; using proper adjuvants, nozzle sizes and droplet sizes; rotating crops where applicable; and using mechanical cultivation if possible.
Steckel told his story at BASF and Bayer CropScience media conferences leading up to the recent Commodity Classic in Nashville.
Scattered pockets of glyphosate-resistant weeds have been confirmed in specialty crops throughout the nation.
They include rigid ryegrass in California’s Imperial Valley and northern Sacramento Valley; Italian ryegrass in Oregon filbert orchards; marestail and hairy fleabane in central California; and Palmer amaranth in a handful of Georgia vegetable fields and New Mexico pecan orchards.
But the resistance problem isn’t nearly as widespread as the millions of acres of infested corn, soybean and cotton ground where growers had adopted an herbicide program based almost exclusively on glyphosate.
In a few short years, water hemp in the Midwest and Palmer amaranth in the South have grown so resistant to glyphosate that many growers never harvest their crops. Instead, they take bush hogs or disks to them, Steckel says. Both weeds are members of the pigweed family.
He estimates that Palmer amaranth cost Tennessee growers of field crops $120 million in 2011 alone.
“If you’re doing a scorecard, we’re failing at trying to steward glyphosate,” Steckel says. “We’re running it right off a cliff in many of our areas.”