Resistant Weeds Continue To Confound Control Efforts

In the annals of weed scientists, 2017 will mark a milestone of sorts. This will be the 60th anniversary of the discovery of the first known herbicide-resistant weeds in 1957 — a spreading dayflower found in a Hawaiian sugarcane field and a wild carrot variety found in Ontario, Canada, that both showed resistance to up to five times the normal usage dosage of synthetic auxin herbicides.

In the past six decades since these discoveries, weed scientists have documented more than 250 weed species with some form of herbicide resistance. These span 23 of the known 26 herbicide modes of action and impact 86 different crops across 66 different countries. As a result, the cost of weed control across the nation’s crop fields has tripled in recent years as growers are being forced to employ more herbicides per season, increase application frequency, and spend more on fuel costs to achieve some measure of control.

And although virtually all modes of action herbicides are being impacted by this trend, Dr. David Shaw, a Weed Scientist for Mississippi State University, says glyphosate-resistant weeds are still getting the lion’s share of attention from all parties, since approximately 90% of soybean, corn, cotton, and sugarbeet acres in the U.S. receive glyphosate treatments.

“The sheer size of the crop acreage impacted by glyphosate-resistant weeds has made glyphosate the public face of the pervasive problem of resistance,” says Shaw. “But resistance issues are far broader than a single herbicide and were around long before glyphosate-resistant, genetically-modified crops were even introduced.”

Daniel Waldstein, Technical Marketing Manager for BASF, agrees. “Growers are really desperate for new solutions right now,” says Waldstein. “Glyphosate as a program all by itself is a thing of the past. And it’s never a good time to have a weed in your field because research shows you end up with a 5% yield loss for every 14 days it’s there.”

The Worst Weeds

According to a recent survey conducted by the Weed Sciences Society of America, Palmer amaranth — also known as pigweed — ranked as the No. 1 most troublesome weed to control in the U.S. Other top finishers in the ranking included morningglory, common lambsquarter, waterhemp, and marestail.

Palmer amaranth
Palmer amaranth was voted the most troublesome weed.

According to various ag retailers, the weed control issue is continuing to grow in severity. “I can’t tell you how, wherever I drive across Illinois, Ohio, and into Iowa, there are more weed escapes than I can remember in the past,” says Jeff Bunting, Crop Protection Division Manager for GROWMARK. “So right now, I think that when a farmer’s going to make an investment, they want to make sure they can use the technology, too. Clearly what we’re doing today is not working in so many fields.”

In addition, resistant weeds are continuing to spread into new areas. “Resistant weeds have been continuing their march north,” says Brad Ruden, Director of Technical Service for South Dakota Wheat Growers (SDWG). “We have confirmed resistance, and some fairly high levels of resistance in our kochia pops, waterhemp, and marestail in the Dakotas. If kochia got any size this year, it got extremely difficult to control, certainly with glyphosate alone but also with some of our combination chemistries, too.”

Still, according to Jeff Carpenter, Corn and Soybean Herbicide Portfolio Manager for DuPont Crop Protection, one of the options for growers to control herbicide-resistant weeds is to use multiple modes of action products in their fields. “Growers understand the implications increasing populations of resistant weeds can have on their operations and are becoming more proactive by applying a full range of tools to fight resistance,” says Carpenter. “To make it easier to achieve more complex tank mixes with less mixing and measuring, we have collaborated with growers to develop a number of herbicides with two, three, or more modes of action, each designed to address specific regional weed concerns.”

In other instances, researchers have found altering farming practices can help in herbicide-resistant weed control such as Palmer amaranth. According to one three-year study conducted by the University of Tennessee, the use of cover crops can create an unfavorable environment for weeds by reducing the light and moisture available to germinate seeds, combined with the use of preemergence herbicides such as fluometuron or acetochlor. “While there is no single solution for season-long control of glyphosate-resistant Palmer amaranth, cover crops used early in the growing season in conjunction with preemergence herbicides can help growers diversify their weed management practices to improve sustainability,” says Dr. Larry Steckel, Associate Professor at the University of Tennessee.

Amy Asmus
Amy Asmus

Besides trying new cropping approaches, some ag retailers recommend growers follow common sense practices to combat herbicide-resistant weeds. According to Amy Asmus, Co-Owner of Asmus Farm Supply, grower-customers in Northern Iowa are seeing an increase in the amount of herbicide-resistant Palmer amaranth in their fields. “We recommend our customers avoid driving a vehicle through fields and clean all vehicles after driving into a seeding,” says Asmus. “We also recommend growers remember to clean their boots, shoes, and pants with a stiff brush or scraper before leaving the site.”

New Products In The Mix

There are also several new herbicide products and new cropping systems coming into the market to help combat herbicide-resistant weeds. This includes Scorch from NuFarm, which is designed to control herbicide-resistant kochia, Talinor from Syngenta, which combines bicyclopyrone and bromoxynil to offer control of kochia and Russian thistle, and Elevore from Dow AgroSciences, which contains Arylex active and claims to control marestail, chickweed, and henbit.

In particular in 2016, say observers, volunteer corn in many of the nation’s soybean fields has been a hard-to-control issue for growers. But in April, Wilbur-Ellis Co. introduced Vaquero herbicide. This featured a new clethodim formulation specifically to address this problem.

“Vaquero is the only enhanced 2-pound clethodim product on the market,” says Dick Barrett, National Director of Branded Products for Wilbur-Ellis. “The trails we’ve completed for this product prove it works faster on volunteer corn at lower use rates compared with other formulations.”

Other growers are looking for entire new cropping systems to help in the battle against herbicide-resistant weeds. In fact, according to Jeff Nagel, Agronomist for Ceres LLP, many growers in the company’s territory having difficulty controlling waterhemp and marestail are looking to make a change away from relying solely on Roundup Ready crop/glyphosate platforms. “There is a segment of our farmers that have managed their herbicide programs pretty well using a Roundup Ready platform, but others have really struggled with their weed control this year,” says Nagel. “So there’s definitely a high interest in the dicamba-based Xtend system from Monsanto as well as LibertyLink for 2017.”

Also pending approval, Dow Agro­Sciences will have its Enlist cropping system available for the 2017 growing season. According to Dr. Jonathan Siebert, Enlist Field Sales Leader for Dow, Enlist soybeans and cotton not only offer tolerance to Enlist Duo herbicide — and combination of the company’s new 2,4-D choline and glyphosate — but to glufosinate as well. This will offer growers the option of using three different modes of action to achieve control of such tough-to-kill weeds as Palmer amaranth, marestail, and giant ragweed. “No other soybean and cotton technology offers tolerance to these three important herbicides for postemergence weed control,” says Siebert. “Glufosinate is an effective mode of action on tough weeds, and with Enlist soybeans and Enlist cotton, it could be a key component of growers’ postemergence weed control programs.”

Engenia soybeans
Many growers are anxious to try Engenia soybeans in their fields.

SDWG’s Ruden also foresees benefits to some of the new cropping systems in his part of the country. “One of the primary issues we have in the Northern Plains is that our soils are cold and wet in the spring, and sometimes our preplant window gets to be very small,” he says. “But if we use one of the new products such as Xtend Max or Engenia from BASF, this will allow us to be able to use those products preemergence, right up to planting, which will allow us to be able to start with clean fields and then use our preemergence herbicides that will be required in these systems to be able to do the most effective job that they can do.”

Looking at the herbicide-resistant weeds problem for 2017 and beyond, Ben Kaehler, U.S. Sales Leader for Dow AgroSciences, says growers have grown used to crop protection product companies coming to the rescue. “We as an industry always had something new there to help save the day,” says Kaehler. “But that’s not true anymore.”

Dr. Stanley Culpepper, a Weed Scientist at the University of Georgia, agrees, pointing out the last new type of herbicides, the HPPD-inhibitors, were discovered in the late 1980s. “It would be naïve to think we are going to spray our way out of the resistance problem,” says Culpepper. “It is paramount that we surround these herbicides with diverse weed control methods in order to preserve their usefulness — not sit back and wait for something better to come along.”

Topics:

Leave a Reply

Special Reports Stories

Junge Zone Flower
Retail FacilitiesNorth Central Cooperative Increases Productivity With Junge Zone Automation
June 3, 2017
Since 1979, Junge Control continues to provide highly accurate fluid and dry ingredient measuring, mixing and tracking systems, and the Read More
Corn soil
Crop NutritionBiostimulants Clamor For A Piece Of The Row Crop Market
April 3, 2017
The question these days isn’t who is venturing into biostimulants — it’s who isn’t. Or more to the point: The Read More
Preside CL beans
Crop NutritionBring More Nutrient Boosters On Board
April 3, 2017
Growers are always on the look-out for that silver bullet that boosts yields and offers bang-up return-on-investment. While such products don’t Read More
Craig Houin, R7/Data Innovation Lead, Sunrise Cooperative
Crop NutritionSunrise Cooperative: Using Precision Ag Technology To Enhance Nutrient Stewardship
April 2, 2017
It’s fair to question whether 4R Nutrient Stewardship programs would even exist today without the advent of precision farming technology. Read More
Trending Articles
PrecisionAg Vision Conference
Precision AgPrecisionAg® Vision Conference: Focused on the Future
June 13, 2017
PrecisionAg® is pleased to announce the return of its PrecisionAg Vision Conference, October 10-12, 2017. Based on overwhelmingly positive response Read More
Redbanded-stinkbug-on-soybean-Photo-credit-Thomas-County-Ag
Crop InputsExperts: Mild Winter, Early Planting Will Increase Soybean Insect Threat
June 12, 2017
Higher than average temperatures this past winter affected much of the nation, especially the South and Midwest. The National Centers Read More
Eric SfiligojMonsanto ‘Picks Its Battles’ by Nixing Deere Deal
May 23, 2017
Having been in the trade journalism game since the mid-1980s, I remember several watershed moments during my career. One of Read More
Migrant farm workers
LegislationTrump: Immigration Crackdown Won’t Impact U.S. Agriculture
May 16, 2017
President Donald Trump said he would seek to keep his tough immigration enforcement policies from harming the U.S. farm industry Read More
AGCO Ratliff featured
Eric SfiligojRemembering Robert Ratliff
May 15, 2017
With all the fast-paced happenings in agriculture this spring, with multiple mergers in the works and planting season in full Read More
Case sprayer nozzle closeup
EquipmentSpray Application: A Nozzle Renaissance
May 2, 2017
If you had asked four-decade ag veteran Mark Bartel, President of Wilger Inc., just a few years ago what lay Read More
Latest News
Engenia soybeans
Crop InputsBASF: ‘Closely Monitoring’ Dicamba Situatio…
June 22, 2017
BASF, whose Engenia herbicide is the target of more than 200 drift complaints in Arkansas, emailed the following statement to Read More
ManagementConsolidation Update
June 22, 2017
Editors Paul Schrimpf and Eric Sfiligoj discuss progress on manufacturer consolidation, and another big move for Midwest cooperative Central Valley Read More
Palmer pigweed seedhead in cotton
Crop InputsThreat of Dicamba Ban Looms in Arkansas
June 22, 2017
The Arkansas State Plant Board has rejected a proposed ban on the use of dicamba herbicide, but a procedural error Read More
Potash Agrium
Crop InputsAgrium-PotashCorp to become Nutrien upon Merger Complet…
June 21, 2017
Potash Corporation of Saskatchewan Inc. and Agrium Inc. have announced today that once the anticipated merger transaction closes, the new Read More
Crop InputsMidwestern BioAg Hosts TerraNu Fertilizer Plant Opening…
June 20, 2017
Last Friday, Midwestern BioAg was joined by over 80 local farmers, media and staff to celebrate the grand opening of Read More
Soybean Field
Industry NewsAligned Ag Distributors Names New President
June 19, 2017
Aligned Ag Distributors LLC announced this morning the appointment of Mary Tolke to the position of President/CEO, effective July 1. Read More
ManagementPlotting Corn, AGCO/Asmark’s Applicator Training Center…
June 15, 2017
Editors Paul Schrimpf and Eric Sfiligoj talk about their recent visits to Columbus, OH, and Bloomington, IL, along with an Read More
Seed/BiotechDow AgroSciences Announces Launch of Enlist Corn for 20…
June 14, 2017
Enlist corn will be commercially available in the U.S. for the 2018 growing season. Dow AgroSciences announced the launch today Read More
ASMARK AGCO Applicator Training Center
EmployeesAsmark, AGCO Open Training Center for Beginning Applica…
June 13, 2017
AGCO Corp. and the Asmark Institute have opened a new Applicator Training Center, created in a collaboration between the two Read More
Power to Do More Contest Winners
HerbicidesDow AgroSciences Announces Three Winners in Power to Do…
June 13, 2017
Thousands of votes have been cast and three farmers have been awarded the power to do more with a $10,000 Read More
Frogeye leaf spot
FungicidesStrobilurin-resistant Frogeye Leaf Spot Threat Looms wi…
June 13, 2017
Heavy spring rainfall throughout the South and Midwest delayed planting and created the perfect environment for diseases like frogeye leaf Read More
PrecisionAg Vision Conference
Precision AgPrecisionAg® Vision Conference: Focused on the Future
June 13, 2017
PrecisionAg® is pleased to announce the return of its PrecisionAg Vision Conference, October 10-12, 2017. Based on overwhelmingly positive response Read More
CHS St. Paul, MN fertilizer terminal
LegislationICGA Praises President Trump’s Remarks on Waterwa…
June 12, 2017
Illinois Corn Growers Association President Justin Durdan, a farmer from Utica, issued the following statement regarding President Donald Trump’s comments Read More
Wheat Growers
UncategorizedWheat Growers Names Tracy Linbo as Senior Vice Presiden…
June 12, 2017
Wheat Growers has hired Tracy Linbo as Senior Vice President of Agronomy. Linbo joins Wheat Growers after having served 10 Read More
EquipmentAgTech Summit Aiming High for Modern Farming Solutions
June 12, 2017
THRIVE AgTech, in partnership with SVG Partners and Forbes, is hosting the third annual Forbes AgTech Summit June 28-29 in Read More
Central Valley Ag Randolph, NE
Precision AgLand O’Lakes Invests in EFC Systems
June 12, 2017
Land O’Lakes, Inc. has made a minority equity investment in EFC Systems, Inc., an ERP (Enterprise Resource Planning) and precision Read More
BRANDT
Crop InputsBRANDT Products Approved for Use with New Cropping Syst…
June 12, 2017
BRANDT, a leading manufacturer of specialty products for the agriculture and turf markets, has announced that 11 BRANDT formulations have Read More
Redbanded-stinkbug-on-soybean-Photo-credit-Thomas-County-Ag
Crop InputsExperts: Mild Winter, Early Planting Will Increase Soyb…
June 12, 2017
Higher than average temperatures this past winter affected much of the nation, especially the South and Midwest. The National Centers Read More