At the 2010 North Central Weed Science Society Annual Meeting and the 2011 Southern Weed 

Science Society Annual Meeting, scientists and researchers from Dow AgroSciences presented 

scientific, equipment, and application methods papers on new technology on the horizon to 

address weed control challenges. Many topics at the meetings related to weed resistance 

and hard-to-control weeds that are threatening the productivity of agriculture, and Dow 

AgroSciences’ information provided an overview of components of the EnlistTM Weed Control 

System, which is currently undergoing regulatory review for approval. 

“Dow AgroSciences has invested substantial resources into developing game-changing 

technology that will provide farmers new options for exceptional weed control and 

management,” said Mark Peterson, global biology team leader at Dow AgroSciences. “During 

the weed science society meetings, we had the opportunity to present to the weed science 

and academic communities and explain the cutting-edge research and development findings 

behind our innovative trait and herbicide technologies.”

Research and development presentations for the Enlist Weed Control System focused on 

volatility, drift, crop tolerance, and overall efficacy and stewardship programs.

Ultra Low Volatility 

To evaluate the volatility potential of 2,4-D choline, a component of the Colex-DTM Technology, 

scientists from Dow AgroSciences used a variety of methods, including complex laboratory 

evaluations and field-level analytical studies. Volatilization describes vapor loss and migration 

of previously applied active ingredient molecules—in other words—movement of herbicide to 

unintended locations after application because the molecules change from a solid or liquid to 

a gas or vapor. 

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Weed Science Society Recap: Key Components 

of New Technology to Address Weed Control 

Challenges Shared with Scientific Community 
“To determine the relative volatility of different 

2,4-D products, including 2,4-D choline among 

others, laboratory test methods such as 

humidome and volatility chamber tests were 

utilized,” explained Dave Ouse, a scientist at Dow 

AgroSciences. “Humidome testing served as a 

worst case scenario and as a reliable method 

to evaluate herbicide volatility in a contained, 

laboratory environment.”

During the humidome tests, 2,4-D tolerant 

crops were sprayed with a high dose of 2,4-D, 

exposing neighboring sensitive broadleaf plants 

to any vapors generated from the treated plants. 

Humidome tests occurred during a 24-hour period 

at 40° C, and then the sensitive plants were moved 

to a greenhouse and their growth was monitored 

for an additional six days. As another research 

method, volatility chambers were used to quantify 

vapor evolution from 2,4-D formulations at 

different levels of humidity and temperature over 

24, 48, 72, and 96 hours.

To validate laboratory results, field studies were 

conducted on large-scale, small-scale, and 

micro-scale plots to generate qualitative and 

quantitative data to measure the volatility of 2,4-D 

choline. Multiple sized plots were used to obtain 

the most comprehensive set of test data and to 

generate meaningful quantification of movement. 

“Compared to other 2,4-D products, 2,4-D choline 

consistently demonstrated significantly lower 

volatility in the humidome and volatility chamber 

tests,” said Ouse. “Additionally, multiple studies 

on all plots—large, small, and micro—demonstrate 

2,4-D choline has ultra low volatility, reducing 

the frequency and severity of injury to non-target 

plants due to volatility.”

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What is the EnlistTM Weed 

Control System?

The EnlistTM Weed Control 

System is a herbicide-tolerant 

trait technology that will 

provide farmers new solutions 

for managing the increasing 

prevalence of glyphosate-resistant 

and other hard-to-control weeds 

in corn, soybeans, and cotton. 

Enlist will sustain the flexibility, 

convenience, and value gained 

from herbicide-tolerant crops by 

partnering with and improving 

the current glyphosate-tolerant 

cropping system. 

Colex-DTM Technology will be 

featured in the Enlist herbicide 

solution. This new herbicide 

technology will utilize 

2,4-D choline, a unique quaternary 

ammonium salt that is different 

from traditional ester or amine 

2,4-D products, as well as 

feature the latest formulation 

science and a proprietary 

manufacturing process. 

Colex-D Technology will provide 

new features while retaining the 

same weed control efficacy and 

favorable environmental profile 

of traditional 2,4-D products. 

These new features will provide 

farmers and applicators a 

herbicide solution with ultra low 

volatility, minimized potential for 

physical drift, decreased odor, and 

improved handling characteristics, 

improving non-target crop and 

environmental safety.
Minimized Potential for Drift

In addition to volatilization, the other potential contributor to off-target movement that 

needs to be addressed in weed management is spray drift. Different from volatilization, 

drift is the physical movement of spray droplets immediately following application and is a 

function of spray droplet size.

“Nozzle type and application parameters, such as pressure and speed, have major effects on 

drift,” said Steve Wilson, Ph.D., a scientist at Dow AgroSciences. “Tank mix composition and 

formulation properties are also significant since they affect particle size distribution and the 

amount of very small spray droplets that are the primary contributors to drift.” 

 

To demonstrate the effectiveness of the new anti-drift technology in Colex-D Technology, 

cutting-edge wind tunnel research was conducted at the University of Queensland Center for 

Pesticide Application and Safety in Australia. The research compared traditional tank mixes of 

glyphosate and 2,4-D to Dow AgroSciences’ new Colex-D Technology which will be featured in 

the herbicide solution for the Enlist Weed Control System. 

“Our new technology was found to be quite effective at reducing drift for a variety of nozzles 

that were tested,” said Wilson. “Even with low drift nozzle designs, such as induction nozzles, 

significant additional drift reduction was found with our formulation.”

Improved Tolerance and Efficacy 

Tolerance was assessed on the basis of overall crop injury, including growth inhibition, leaning 

and several other factors, as explained by Eric Scherder, a scientist at Dow AgroSciences.

“Crop tolerance studies conclude the new traits will exhibit robust tolerance to 2,4-D choline 

alone or in combination with glyphosate, providing exceptional crop tolerance and safety,” 

said Scherder.

Efficacy was assessed on the basis of percentage of visual weed control, as tested on weeds 

which were generally four-to-six inches tall.

“Weed efficacy studies conclude that the new herbicide products in development by Dow 

AgroSciences will provide an exceptional level of weed control equal to the current amine 

formation used today,” said Scherder. 

Stewardship

Dow AgroSciences is developing a comprehensive stewardship program to promote 

responsible use and sustain long-term future performance of trait and herbicide technologies.

“Dow AgroSciences is committed to stewardship of its new weed control system,” said Kirk 

Dietz, global product leader, agrochemicals, at Dow AgroSciences. “The stewardship program 

was developed to promote integrated trait and herbicide solutions.”

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The stewardship program in development will be comprised of comprehensive product use 

guidelines, grower agreements, education and training, and compliance monitoring to 

ensure the technology is used responsibly and is in compliance with state and federal 

regulatory requirements. 

Dow AgroSciences is encouraging continued dialogue between the company and key 

stakeholders regarding latest research, innovations, and best management practices. The 

company is committed to providing distributors, retailers, growers, and applicators with 

comprehensive stewardship guidance for deploying the Enlist Weed Control System when it 

is approved for use.

“Patents for the new technologies have been submitted in major crop growing countries 

around the world,” added Dietz. “Regulatory submissions for the trait and herbicide 

technologies have also been made to relevant government authorities.” 

Farmers are becoming overwhelmed by weeds. The list of resistant and hard-to-control 

weeds has grown substantially during the past decade — resulting in an evolving landscape 

of increasingly challenging weeds. Dow AgroSciences is developing the Enlist Weed Control 

System to help farmers manage resistant and hard-to-control weeds. Enlist will introduce 

a more effective combination of herbicides, traits in elite genetics, and comprehensive 

stewardship programs. This system will give farmers the clean fields that are necessary to 

deliver top yields, while maintaining industry-preferred farming practices.

Presenters and co-authors included the following scientists and researchers from Dow AgroSciences in Indianapolis, Indiana: A.A. Ahmed; N.M. 

Carranza; K. Dietz; S.C. Ditmarsen; B. Downer; A.T. Ellis; J.M. Ellis; S.M. Ferguson; C.A. Gallup; J.M. Gifford; R.L. Hamm; P.L. Havens; D.E Hillger; 

B.W. Hopkins; J.A. Huff; C.J. Jennings; T. Jones-Jefferson; B.D. Olson; D.G. Ouse; K. Qin; J.S. Richburg; D.C. Ruen; E.F. Scherder; M.E. Schultz; D.M. 

Simpson; N.A. Spomer; J. Stautz; G.R. Tofoli; and S.L. Wilson. 

Enlist Weed Control System was announced as the global brand name for Dow AgroSciences herbicide tolerant trait technology on March 2, 2011. 

TMEnlist is a trademark of Dow AgroSciences LLC. Components of the Enlist Weed Control System have not yet received regulatory approvals; approvals 

are pending. The information provided here is not an offer for sale. ©2011 Dow AgroSciences LLC

M26401003 (06/11) FH010-42296

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