Supplemental Information for USDA Petition for Nonregulated Status of DAS

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Dow AgroSciences LLC



### Supplemental Information for Petition for Determination of Nonregulated Status for

Herbicide Tolerant DAS

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- 4 Soybe an

Research Demonstrating Reduction in Potential Off

- Target Movement for 2,4

- D Choline and Colex

- D TM 

### Technology as Part of the Enlist TM 

### Weed Control System The undersigned submits this information under 7 CFR 340.6 to support the determination that

the article should not be regulated under 7 CFR 340.

Submitting Compa ny: Dow AgroSciences LLC

Submitted by:

__________________________________

Mark Krieger, Ph.D. Regulatory Leader
Regulatory Sciences & Government Affairs Dow AgroSciences LLC 9330 Zionsville Road Indianapolis, IN 46268 Telephone: (317) 337

- 3458 FAX: (317) 337

- 4649 mkrieger2@dow.com September 8, 2011

TM Colex

- D and Enlist are trademarks of Dow AgroSciences LLC. Components of the Enlist Weed Control System have not yet received regulatory approvals; approvals are pending.Supplemental Information for USDA Petition for Nonregulated Status of DAS

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Dow AgroSciences LLC 

### Summary

Dow AgroSciences (DAS) has submitted a petition to the United States Department of Agriculture (USDA)’s Animal and Plant Health Inspection Service (APHIS) for the determination of nonregulated status for DAS

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- 4 soybean, which provides tolerance to the herbicides 2,4

- dich lorophenoxy acetic acid (2,4

- D) and glufosinate.

This document is being submitted in response to a request for information from USDA

- A PHIS related to the determination of nonregulated status for DAS

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- 4 soybean and provides information pertaining to volatility and spray drift characteristics associated with 2,4

- D choline and the proprietary formulation comprising Colex

- DTM Technology that is part of the EnlistTM Weed Control System.Supplemental Information for USDA Petition for Nonregulated Status of DAS

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Dow AgroSciences LLC 

## Research Demonstrating Reduction in Potential Off

- Target Movement for 2,4

- D Choline and Colex

- D TM 

## Technology as Part of the Enlist TM 

## Weed Control System

Summary Laboratory Studies:

 2,4

- D choline demonstrated ultra

- low volatilization and significantly less damage to sensitive crops placed only inches away when compared to other forms of 2,4

- D

.
 The Colex

- DTM formulation demonstrated a 64% reduction in driftable fines (volume percentage of droplets less than 150 μm) vs. conventional 2,4

- D/glyphosate tank mix at typical use rates.

 Colex

- DTM technology showed significantly less spray drift as compared to a commercial tank mi x in wind tunnel tests using a range of spray nozzle types. For example, using the TeeJet AIXR 11002 air induction , Colex

- DTM technology reduced driftable fines by 20

- fold as compared to the commercial tank mix.
Field Studies:

 Potted cotton plants placed under domes directly over treated soil showed minimal symptoms from 2,4

- D volatility when Colex

- DTM Technology was utilized (5% visual injury in 6 of 20 plants)
, compared to 13% visual injury in 19 of 20 plants treated with 2,4

- D amine, and 65% visual inju ry in all 20 plants treated with 2,4

- D LV ester.

 Quantification of volatilized 2,4

- D from soybean fields showed that calculated loss rates of 2,4

- D choline were much lower that 2,4

- D dimethyl amine and 2,4

- D ethylhexyl ester. The loss rate of 2,4

- D ethylhe xyl ester was as much as two orders of magnitude greater than the 2,4

- D dimethyl amine form . Loss rates of 2,4

- D choline were about 50X less than the 2,4

- D dimethyl amine.

TM Colex

- D and Enlist are trademarks of Dow AgroSciences LLC. Components of the Enlist Weed Control System have not yet received regulatory approvals; approvals are pending.Supplemental Information for USDA Petition for Nonregulated Status of DAS

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Dow AgroSciences LLC
Introduction Dow AgroSciences (DAS) EnlistTM Weed Control System will include a new and innovative herbicide featuring Colex

- DTM Technology. Colex

- D TM Technology includes : 1) the new 2,4

- D choline , which exhibits ultra

- low volatility ; and 2) the latest formulation science , which has displayed significantly reduced potential for spray droplet drift. The new 2,4

- D choline is a quaternary ammonium salt , different from traditional ester or amine forms. The combination of the ultra

- low volatility of 2,4

- D choline and the drift re duction proper ties of the product formulation result in significantly lower potential for off

- target movement and injury to sensitive crops in neighboring fields.
DAS is conducting extensive , state

- of

- the

- art laboratory and field research including work wi th independent, external experts to advance this technology and quantify the improvements offered in reduced off

- target movement. DAS is also engaged in development of novel modeling capabilities to evaluate the behavior of this technology alone and in com bination with various Best Management Practices.

This document summarizes research done to

- date and underway on potential volatility and drift of Colex

- DTM Technology , including control led laboratory observations, field work under real

world conditions an d modeling

. Laboratory research To ensure improvements in potential volatilizatio n and in drift reduction can be examined separately and evaluated under controlled conditions, research is being conducted in the laboratory and is demonstrat ing the benefits offered by the Colex

- DTM Technology. Laboratory volatility studies

If 2,4

- D volatilization losses and movement from the treated areas occur at high enough concentrations for sufficient periods of time, injury to nearby sensitive plants can occ ur. In the laboratory, wheat plants were treated with various forms of 2,4

- D, including the ethylhexylester (EHE), dimethylamine (DMA), and choline form at rates up to 10X the normal application rates, allowed to briefly dry, and then placed in a covered, vented chamber (referred to as a humidome, Figure 1). With temperatures at approximately 104o, air was pulled via a fan across the wheat to closely

- placed tomato ( Rutgers ) and grape ( Carignane ) plants that are known to be highly susceptible to current commercial 2,4

- D forms. Under these optimal conditions for volatility and movement, 2,4

- D choline demonstrated ultra

- low volatilization and significantly less damage to sensitive crops placed only inches away when compared to other forms of 2,4

- D (Figure 1 ). Laboratory drift studies A primary contributor to the magnitude of spray drift is the droplet size distribution of the applied spray

. S maller droplets contribut e a disproportionally larger degree of off

- target spray movement

. The accepted measure of dr ift potential is the percentage of „driftable fines‟ (definedSupplemental Information for USDA Petition for Nonregulated Status of DAS

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Dow AgroSciences LLC as the volume percentage of the droplets less than 150 μm). The Colex

- DTM Technology formulation reduce s the amount of these fines. A Sympatec laser diffraction particle analyzer was used to measure the spray droplet size distribution of commercial 2,4

- D/glyphosate tank mixes compared to that of the Colex

- DTM formulation at typical use rates . Using a typical flat fan nozzle (TeeJet XR8 002), the percent age of these driftable fines was reduced 64% from about 50% (by volume) for the conventional formulation to only 18% with the Colex

- DTM formulation (Figure 2)

. This represents a significant reduction in the potential for droplet drift to ne ighboring fields. This reduction in drift potential was then further confirmed by wind tunnel studies conducted in collaboration with Dr. Andrew Hewitt at the University of Queensland Center for Pesticide Application

. Results comparing a commercial tank mix (Weedar 64 + Round

- up PowerMax) to the Colex

- DTM formulation were obtained in tests using four different nozzles representative of the range of current options for farmers (TeeJet XR 11002 flat fan (XR), Turbo TeeJet 11002 (TT), TeeJet AIXR 11002 air i nduction (AIXR) and Hypro ULD (Hypro)). Spray drift was quantified using nylon strings at 2 and 5 meters downwind from the nozzle to determine the percentage of spray that had drifted that distance. For all nozzles, the volume of material drifted was much lower for the product containing Colex

- DTM Technology (Figure 3). For the XR and AIXR nozzles, this reduction with the Colex

- DTM Technology compared to the commercial tank mix was 50% or greater. Air induction nozzles produce less driftable fines regardles s of the product being sprayed, and when the best of drift

- control nozzle technology (A IX R) was combined with the Colex

- DTM Technology, the volume at 5 meters dropped from 10% for the commercial tank mix formulation with the conventional flat fan XR nozzle to only 0.5% for the Colex

- DTM Technology product , - a 20

- fold reduction in measured drift.

Field research Although the many variable factors cannot be as well controlled in the field as in the lab, field research allows the opportunity to confirm what has been seen in the lab in larger scale tests and under real

- world conditions. In the field, DAS has conducted several field volatility studies with additional studies underway and is also conducting field drift studies. The results are confirming t he significant reductions in off

- target movement potential offered by Colex

- DTM Technology

. Field volatility studies Georgia In 2010, a field volatility study in Georgia comparing various forms of 2,4

- D , including 2,4

- D choline , was conducted by a researcher at the University of Georgia in collaboration with DAS

. On a recently harvested and disked corn field, 90 x 90 ft test plots were treated with 2,4

- D LV ester + Durango (glyphosate) DMA; 2,4

- D amine + Durango DMA; or the premix of 2,4

- DSupplemental Information for USDA Petition for Nonregulated Status of DAS

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Dow AgroSciences LLC

choline + glyphosate DMA at the rate of about 2.24 kg ae /ha of 2,4

- D and glyphosate (2X the typical use rate). After application, volatility directly over treated ground and outside the boundary of the treated plots was measured using cotton plants (5

- 8 leaves) , which are known to be sensitive to 2,4

- D:

 Pots were placed at predetermined distances of 5, 10, 20, 40, 80 and 160 ft at the cardinal and intercardinal directions around the treated area to evaluate movement from the plots.

 Volatility domes (about 3 x 12 ft in size) were put over 20 potted plants placed directly on a single application pass within the plots after treatment to evaluate worst

- case scenarios. Plants were then removed from under the domes after 48 hours. Percent visual cotton injury for all cotton plots as well as the number of plants under each dome expressing injury symptoms were assessed at multiple time periods after application. At 27 days after application, cotton plants out to 160 ft showed injury from volatility of the 2,4

- D LV ester , while only 8

- 10% injury from the 2,4

- D DMA was observed at 10 ft out, and only 1% or less injury at 5 ft with 2,4

- D choline. Under the domes directly over treated soil, all 20 plants showed symptoms with injury greater than 65% for the 2,4

- D LV ester; on ly 19 of the plants showed injury averaging 13% for the 2,4

- D amine, and under these conditions which would maximize the possibility of injury, the 2,4

- D choline showed minimal impact with less than 5% injury and only 6 plants showing any symptoms (Figure 4).

Indiana To quantify actual levels of 2,4

- D which volatilized from treated areas, air sampling studies were conducted on bare soil and soybean fields at two location s in Indiana in 2010. Separate plots were treated with either a commercial 2,4

- D ethylhexyl ester, a commercial 2,4

- D dimethyl amine (DMA), or the new 2,4

- D choline at 2,4

- D equivalent rates of 1, 2 (double rate) and 5 (quadruple rate) lbs/acres for the ester, DMA, and choline forms, respectively. Sorbent

- filled sampling tubes were placed in 8 compass directions at 5 and 10 meters from the field edges and samples collec ted at 4 or 6 and 12 hours after treatment. Employing weather data collected on

- site and the measured air con centrations, the EPA air transport model ISCST was used to back

- calculate the rate of 2,4

- D loss, or flux, from the plots. The resulting calculated loss rates of the ester were as much as two orders of magnitude great er than the DMA form, with the choline being about 50X less than the DMA

. ISCST was further used with the calculated flux profiles to extrapolate concentration multiplied by time magnitudes (CxT) for a 40

- acre treated field more typical of an actual farmer‟s field

. The contour plots developed from this modeling (Figure 5) indicate the reduction in volatility losses with herbicides featuring Colex

- DTM Technology would also be very significant over the larger trea ted area

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Dow AgroSciences LLC Modeling of potential pesticide movement Processes of drift deposition, volatility and air transport are complex and governed by both chemistry and physical laws, and numerical modeling of these processes can be used to examine potential pesticide transport under the near semi

- infinite parameter combinations that can exist in the field. To continually expand the understanding of any potential movement of 2,4

- D from herbicides featuring Colex

- DTM Technology under future use conditions, DAS has invested in the development of a novel, state

- of

- the

- ar t numerical modeling tool. The model input parameters can be determined from data obtained in the laboratory experiments discussed earlier in this paper. These modeling simulations are collaborating that the ultra

- low volatility, low drift and resulting l imited transport of 2,4

- D choline seen in the lab and field studies would also exist in a wide variety of field conditions. In addition to allowing evaluation under differing field conditions, these modeling techniques allow DAS to provide guidance on Best Management Practices for growers to minimize the potential for off

- target movement

.

Conclusions
Colex

- DTM Technology is novel technology that contains 2,4

- D choline , which is different than other forms of 2,4

- D currently available. The differences in the properties of this 2,4

- D choline combined with advancement in the formulation technology, provide ultra

- low volatility and reduced spray droplet drift. The reduction in volati lization has been proven in both the laboratory and field, and has demonstrated significantly reduce d injury to sensitive crops in these studies compared to the current forms of 2,4

- D. Advancements in formulation technology contained in 2,4

- D products with Colex

- DTM Technology are showing a significant reduction in th e finer spray particles found to be most susceptible to drift compared to current, commercial tank mixes. Combining 2,4

- D choline with these formulation advances provides significantly reduced off

target potential, in terms of both volume and distance, to neighboring fields.
DAS is an industry leader and has invest ed heavily in both development of Colex

- DTM Technology and research to understand and quantify the benefits of these technology advanc es . DAS recognizes that improvements in technology are only part of the answer to prevent off

- target movement, and is committed to working with university experts, regulators, and growers to develop and encourage proper applications according to Best Manag ement Practices.Supplemental Information for USDA Petition for Nonregulated Status of DAS

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Dow AgroSciences LLC Figure 1. Humidome showing wheat treated with various forms of 2,4

- D placed under an enclosed and slightly vented chamber next to sensitive tomato and grape plants (air pulled from wheat across sensitive crops from right to left). Graph shows percent visible injury to grapes from various forms of 2,4

- D tested . There was negligible injury from 2,4

- D choline

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Dow AgroSciences LLC 

### Figure 2. Spray pattern distribution using flat fan nozzle measured with a Sympatec GmbH
, laser diffraction particle analyzer showing a 64% reduction in “driftable fines” (those 1 5 0 μm and less in size represented by red line in the figure ) from about 50% (by volume) for the conventional commercial tank mix to only about 18% with the new premix formulation containing Colex

- DTM T echnology (labeled DAS premix).

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Dow AgroSciences LLC



### Figure 3. Percent volume of spray drift of various commercial tank mix formulations containing 2,4

- D and the new formulation with Colex

- DTM (labeled DAS premix) measured at 2 and 5 meters downwind from various common spray nozzles in wind tunnel tests. For all nozzles , the volume of material drifted was much lower for Colex

DTM . Advanced nozzle design, such as AIXR and Hypro add significant drift reduction potential.Supplemental Information for USDA Petition for Nonregulated Status of DAS

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Dow AgroSciences LLC



### Figure 4: Percent visual injury and number of plants with injury for 20 potted cotton plants per treatment placed directly onto the treated field plot in GA with products containing various forms of 2,4

- D and glyphosat e and covered with volatility domes to maximize potential volatility injury. Cotton plants on plots treated with 2,4

- D choline showed significantly fewer plants injured and significantly less injury.Supplemental Information for USDA Petition for Nonregulated Status of DAS

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Dow AgroSciences LLC 

### Figure 5: Actual air sampling data from test sites treated with various commercial forms of 2,4

- D and the new 2,4

- D choline extrapolated using the ISCST model to simulate potential volatility losses (ppb/hr) over a larger 40

- acre treated field . (Note the ppb/hr scal e in each figure is logarithmic).Supplemental Information for USDA Petition for Nonregulated Status of DAS

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Dow AgroSciences LLC