The $120,000,000 pest...and that’s just one state
Perhaps you’re taking the Alfred E. Neuman approach to herbicide-resistant weeds: “What, me worry?” If so, Tennessee farmers can give you 120 million reasons why that won’t work.
Back in 2011, Larry Steckel, University of Tennessee Extension weed specialist, calculated that glyphosate-resistant weeds cost Tennessee soybean production $120 million annually. Here’s how.
Herbicide costs ran $72,000,000. That’s based on a $45-per-acre cost across 1.6 million soybean acres.
Herbicide application tallied $8,000,000. That’s based on $5 costs across the same acre amount.
Weed competition losses cost $40,000,000. That’s assuming 30% of impacted acres lose 17% of 35-bushel-per-acre yields at a $14-per-bushel soybean price.
Ouch. That’s a particularly tough blow from a decade ago. Back then, two postemergence shots of glyphosate and application costs for soybeans tallied around $20 and created television commercial-clean fields.
That’s changed. “The total postemergence era is over, and I don’t think it’s ever coming back,” says Steckel.
Glyphosate resistance first surfaced in 2000, when glyphosate-resistant marestail was found in a Delaware soybean field. By 2004, glyphosate-resistant marestail spread across 500,000 acres. In 2005, the first glyphosate-resistant waterhemp biotype in the Midwest surfaced in Missouri. By 2008, one third of 200 Iowa waterhemp populations surveyed resisted glyphosate.
As bad as this was, it was just a warm-up for Palmer amaranth, the biggest and baddest of herbicide-resistant pigweeds.
“In the South, we are in a mess,” says Ford Baldwin, co-owner of Practical Weed Consultants and retired University of Arkansas Extension weed scientist. “The Roundup Ready technology has been devalued. This is due to a weed with a little bitty seed without a brain that we have trouble controlling.”
So What do you Do?
Mid-South and Southern farms are figuring out how to deal with it through cultural practices like crop rotation, narrow rows, and the use of herbicides that kill weeds in different ways.
If you’re a Midwestern farmer with no resistance problems, you’re in a great position to prevent problems.
“Resistance management is more proactive than reactive,” says Steckel. “If we look back 10 years in Tennessee, using a combination of a preemergence product followed by a post-product would have delayed resistance, and we would not have had this huge seed bank.”
Following are 13 steps you can take to forestall herbicide-resistant weeds.
1. Know Your Enemy
There are plenty of weeds that resist herbicides. Still, two pigweeds are making life tougher for farmers than many others. In the spirit of the movie Dumb and Dumber, here’s a play-by-play of Worse and Worser when it comes to weeds.
Waterhemp’s season-long emergence pattern enables it to exploit even slight canopy openings. It multiplies rapidly in a field; one plant can produce up to 1 million seeds. It also resists multiple herbicide modes of action.