The Weed Resistance Problem: A Matter Of Billions

To appreciate just how severe the herbicide-resistant weeds problem has become in the U.S., consider this statistic: According to researchers, approximately half of the country’s growers said that hard-to-kill weeds were a “major problem” in their crop fields during the 2013 growing season. In hard numbers, this translated into more than 70 million acres of land infested with herbicide-resistant weeds, a 17% increase from the previous year. Overall, weed scientists now say there are 200 species of weeds with confirmed resistance to one or more widely used herbicides.

According to Damon Palmer, U.S. commercial leader, Enlist, Dow AgroSciences, this uptick in infested acreage is all the more impressive when you consider that the weather conditions in 2013 didn’t necessarily favor weed growth as in prior years. “As you look across the country, there definitely hasn’t been a decrease in the number of acres being affected by herbicide-resistant weeds,” says Palmer. “With all the cooler and wetter conditions that much of the country experienced during 2013, they should have been a little easier to control than in the hotter weather years we’ve been having. But that wasn’t the case and their numbers still increased.”

The toll these herbicide-resistant weeds can have on growers is staggering. Some varieties can reach 8- to 10-feet in height, with strong stems that can damage farm equipment they encounter. Furthermore, some plants can produce hundreds of thousands of seeds, some of which can remain viable in soil for up to 50 years (as in the case of velvetleaf).

Even worse is the impact these weeds have on the crops themselves. According to a 2009-11 study conducted by the University of Minnesota Extension on corn, when a weed reaches a height of 3 to 4 inches (normally when corn is around the V3 to V4 growth stage), the crop loses approximately 12 to 13 bushels per acre within the first week. During the second week the weed is present, this loss increases to 27 to 29 bushels per acre. By their nature, weeds can exhibit a “luxury consumption” of certain crop inputs such as nitrogen. Furthermore, dense infestations of weeds can lead to allelopathy, a suppression of plant growth due to the release of natural-plant derived substances.

For growers, herbicide-resistant weeds have become a costly problem. At the very least, they are being forced to add additional herbicide applications to protect their investments. At worst, some are going back to hiring crews to hand weed their fields. In both cases, estimates University of Wisconsin researcher Vince Davis, this is adding approximately $2 billion to growers’ annual crop production bills.

And this isn’t the only time billions come up when discussing the impact of herbicide-resistant weeds. “Weed resistance is something we all have to deal with in agriculture,” says David Hollinrake, vice president, agricultural commercial operations marketing for Bayer CropScience. “Today, when you consider the losses in crop yields, weeds around the globe eat the food to feed about one billion people.”

How Resistance Starts

By their nature, many weeds have a natural ability to develop resistance. Recently, a computer model was developed by the University of Arkansas that analyzed the evolution of resistance to herbicides using the Mississippi Delta region of eastern Arkansas as its test case. Looking at 1,000 hypothetical rice fields, this model took into account three stages of growth for the crops and extended it over a 30-year period.

The findings from this computer model were eye-opening, to say the least. Based upon the model, if a certain herbicide is used alone in three annual applications, weed resistance can develop in as little as four years. More interestingly, the model showed that if a grower does not stop using a herbicide soon after resistance takes place, resistance can be accelerated for the next herbicide alternative used, even if it provides a different mode of action.

Waterhemp in soybean stubble
According to the latest data, glyphosate-resistant waterhemp has been confirmed in 12 states.

A similar study was conducted by the University of Missouri on one of the major Midwestern weeds to show resistance, waterhemp. According to the latest data, glyphosate-resistant waterhemp has been confirmed in 12 states. More telling, more than two-thirds of the waterhemp population sampled in the state of Missouri was found to be resistant to the popular herbicide.

For the study, the University of Missouri researchers collected waterhemp seed samples from 144 soybean fields in 54 Missouri counties during 2008 and 2009. Based upon their findings, 94% of the glyphosate-resistant waterhemp populations had three aspects in common:

■ Soybeans were the only crop planted in these fields in consecutive years.

■ Glyphosate was the only herbicide used in these fields for three or more years.

■ The fields contained waterhemp showing signs of having survived the previous herbicide application.

“It isn’t herbicides that create herbicide-resistant weeds,” says Dr. Bryan Young, a professor at Southern Illinois University. “Instead, the culprit is how we use herbicides in an overall weed management strategy. To preserve the effectiveness of herbicides, it is imperative that we become better stewards of their use. Minor changes made today can avoid costly problems in the future.”

Palmer pigweed in soybean stubble
A native to the southwestern U.S., Palmer amaranth first started showing signs of herbicide resistance in the late 1980s.

Further south, the problem child of herbicide-resistant weeds is Palmer amaranth (or pigweed, as it sometimes known). A native to the southwestern U.S., Palmer amaranth first started showing signs of herbicide resistance in the late 1980s. According to researchers, the weed showed confirmed resistance to glyphosate in 2006 in Macon County Georgia. Since then, glyphosate-resistant Palmer amaranth — which can produce more than 600,000 seeds per female plant — has spread across 13 states, including Texas, Virginia and Indiana.

Due to its rapid proliferation ability, the cost to control Palmer amaranth for growers has grown considerably over the past few years. In fact, for the cotton industry, herbicide costs for Palmer amaranth control have increased from $23 per acre in 2004 to $100 per acre in 2012.

“The current model simply isn’t sustainable,” says Dr. Stanley Culpepper, a professor in crop and soil science at the University of Georgia. “Growers have gone to war, and they are making progress from a weed management perspective, but not from an economic or environmental perspective. We need to figure out a way to get the same results far more cost-effectively and in a way that better protects our natural resources.”

The Race For Alternatives

Naturally, crop protection product suppliers have been working on the problem of herbicide-resistant weeds for years and several have potential solutions either just ready to enter the marketplace or coming out in time for the 2015 planting season.

For 2014, the options include Cobra from Valent U.S.A. Containing the active ingredient lactofen, Cobra can be used on such problem weeds as Palmer amaranth and waterhemp in soybeans.

Meanwhile, SePRO Corp. and Nichino America have partnered to launch Brake F2 for Palmer amaranth control in cotton. Containing the active ingredients fluridone and fomesafen, Brake 2F has been granted a Section 18 emergency exemption for 2014 in approved counties in Georgia, South Carolina, North Carolina and Tennessee. According to Dr. Tyler Koschnick, vice president of research and regulatory for SePRO, fomesafen requires low moisture for activation, but provides shorter residual control. Meanwhile, fluridone requires more moisture for activation, but has longer residual control. “The combination of the two complementary active ingredients has shown a tremendous advantage with crop safety with growers reporting extended control of up to six to 10 weeks or longer, depending upon soil type and conditions,” says Koschnick.

Then there’s Engenia, described as a “technologically advanced” dicamba formulation by developer BASF. Expected to have its commercial launch for soybeans in 2014, Engenia has demonstrated “effective control of key broadleaf weeds, including glyphosate-resistant Palmer amaranth, waterhemp, marestail and common/giant ragweed,” says Luke Bozeman, technical market manager, BASF.

In 2015, Dow AgroSciences expects to receive approval for its Enlist Weed Control system. A version of 2,4-D using the company’s Colex-D technology, Enlist has achieved greater than 95% control of several glyphosate-resistant weed types, according to Mike Peterson, global biology leader for the Enlist system at Dow. “Herbicides have been shown to be a key part of efficient, sustainable weed management systems that maximize production while preserving soil and water resources,” says Peterson. “It is important to note that herbicide-tolerant crops have enabled great advances in soil conservation and carbon sequestration. Having farmers go back to widespread tillage to control weeds will negate those environmental advances.”

Also expected to hit the market in 2015 is Acuron from Syngenta Crop Protection. Containing four active ingredients including bicyclopyrene, Acuron employs three modes of action to tackle more than 70 broadleaf weeds including Palmer amaranth and waterhemp, says Dr. Gordon Vail, technical product lead for herbicides at the company.

No matter what options are available in the future for combating herbicide-resistant weeds, the Univer­sity of Wisconsin’s Davis says the more, the better. “Di­versification is the most important thing farmers can do to manage these weeds,” he says. “This includes diversification of effective herbicide modes of action, diversified weed management practices and also utilizing non-herbicide control options such as judicious tillage, cleaning equipment of weed seed and diversified crop rotations. Weeds develop resistance more quickly when production systems remain static.”

Topics: , ,

Leave a Reply

One comment on “The Weed Resistance Problem: A Matter Of Billions

Herbicides Stories

Crop InputsMonsanto: Illegal, Improper Use at Root of Drift Problems
July 14, 2017
Monsanto isn’t backing down from the position that its tool — the Roundup Ready Xtend dicamba-tolerant system for soybeans and Read More
Soybean Closeup
Crop InputsMissouri Lifts Dicamba Ban, Issues Stricter Application Parameters
July 14, 2017
The Missouri Department of Agriculture has lifted its barely week-old ban on new dicamba technologies, which have been at the Read More
Crop InputsAs Drift Complaints Snowball, Tennessee Sets New Dicamba Rules
July 13, 2017
Tennessee is the latest state to issue restrictions on dicamba, following snowballing complaints about the herbicide drifting onto neighboring farms Read More
Crop InputsBASF Responds to Dicamba Restrictions
July 12, 2017
BASF published the following statement on July 10 in response to the dicamba bans set in Arkansas and Missouri: By Read More
Trending Articles
Stewardship‘Gonna Fly Now’ with Environmental Respect
July 20, 2017
One of the most memorable moments in movie history occurred in the Academy Award-winning 1976 film “Rocky.” Haven gotten his Read More
StewardshipEnvironmental Respect 2017 Kicks Off Enjoying an American Pastime
July 18, 2017
Following months of planning and scheduling, the 2017 Environmental Respect Awards (ERA) celebration kicked off in fine fashion as more Read More
Soybean Closeup
Crop InputsMissouri Lifts Dicamba Ban, Issues Stricter Application Parameters
July 14, 2017
The Missouri Department of Agriculture has lifted its barely week-old ban on new dicamba technologies, which have been at the Read More
Crop InputsMonsanto Responds to Arkansas, Missouri Dicamba Bans
July 10, 2017
Monsanto, provider of the dicamba-tolerant Roundup Ready Xtend crop system for soybeans and cotton, issued the following statement on Friday, Read More
Retail FacilitiesPCS-Hammond Meets Fertilizer Storage Needs with New Dome Facility
July 8, 2017
The new barrel dome facility at the PCS-Hammond Regional Distribution Center in Hammond, IN, can hold more than 100,000 tons 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
Latest News
ManagementCropLife Retail Week: Dicamba Update and InfoAg Preview
July 21, 2017
Editors Eric Sfiligoj and Paul Schrimpf discuss reports from the field and comments from Monsanto about dicamba drift this season, Read More
Stewardship‘Gonna Fly Now’ with Environmental Respect
July 20, 2017
One of the most memorable moments in movie history occurred in the Academy Award-winning 1976 film “Rocky.” Haven gotten his Read More
StewardshipEnvironmental Respect: Grand Grounds, Posters Parade
July 19, 2017
To celebrate their accomplishments in the area of environmental stewardship, award recipients at the 2017 Environmental Respect week spent much Read More
StewardshipHarden’s Message to ERA Winners: Do Tell Your Good Stor…
July 19, 2017
As the daughter of a peanut farmer, Krysta Harden, Chief Sustainability Officer for DuPont Crop Protection, understands the importance the Read More
StewardshipFarming Smarter Hinges on 4R Best Management Practices
July 18, 2017
Preserving water quality while feeding another 2 billion people by 2050 is the challenge facing North America’s farmers and its Read More
StewardshipEnvironmental Respect 2017 Kicks Off Enjoying an Americ…
July 18, 2017
Following months of planning and scheduling, the 2017 Environmental Respect Awards (ERA) celebration kicked off in fine fashion as more Read More
Soybean Field Sunset
OpinionPicking Partners in the Crop Protection Market
July 17, 2017
Agriculture is a market awash in highs, lows, and everything in between. This is certainly true in the world of Read More
TMX-2050-In-Cab-Display-Launch-Run-Screen
EquipmentGPS Auto Steer: Innovating in a Mature Market
July 17, 2017
In the world of Big IRON, GPS auto steer has closely mirrored the evolutionary path of consumer GPS Navigation systems Read More
MFA-Centralia-MO
Eric SfiligojThe Resilience of Ag Retailers
July 17, 2017
After covering the ag retail market for 17 years, I think one of the most impressive character traits I’ve seen Read More
SERA-meeting
Stewardship4R Event Explores How to Minimize Phosphorus Losses
July 17, 2017
This year the Southern Extension and Research Activity (SERA) – 17; will be meeting in Oregon, OH, from August 14-17. Read More
Students Soybean Field
StewardshipCCA 4R Study Guide Available
July 17, 2017
In June the International Plant Nutrition Institute (IPNI) released the Certified Crop Advisor (CCA) 4R Nutrient Management Specialist (4R NMS) Read More
Soil soybean closeup
FertilizerThe 4Rs and Potassium
July 17, 2017
Are we meeting crop K needs? Using the 4R nutrient stewardship approach of selecting the right source at the right Read More
Soil Young Corn
StewardshipTop 10 Themes from the 2017 4R Nutrient Stewardship Sum…
July 17, 2017
Preserving water quality while feeding another 2 billion people by 2050 is the challenge facing North America’s farmers and its Read More
Soybean Field Sunset
Crop InputsWhich is Better for Soybeans: Fall or Spring Applicatio…
July 17, 2017
There have been many questions about fall versus spring applications of phosphorus (P) and potassium (K) to soybeans, writes Dr. T. Read More
corn-potassium-deficiency-University-of-Minnesota-Extension
Crop InputsRecognizing Potassium Deficiency Symptoms in Crops
July 17, 2017
Some crops exhibit characteristic deficiency symptoms when adequate amounts of K are not available for growth and development, according to Read More
ManagementComplexity in Agriculture: The Rise (and Fall?) of Mons…
July 17, 2017
Sometimes it seems as if the ag world is changing so fast that we can barely keep up with it Read More
Crop InputsMonsanto: Illegal, Improper Use at Root of Drift Proble…
July 14, 2017
Monsanto isn’t backing down from the position that its tool — the Roundup Ready Xtend dicamba-tolerant system for soybeans and Read More
Soybean Closeup
Crop InputsMissouri Lifts Dicamba Ban, Issues Stricter Application…
July 14, 2017
The Missouri Department of Agriculture has lifted its barely week-old ban on new dicamba technologies, which have been at the Read More