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
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
CropLife 100The Andersons Starts Venture Capital Subsidiary
January 26, 2015
The Andersons has established Maumee Ventures, a venture capital subsidiary designed to foster promising innovations that strategically align with the company’s core businesses. Read More
CropLife 100CHS Partners With Northern Partners Coop On Fertilizer Warehouse
January 21, 2015
In addition, the two companies will form a joint venture to build and operate a grain barge loading facility that will handle corn, soybeans and wheat for export through the CHS terminal at Myrtle Grove, LA. Read More
CropLife 100Wilbur-Ellis Move To Colorado Complete
January 20, 2015
Wilbur-Ellis Co. announces the opening of its new Agribusiness Division location in the Denver, CO, Metro Area. The new facility will host key personnel as the company shifts the base of its Agribusiness operations from California to Colorado. Read More
CropLife 100United Suppliers, McGregor Co., Five Others To Form Aligned Ag Distributors
January 20, 2015
These companies will continue to operate as independently owned and operated businesses, however, their crop protection divisions will now be formally aligned under the umbrella of Aligned Ag Distributors. Read More
CropLife 100Bozeman Named SEEDWAY Chief Operating Officer
January 16, 2015
He succeeds Donald Wertman, who will retire at the end of August 2015 after 40 years with the GROWMARK subsidiary. Read More
CropLife 100Wilbur-Ellis’ Craig Bair Honored For Safety Contributions To Ag Aviation
January 14, 2015
The William O. Marsh Safety Award recognizes significant achievements in safety, safety education or an outstanding operational safety program. Read More
Latest News
ManagementOABA Conference Set To Highlight Trends, Technology And…
January 29, 2015
The third annual Ohio AgriBusiness Association (OABA) Industry Conference is set to take place February 4-5. Read More
FertilizerThe Fertilizer Institute President Jahn Testifies Befor…
January 28, 2015
The committee hearing, "Freight Rail Transportation: Enhancing Safety, Efficiency, and Commerce," looked at challenges facing our nation's freight rail network created by higher demand, rules and regulations and infrastructure needs. Read More
HerbicidesPurdue University Acquires Technology For Herbicide Mol…
January 28, 2015
Protea's LAESI DP-1000 Instrument System will be used in Purdue's College of Agriculture, the Department of Botany and Plant Pathology, for the molecular imaging of herbicide active ingredients and other related compounds to optimize herbicide applications and improve weed management.  Read More
FertilizerH.J. Baker Hires New Crop Peformance Marketing Manager
January 27, 2015
As Marketing Manager for the Crop Performance division, Usman Khalid will work out of H.J. Baker’s global headquarters in Westport, CT, and will drive new initiatives for the division. Read More
CropLife 100The Andersons Starts Venture Capital Subsidiary
January 26, 2015
The Andersons has established Maumee Ventures, a venture capital subsidiary designed to foster promising innovations that strategically align with the company’s core businesses. Read More
Exclusive state-of-the art Stueve Construction designed “Vista View” Elevated Control Room.
Eric Sfiligoj2015 Agricultural Market Read: Mixed
January 26, 2015
The agricultural market could look radically different this year, profit-wise, depending upon which segment you do business in. Read More
Edward Chell Biosafe
Crop InputsBioSafe Systems Names Ed Chell California Territory Man…
January 26, 2015
BioSafe Systems has announced the recent addition of Ed Chell as California Territory Manager for the agrichemical division, supporting the crop protection, water treatment and food safety business segments. Read More
InsecticidesBayer CropScience Introduces Sivanto Insecticide
January 26, 2015
Sivanto precisely targets key damaging pests at multiple insect life stages to prevent damage to plants and help minimize the spread of diseases from insect carriers. Read More
ManagementRetail Collaboration, Communicating Agriculture’s Good …
January 23, 2015
Editors Paul Schrimpf and Eric Sfiligoj discuss the recent creation of Aligned Ag Distributors, and the US Farmers and Ranchers Read More
FertilizerOSU Expert: Toledo Water Crisis A Turning Point For Ohi…
January 23, 2015
The August 2014 water crisis in Toledo, OH, impacted Ohioans’ views of Lake Erie algae problems by increasing the attribution of blame of algae growth on agriculture. Read More
FertilizerH.J. Baker Launching TIGER XP
January 22, 2015
Tiger-Sul introduces this next generation sulphur-bentonite product with a proprietary activator – ensuring farmers have a well-balanced nutrient replacement program. Read More
Crop InputsH.J. Baker Expands China Sales Force
January 21, 2015
Global Agricultural firm H.J. Baker announced that sales veteran Shi Dongshen has joined their Shanghai office in China. This newest hire follows the recent opening of their Lianyungang Sulphur Bentonite Plant. Read More
CropLife 100CHS Partners With Northern Partners Coop On Fertilizer …
January 21, 2015
In addition, the two companies will form a joint venture to build and operate a grain barge loading facility that will handle corn, soybeans and wheat for export through the CHS terminal at Myrtle Grove, LA. Read More
Matt Hopkins5 Bold Predictions For Ag Retail In 2015
January 21, 2015
This past year was filled with ups and downs for the nation’s top ag retailers, but what will 2015 have in store? Read More
SoftwareDeere Launches App Center
January 20, 2015
The John Deere App Center provides users the ability to search and find apps most useful to their business or operations. Read More
Crop InputsNew Syngenta Herbicide Approved In Soybeans, Sunflowers
January 20, 2015
Syngenta will sell BroadAxe XC herbicide in 2015 for use on soybeans, sunflowers and dry peas Read More
CropLife 100Wilbur-Ellis Move To Colorado Complete
January 20, 2015
Wilbur-Ellis Co. announces the opening of its new Agribusiness Division location in the Denver, CO, Metro Area. The new facility will host key personnel as the company shifts the base of its Agribusiness operations from California to Colorado. Read More
Crop InputsNovozymes Sales Figures Up For 2014
January 20, 2015
Novozymes announces its sales growth in 2014 was in line with expectations as sales grew by 7% compared with 2013. Read More