Weeding Out Resistance

Pigweed, glyphosate resistanceThe challenge in growing row crops is back. Corn and especially soybeans had almost become a management no-brainer for retailers and their grower-customers, especially with the adoption of glyphosate-resistant crops.

But all that reliance on glyphosate in the majority of U.S. corn and soybean acres has led to resistant and tolerant weeds. The other shoe has dropped, and as these problem weeds — along with the weeds that are resistant or tolerant to other herbicide chemistries — become more widespread, so does the need to keep an eye on them.

How are retailers dealing with this issue? CropLife® magazine talked to some CropLife 100 retailers to get their take on it.

Waterhemp Worries

MFA Inc. services most of Missouri, the state that documented the first case of triple-resistant weeds, so they know a bit about the problem. “We have major resistance issues across the majority of our territory,” says Paul Tracy, MFA’s director of agronomy services. MFA also serves portions of southern Iowa, eastern Kansas, and northern Arkansas, and its growers have encountered weed resistance to glyphosate, ALS (acetolactate synthase), PPO (protoporphyrinogen oxidase), and triazine herbicides. The No. 1 glyphosate-resistant weed in Missouri is waterhemp.

“In the northern part of the state, we’re probably looking at a rough estimate that 75% to 80% of the counties have some glyphosate resistance,” Tracy says. But “probably less than 20%, maybe less than 10%, of the acreage has glyphosate-resistant waterhemp.”

Horseweed, also called marestail, is problematic in southeastern Missouri, while weed resistance is just moving into the southwestern region.

Like many retailers, MFA recommends resistance prevention practices of crop rotation and mode-of-action rotation. “That’s old stuff; we’ve all been preaching it for years and years, but it doesn’t always sink in with growers,” Tracy says.

He surmises that one reason Missouri has more resistance than some other Midwest states is its abundance of continuous soybeans. “In some areas, we have a lot of continuous beans for eight, 10, 12, 15 years in a row,” he says. MFA now tells its growers to rotate to corn for a year or two and use atrazine and/or other corn herbicides to knock out the waterhemp.

MFA chooses to keep the strategy simple for growers, focusing on the use of older and new residual chemistry along with using other herbicide modes of action. “We have always recommended some residuals down with our Roundup Ready corn, and during the last two or three years, we’ve strongly recommended residuals with our Roundup Ready soybeans as well,” Tracy says.

“It is also a way to preserve crop yields if we cannot get across the field in a timely fashion with the first postemergence application of glyphosate,” says Kevin Bradley, University of Missouri Extension weed specialist.

Tracy points out that there are still a lot of fields that glyphosate works very well on. “We’re still going to be promoting glyphosate-tolerant genetics as the base of our weed control program,” he says. “We just have to deal with all these resistant weeds that are coming along.”

Pesky Pigweed

The resistance picture is somewhat different in the South. While mares­tail has been around for a few years, Palmer amaranth-resistant weeds have been building up even more in soybeans and cotton. Also known as pigweed, this resistant population is expected to “explode” this season, according to Ken Smith, University of Arkansas Extension weed specialist. Currently, 19 counties in the state have confirmed glyphosate-resistant Palmer amaranth, and estimates of some level of infestation in Arkansas are in excess of 650,000 acres.

“Farmers have started realizing things are going to have to start being done a little differently,” says Ben Branch, location manager at Ritter Crop Services in Marked Tree, AR. “We have resistant weeds that are popping up in pockets in our area, and we’re having to change our whole plan basically to manage that problem. These weeds didn’t survive thousands of years without being able to change, so they’ve adapted to the glyphosate chemistry.”

Ritter Crop Services’ 12 outlets serve growers in the northeastern quadrant of Arkansas with 10,000 to 15,000 acres of cotton and “tens of thousands of acres of beans,” Branch says. “Just about every farmer here probably has a resistant or tolerant species of pigweed in a field. And if the beans start canopying over a little bit and the herbicide doesn’t just penetrate down to the small pigweed tucked in underneath, just a little bit of Roundup might not kill it. Instead, all it does is just build the resistance up for the next year, for the next population from that plant.”

The retailer’s resolution is to put down residuals, even overlapping residuals and changing the herbicide mode of action as much as possible. “It’s kind of hard to do in cotton and beans, but crop rotation’s a big help,” Branch says. “You can go to milo or corn and use a different form of chemistry on your problem fields.”

They recommend one of Syngenta‘s Dual products — an older chemistry — and Syngenta’s Reflex and Valent U.S.A. Corp.‘s Valor, which are newer. This application would be followed by Roundup as needed.

“The first shot in the crop, we’re definitely talking about putting out some type of Dual product (an S-metolachlor from Syngenta), or some type of meto­lachlor, just to have a double whammy because once you get the weeds up, it’s hard to kill them,” Branch says.

Smith adds that his office recommends using a residual like Valor or Syngenta’s Prefix as a preemergence or preplant application, scout closely for escapes, and treat while small. Or rotate to a LibertyLink soybean program. “We have some very good recommendations for control of pigweed in LibertyLink soybeans,” he says. Including atrazine in the corn program is still providing excellent pigweed control in the state.

Ritter Crop Service’s staff has been sitting down with growers to talk about the process. “Some of them have already grasped the whole process, and they see that’s what they’re going to have to do,” explains Branch. The extra step of spraying weeds when they’re small is much like conventional soybean management, a practice many haven’t used since switching to Roundup Ready crops.

“It’s going to require a little more management,” Branch adds.

Lessons Learned

MFA’s growers have learned to deal with triazine resistance, which preceeded glyphosate resistance. “We still use atrazine on a large percentage of our corn acres,” says Tracy. “Just because we have resistance to a certain chemistry doesn’t mean we’re going to lose that chemistry, it’s just not as effective as it used to be.

“I always use atrazine as an example when people get really, really fearful of resistance with glyphosate,” he adds. “I use that as an example of something that we have resistance to and we’ve learned to deal with. After we hit field after field year after year with ALS chemistries, we got resistance that’s still out there. But some of those ALS products are coming back around as tools to fight glyphosate resistance.”

Some of MFA’s growers will be planting the recently approved Li­bertyLink soybeans, available on a limited basis for 2009. “That does give them another bullet in their gun to fight resistance,” Tracy says. “But the bottom line on this is unless we change modes of actions on herbicides or management practices one way or another, we’ll get resistance no matter what we throw at these weeds; we know that.”

Topics:

Leave a Reply

Herbicides Stories
HerbicidesScouting Key To Next Season’s Soybean Herbicide Program
August 12, 2014
When growing soybeans, growers need to think ahead to stay one step ahead of weeds. That means examining weed threats and evaluating which herbicides work best. Read More
Winter Wheat
HerbicidesArysta Touts Burndown Herbicide For Brome Management In Wheat
June 4, 2014
Arysta LifeScience North America recommends PRE-PARE Burndown Herbicide for effective brome management in winter wheat. Read More
HerbicidesFall Herbicide Applications More Effectively Manage Resistant Italian Ryegrass
May 14, 2014
Field studies show that a fall application of certain herbicides before weed emergence, leads to more successful crop planting and weed control in spring. Read More
Waterhemp in soybean stubble
HerbicidesThe Weed Resistance Problem: A Matter Of Billions
April 1, 2014
Not only is the amount of money being spent to control these yield robbers high, but the toll it has taken on the human population is growing lager by the day. Read More
Top 100 Articles
Milan Kucerak, president/CEO, West Central
CropLife 100West Central Cooperative And Its New President Are A Match Made In Deviation
June 29, 2015
To appreciate just how unique West Central Cooperative is in the world of ag retail, an observer need only consider Read More
Winter Wheat
CropLife 100South Dakota Co-op Member Owners Vote No On Unification
June 26, 2015
The Boards of Directors for North Central Farmers Elevator (NCFE) and Wheat Growers (WG) have announced that member-owners have voted Read More
CropLife 100The Andersons Acquires South Dakota Plant Nutrient Manufacturer Kay-Flo
May 20, 2015
The Andersons, Inc., ranked No. 22 on the CropLife 100, has purchased Kay Flo Industries of North Sioux City, SD. “This Read More
CropLife 100AgGateway’s Barcoding Initiative Progressing Nicely
May 8, 2015
According to legend (or Wikipedia), the first step towards modern bar codes came back in 1948, when Bernard Silver, a Read More
CropLife 100Pinnacle Agriculture Acquires Minnesota Retailer
April 14, 2015
Pinnacle Agriculture Holdings, LLC, ranked No. 6 on the CropLife 100,  has successfully acquired Liebl Ag, LLC in Ada, MN.  Read More
CropLife 100CHS, Aurora Cooperative Complete Fertilizer Storage, Grain Shuttle Loading Facility
April 13, 2015
CHS Inc., the nation’s leading cooperative and ranked No. 5 on the CropLife 100, and Aurora Cooperative (ranked No. 21) Read More
Latest News
Chesapeake Bay
ManagementCourt Decision Protects Chesapeake Bay’s Water, Wildlif…
July 7, 2015
Today, the Third Circuit Court of Appeals upheld the historic clean-up plan for the Chesapeake Bay. Collin O’Mara, president and Read More
Agworld Apple Watch Farm Management
EquipmentAussie Data Management Software Company Making Its Mark…
July 4, 2015
Western-Australia-based Agworld — having fully launched its data management software system stateside last year after a 2013 soft launch — Read More
Topcon AGI-4 on MF Planter
EquipmentAutosteer: Compatibility, Accuracy Remain Top Of Mind
July 3, 2015
The world of automatic steering solutions in agriculture has evolved rapidly in the last few years. From after-market add-ons that Read More
ManagementUnited Suppliers/Land ‘O Lakes Merger & Crop Update
July 2, 2015
CropLife’s Paul Schrimpf and Eric Sfiligoj talk about the reasons behind the United Suppliers/Land ‘O Lakes merger and USDA’s recent Read More
Industry NewsBioSafe Adds To Sales Force
July 2, 2015
BioSafe Systems has announced the hire of two new members for its service team. David Britt recently joined the team Read More
Chesapeake Bay
ManagementChesapeake Bay Clean-Up Gets Renewed Attention
July 2, 2015
The Chesapeake Bay has been called one of the most biologically productive ecosystems in the world. It’s also one of Read More
Measuring Bulk Tanks
ManagementBulk Pesticide Compliance: Top 10 Areas Of Improvement …
July 1, 2015
  In honor of the 33-year run of David Letterman’s Late Show, the American Agronomic Stewardship Alliance (AASA) is happy Read More
Industry NewsArysta North America Hires Midwest Sales Manager
July 1, 2015
Arysta LifeScience North America recently announced the hiring of Brian Battles as the Senior Technical Sales Manager for the Midwest Read More
Farmer on tablet
Eric SfiligojThe Never-Ending Battle Against Modern Agriculture
July 1, 2015
In the world of comic books, the character of Superman often refers to the fight to save the world as Read More
Retail FacilitiesBuilding Up Ag Retail
July 1, 2015
In the oftentimes unpredictable world we live in, it’s nice to know some things can be reliably countered on to Read More
Retail FacilitiesMaple River Grain And Agronomy Phases In Site Developme…
July 1, 2015
Marcus Construction helped Maple River Grain and Agronomy in Casselton, ND, with the design-build of its dry fertilizer, liquid chemical/seed Read More
Retail FacilitiesA&B Welding Builds A New Liquid Terminal Hub For Br…
July 1, 2015
To build its new hub facility, Briggs Crop Nutrients enlisted the help of A&B Welding. The result, an efficient facility Read More
Edon Farmers Co-op
Retail FacilitiesNew Marcus Facility At Edon Farmers Co-op Provides More…
July 1, 2015
Edon Farmers Co-Op in Edon, OH, needed a new facility to consolidate outdated locations. Marcus Construction was able to design Read More
Retail FacilitiesKinder Morgan Expands Its Storage With A New Dome Barre…
July 1, 2015
Kinder Morgan wanted additional covered storage at its Dakota Bulk Terminal on the Mississippi River in St. Paul, MN. With Read More
Retail FacilitiesHeartland Tank Protects Fertilizer From Extreme Cold At…
July 1, 2015
The Arthur Companies in Harvey, ND, enlisted the help of Heartland Tank Companies to develop a new liquid fertilizer facility Read More
The McGregor Co. fertilizer loadout
Retail FacilitiesThe McGregor Co. Partners With Kahler Automation To Cre…
June 30, 2015
Kahler Automation helped The McGregor Co. expand its Clarkston, WA, operation with unstaffed loadout technology that enables customers to pick Read More
Dry and Liquid Plant
Retail FacilitiesKahler Automation Helps CHS Dakota Ag Cooperative Build…
June 30, 2015
CHS Dakota Ag Cooperative in Mooreton, ND, wanted a liquid/dry blender system that could meet the needs of its customers Read More
Crop InputsLand O’Lakes, United Suppliers To Merge Crop Inpu…
June 29, 2015
Land O’Lakes, Inc. and United Suppliers, Inc. of Ames, IA, today announced their intent to merge their crop inputs businesses. Read More