Studies were initiated to evaluate absorption, translocation, and distribution of 14C-quinclorac in propanil- and quinclorac-resistant (R-BYG) and -susceptible (S-BYG) barnyardgrass. No differential absorption of 14C-quinclorac was observed between R-BYG and S-BYG, but more 14C remained in the treated leaf of S-BYG (57% of total absorbed) compared with the R-BYG leaf (34% of total absorbed) at 72 h after treatment (HAT). After 12 HAT, 20 and 15% of the amount absorbed had been translocated basipetally by R-BYG and S-BYG, respectively. At 72 HAT, 27 and 17% of the total absorbed 14C had been translocated acropetally by R-BYG and S-BYG, respectively. The levels of 14C above the treated leaf continued to increase throughout the duration of the experiment in R-BYG while levels of 14C above the treated leaf in S-BYG remained relatively constant. Seven percent more of the total absorbed 14C was exuded from roots of R-BYG than S-BYG at 72 HAT. Although differential translocation was observed between R-BYG and S-BYG, it is unclear whether this difference is a cause of quinclorac resistance or an effect of some other physiological process. Further research is needed to determine if differential translocation is due to metabolism or other physiological factors.

Quinclorac drift has been speculated as the cause of injury to tomato crops throughout northeast Arkansas. In this study, we set out to determine whether tomato plant injury and yield reduction were correlated with simulated quinclorac drift. Experiments were carried out at Fayetteville, AR, in 1999 and 2000. Maximum plant injury (visual ratings) was about 20% when plants were treated with one, two, or three quinclorac applications (weekly intervals beginning at first flower) at 0.42 g ai ha−1(0.001 times the normal use rate to simulate drift). Maximum plant injury ranged from 48 to 68% with quinclorac simulated drift treatment of 42 g ha−1. Overall, increasing quinclorac rate and number of applications increased tomato injury. In both years, tomato plant fresh-weight accumulation was not influenced by one, two, or three applications of quinclorac at 0.42 g ha−1compared with the untreated control. In 1999, increasing the rate of quinclorac from 0.42 to 4.2 g ha−1reduced plant fresh-weight accumulation. In 2000, there was no significant difference in plant fresh weight when plants were treated with quinclorac at 2.1 to 4.2 g ha−1. Evaluation of the herbicide rate effect indicated that quinclorac at 0.42 g ha−1did not reduce tomato fruit yield (total weight of edible fruit) compared with the untreated control, but yield decreased as rate increased above 0.42 g ha−1. Increasing the number of applications generally decreased tomato yield, and overall as maximum visual plant injury increased, tomato yield reduction ALSo increased linearly. We conclude that quinclorac at simulated drift rates can adversely affect tomato plant growth and yield.

Release of InformationDow AgroSciences LLC (DAS) is submitting the information in this petition for deregulation to USDA-APHIS as part of the regulatory process. By submitting this information, DAS does not authorize its release to any third party. If USDA receives a Freedom of Information Act request pursuant to 5 U.S.C., § 552 and 7 CFR Part 1 regarding this information, DAS expects that USDA will provide DAS with a copy of the material proposed to be released and the opportunity to object to the release of any information based on appropriate legal grounds (e.g., responsiveness, confidentiality, and/or competitive concerns). DAS understands that a copy of this information may be made available to the public in a reading room and upon individual request as part of a public comment period. Except in accordance with the foregoing, DAS does not authorize the release, publication or other distribution of this information (including website posting) without prior notice and consent from DAS.© 2013 Dow AgroSciences LLC. All Rights Reserved. This document is property of Dow AgroSciences LLC and is for use by the regulatory authority to which it has been submitted, and only in support of actions requested by Dow AgroSciences. All data and information herein must not be used, reproduced or disclosed to third parties for any other purpose without the written consent of Dow AgroSciences. USDA-APHIS Petition for Nonregulated Status of DAS-8191Ø-7 CottonPage 3 of 214 Dow AgroSciences LLC CertificationThe undersigned certifies that, to the best knowledge and belief of the undersigned, this petition includes all information and views on which to base a determination and that it includes all relevant data and information known to the petitioner, unfavorable as well as favorable, associated with DAS-8191Ø-7 cotton. SummaryDow AgroSciences LLC (herein referred to as "DAS") is submitting a Petition for Determination of Nonregulated Status for DAS-8191Ø-7 cotton. DAS requests from USDA Animal and Plant Health Inspection Service (APHIS) that cotton transformation event DAS-8191Ø-7 and any cotton lines derived from crosses between DAS-8191Ø-7 cotton and conventional cotton or biotechnology-derived cotton granted nonregulated status by APHIS, no longer be considered regulated articles under 7 CFR Part 340.DAS has developed transgenic cotton plants containing aad-12 and pat, which confer tolerance to the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and glufosinate. DAS-8191Ø-7 cotton will provide growers with greater flexibility in selection of herbicides for the improved control of economically important weeds; allow an increased application window for effective weed control; and provide an effective weed resistance management solution to the growing incidence of glyphosate resistant weeds.DAS-8191Ø-7 cotton plants have been genetically modified to express aryloxyalkanoate dioxygenase-12 (AAD-12). AAD-12 is an enzyme with an alpha ketoglutarate-dependent dioxygenase activity which results in metabolic inactivation of the herbi...

Quinclorac (3,7-dichloro-8-quinolinecarboxylic acid) is a herbicide commonly used in rice, and its drift has been suspected of causing injury to off-target tomato fields throughout Arkansas. Studies were conducted to evaluate the effects of single and multiple simulated quinclorac drift applications on tomato plant growth and development. Residues extracted from tomato plants treated with 0.42 g of ai ha(-1) were below the detection limit of liquid chromatography-double mass spectrometry (LC-MS/MS) analysis. Quinclorac residue levels and half-lives in tomato tissue increased as the application rate and number of applications increased. From 3 to 72 h after (14)C-quinclorac treatment of plants, most of the absorbed (14)C was retained in the treated leaf, and translocations of (14)C out of the treated leaf of vegetative and flowering tomato plant tissues were similar. Of the (14)C that translocated out of the treated leaf, the greatest movement was acropetally. The flower cluster contained 1% of the total absorbed (14)C, which suggests the potential for quinclorac translocation into tomato fruit. More extensive research will be required to understand the impact that quinclorac may have on tomato production in the area.