Price of convenience: EPA's endangered species, weed resistance goals conflict

FARGO -- Cheap is not sustainable. Low commodity prices will tempt farmers to cut back on weed control, but it won't work to rely on a single mode of action for multiple years, said Jason Norsworthy, a University of Arkansas weed scientist, speak...

Jason Norsworthy, a University of Arkansas weed scientist (right) talks about weed resistance challenges in a conference sponsored by Carl Peterson (left) and his Peterson Farms Seed of Horace, N.D. (Forum News Service/Agweek/Mikkel Pates)

FARGO -- Cheap is not sustainable.

Low commodity prices will tempt farmers to cut back on weed control, but it won't work to rely on a single mode of action for multiple years, said Jason Norsworthy, a University of Arkansas weed scientist, speaking recently at a Regional Weed Resistance Conference in Fargo.

"If a weed program lacks diversity, you will quickly develop resistance," Norsworthy said. "And it's nothing specific to the Roundup ready (glyphosate) program."

Farmers need a minimum of two effective modes of herbicide action in a soybean field in a given year, and then perhaps rotate to other modes for different crops the following year, said Norsworthy, who is part of a U.S. Department of Agriculture project that has engaged sociologists and agricultural economists on how to get through to farmers dealing with resistance.

Biological controls -- not chemicals -- likely are the "the future of weed control," but those breakthroughs likely won't come for another 15 to 20 years. Farmers have to be proactive to protect herbicides they have now, and the ones coming through the pipeline.


One of the latest solutions is dicamba, and colleagues have confirmed dicamba resistance in kochia in a greenhouse after only three growth generations.

"Three generations, and it would have been three years in the field," he said.

Seed destructors

The rate of glyphosate-resistant weeds spread continues to rise, Norsworthy said. Looking to 2020, scientists project 164.5 million acres with Roundup resistant weeds, and on the "vast majority of U.S. crop acres, at that point, we've had the loss of the world's greatest herbicide."

Stacked traits -- if overused -- can create stacked resistance, he said. Once a field has resistance to a chemical for a particular weed, that resistance is permanent.

The best strategy for weed control is to create a quick crop canopy that shades the soil surface. The proper weed size for most postemergence herbicides is 2 to 4 inches -- not 6 inches or 12 inches. Spraying larger weeds or shaving application rates to save money expands the population of resistance.

Norsworthy said his own research shows 99 percent of waterhemp and Palmer amaranth weed seed goes through a combine at harvest. "If it goes through that combine, what are we doing with that seed? We're turning around and spreading it across our field," he said. "That's how resistance spreads."


Norsworthy showed photos of the Harrington Seed Destructor, a pull-

behind machine that attaches to a combine to kill weed seeds. Developed by a farmer in Western Australia, the machine employs cage mills, spinning in opposite directions, to crack or pulverized weed seeds, which rot when they fall to the ground and are exposed to moisture.

If brought to the U.S., a seed destructor would likely cost roughly $220,000, Norsworthy said. "I expect within the next five years, when you go and purchase a combine, just like having an opportunity to put GPS or GIS on a combine, you'll have an opportunity to buy an in-the-combine seed destructor" attachment, he said. "I expect those costs to be $50,000 to $75,000."

Norsworthy said the seed destructors could be designed to be removed and refitted onto various machines.

Norsworthy said farmers with 2,000 or 3,000 acres that are spraying herbicides at $10 per acre could calculate the machines are worth the cost.

EPA's paradox

Norsworthy said the federal Environmental Protection Agency -- influenced by activists groups who use lawsuits to enforce the Endangered Species Act -- is in conflict with practices to prevent weed resistance to herbicides.


Last November, the EPA requested the courts revoke the Dow's Enlist Duo product label. "Never before has the EPA gotten involved in herbicide resistance," Norsworthy said. "But I'm going to tell you they are now involved in herbicide resistance. They are extremely bothered, extremely upset over what happened with glyphosate -- world's greatest herbicide. And we have upwards of 100 million acres of resistance in the U.S."

The EPA is interested in "off-target drift," and the Endangered Species Act is trying to protect exposure through increased grassed buffers. "But once you have a buffer, how do you control weeds on that buffer," Norsworthy said. "As weed populations increase, the risk of (herbicide) resistance increases. If we focus on resistance management, we will sacrifice some drift management," he said.

Chemical companies are going to recommend nozzles with "larger and larger droplets" to avoid the drift, but that reduces coverage, which cuts the effectiveness of herbicides, especially on grassy weeds. "The risk of resistance is going to increase as we reduce spray coverage," he said. "This is a perfect scenario for glyphosate-resistant grass to develop."

Going forward, the EPA will include herbicide resistance language on the label -- a first.

Tank-mix police?

"If you spray one of these technologies, and it fails, the (manufacturing) company must go monitor -- must take that sample, where it failed -- collect that sample, monitor that site, report back to the EPA as to whether it's resistant, and work with you to mitigate that potential resistance," he said. "That's never been done before here in the U.S."

The EPA will mandate the use of certain nozzles, but the farmer can't place anything in the tank with the new products (dicamba and 2,4-D products), that nothing can go in the tank unless it's been approved."

That precludes tank mixing with an adjuvant, a liquid fertilizer, an insecticide or another herbicide, unless it's been tested and is listed as approved on the EPA website, he said.

"This becomes very expensive from the company's standpoint," Norsworthy said.

A two-way combination is not compliant if the farmer adds a substance that has not approved, because it changes the spray pattern effectiveness. "Folks, it's going to be complicated, and the days of just throwing any adjuvant in there, or tank-mixing any product, I'm not saying those days are going to be complicated," he said.

Carl Peterson, president of Peterson Farms Seed, which organized the conference, became emotional about the reason for the event. He said farmers, ag chemical producers and seed people have a responsibility to steward technologies so that farmers can continue to produce the food that the world needs.

Related Topics: AGRICULTURE
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