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Pigweed War Reaches Beyond Fields

Resistant weed sprays carry runoff consequences

When Jason Smith was a boy in the 1980s, a farmer could buy a seemingly endless variety of brush hog blades. Everyone he knew mowed field edges and had a ditch bank mower. Broad spectrum herbicides were available at a high dollar, but when Roundup Ready arrived, the turn row game was flipped on its head. Areas once mowed became spray zones as glyphosate prices dropped and pushed brush hogs deeper into the farm shed.

On many farming operations, mowing has given way to high-powered pre-emergents to kill vegetation, but bald ditches might spawn a regulatory leviathan. Silt gathering in the bottom of ditches and canals, eroded turn rows, washed out roads and hammered PTO ditches are caught in a vicious spray cycle of unintended consequences with no simple fix.

“Spray more and more to fight weeds? It’s going to have to stop at some point. We’ve got sediment getting in our waterways and fertilizer coming out of our fields,” Smith says. “Farmers, for the most part, are doing what the experts are telling them and taking a ‘zero tolerance’ approach to pigweed, but it also includes killing everything else.”

Smith farms 3,000 acres in Watson, Ark., and is the inspector of the Cypress Creek Drainage District (CCDD), which empties Desha and Chicot Counties and is the largest district in Arkansas. The CCDD canals start small but can reach 120'-wide halfway across Desha County, and they drain almost 600,000 acres impounded by the Arkansas and Mississippi river levees. Because of the fight against resistant Palmer amaranth, higher than normal sediment levels are eroding into the CCDD canal system and funneling into the Mississippi River, Smith adds. “This never used to happen in this degree,” he says. “Because of the amount and efficiency of the pre-emerge herbicides used today, we don’t have perennials in winter to hold down dirt and it’s literally washing out the bottom of our fields.”

With the incessant swirl over Clean Water Act (CWA) legislation and the threat of government intervention, Smith is ringing an alarm bell because many farmers don’t understand the volume of material coming off their fields. “And it’s getting worse because of pigweed,” he adds. Smith is adamant: Inaction and neglect are far more costly in the long term. 

“Lots of farmers think runoff, EPA and NPDES are just part of a sound bite related to a livestock pond or the Gulf of Mexico,” Smith says. “What about the entire drainage network? From what I see, we do have a problem and we can fix it ourselves without the government having to step in, but we’re running out of time.”

Often chemicals sprayed on turn rows and ditch banks are off-label or not set at field rates. If nutrient runoff regulations are mandated, Smith fears farmers will be caught in the crosshairs. “We’d be done. Anywhere with a big water network would get special government attention. The ‘I can do what I want’ attitude will make us pay a collective price,” he says.

Before the era of precision land leveling and brown turn rows, the ground had protection: crops, grass or weeds. Today, a manicured show farm appears perfect and bare—until a big rain skins sediment from the turn rows, flowing to ditches, canals and rivers. Bald might be beautiful, but it’s not sustainable.  

Take a given 120-acre field: Only 15 years back, it might have drained off five different sides and had a slough running through the center. Water took a long time to run off. Now, with precision leveling, fields have quicker drainage and canal flows, but most drainage districts haven’t adapted.

Smith doesn’t shy away from practical remedies to runoff and offers a tiny amount of wheat on a 2,500-acre farm as an example: Sow 40 acres of wheat and save the seed at cutting. In the fall, after harvest, sow half a bushel of wheat on problem fields and make two passes on the bottom end beside the PTO ditch. Sow turn rows and drainage ditches in wheat for the winter. “A week’s work would bring a tremendous reduction in runoff,” he says.

What about fall work to get ground ready for minimal or no-till in spring? Working a field to bare dirt and bedding up before the colder months isn’t necessarily helpful. “Continuous rain over the winter beats down on exposed ground. Fall prep may look good on paper but sediment is pouring off the fields. We need residue just like other parts of the country,” Smith says

“You might say the road to regulation is paved with good intentions,” says Dan Prevost, conservationist with Delta Farmers Advocating Resource Management (FARM). “Look north to Iowa and the Des Moines Water Works (DMWW) controversy. Iowa is leading the way for nutrient reductions in the Midwest, but is it enough? Those drainage districts involved may still be on the hook.”

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 A bare turn row dipping into a ditch of pigweed  shows stark runoff patterns.

If the DMWW successfully sues drainage districts in three Iowa counties due to high levels of nitrates entering the Raccoon River, the court ruling could rip open the legal door on a host of lawsuits and foreshadow the upending of the CWA. Delta FARM was formed in 1998 by producers concerned over the looming problems associated with nutrient and sediment runoff. In 2008, Delta FARM, along with the Mississippi Department of Environmental Quality and a host of other partners, developed a nutrient reduction strategy for the region. “We’re trying to stay ahead of regulation,” Prevost says. “In Florida, Iowa, Maryland and other states, increased regulation is becoming a reality.”

Prevost suggests farmers implement conservation practices in problem areas. “Start with lighter soils on sandy, higher ground. Just begin with a field or two and try a cover crop in winter. Runoff, compaction and drainage are likely to all get a major boost,” Prevost says.

Steve Stevens grows cotton, corn and soybeans in Desha County, Ark., and participates in the Arkansas Discovery Farm Program, measuring water quality and implementing conservation practices. 

Ideally, a Bermuda grass turn row chokes out pigweed but it can get pulled into fields and become an issue. Stevens sprays an MSMA and diuron combination on Bermuda turn rows to kill weeds yet protect the grass. He is careful not to expose turn row and ditch weeds to the same chemical packages as his crop fields.

Overall, Stevens emphasizes the efficiency of a cereal rye cover in the fall: “I’m talking turn rows and everything. The cereal rye does an amazing job of laying down and forming a mat to help with pigweed suppression. That’s probably where we’re going in the future.”

Stevens is trialing cereal rye on his Discovery Farm fields. In addition to runoff control and pigweed suppression, cereal rye has made a difference in irrigation efficacy. Prior to the cover, Stevens had difficulty getting water deep enough for moisture probe registration, but the cereal rye dramatically improved moisture penetration. 

He’s also pumping less water through furrow irrigation with the PHAUCET (Pipe Hole and Universal Crown Evaluation Tool) program and Delta Plastics’ Pipe Planner app. “These tools may reduce irrigation runoff by 30% to 50% and thereby impact sediment loss, depending on grower and field,” he says.

Real solutions are waiting, but the clock is rolling, Smith says. “People have got pigweed blinders on. They see pigweed right in front and they’re worried about spending extra money. Meanwhile, there’s a runoff problem creeping around behind.” 

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