Fate and Efficacy of Metolachlor Granular and Emulsifiable Concentrate Formulations in a Conservation Tillage System

Use of genetically modified cultivars resistant to the herbicide glyphosate (N-phosphonomethylglycine) is strongly associated with conservation-tillage (CsT) management for maize (Zea mays L.), soybean (Glycine max L.), and cotton (Gossypium hirsutum L.) cultivation. Due to the emergence of glyphosa...

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Bibliographic Details
Published in:Journal of agricultural and food chemistry 2010-10, Vol.58 (19), p.10590-10596
Main Authors: Potter, Thomas L, Gerstl, Zev, White, Paul W, Cutts, George S, Webster, Theodore M, Truman, Clint C, Strickland, Timothy C, Bosch, David D
Format: Article
Language:English
Subjects:
Acetamides - administration & dosage
Acetamides - analysis
adverse effects
agricultural runoff
Agriculture - methods
Alginates
Aluminum Silicates
Biological and medical sciences
Chromaffin Granules
conservation tillage
corn
cotton
Crop and Animal Protection Chemistry
crop management
emulsifiable concentrates
Emulsions
environmental fate
Food industries
Fundamental and applied biological sciences. Psychology
Glucuronic Acid
Glycine max
Gossypium - growth & development
Gossypium hirsutum
granules
herbicide residues
Herbicides - administration & dosage
Herbicides - analysis
Hexuronic Acids
leaching
metolachlor
nontarget organisms
pesticide formulations
pesticide persistence
plant damage
rainfall simulation
Soil - analysis
soybeans
strip tillage
weed control
Zea mays
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Summary:Use of genetically modified cultivars resistant to the herbicide glyphosate (N-phosphonomethylglycine) is strongly associated with conservation-tillage (CsT) management for maize (Zea mays L.), soybean (Glycine max L.), and cotton (Gossypium hirsutum L.) cultivation. Due to the emergence of glyphosate-resistant weed biotypes, alternate weed management practices are needed to sustain CsT use. This work focused on metolachlor use (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide) in a CsT system. The fate and efficacy of granular and emulsifiable concentrate (EC) formulations or an EC surrogate were compared for CsT cotton production in the Atlantic Coastal Plain region of southern Georgia (USA). The granular formulation, a clay−alginate polymer, was produced in the authors' laboratory; EC was a commercial product. In field and laboratory dissipations the granular metolachlor exhibited 8-fold greater soil persistence. Rainfall simulation runoff assessments indicated that use of the granular formulation in a common CsT system, strip-tillage (ST), may reduce metolachlor runoff loss when compared to conventional tillage (CT) management or when EC formulations are used in the ST system. Metolachlor leaching assessments using field-deployed lysimeters showed some tillage (ST > CT) and formulation (EC > granular) differences. Overall leaching was generally small when compared to runoff loss. Finally, greenhouse bioassays showed control of two weed species with the granular was greater than or equal to that of the EC formulation; however, the granular formulation suppressed cotton growth to a greater extent. In sum, this metolachlor granular formulation has advantages for CsT cotton production; however, additional research is needed to assess impacts on crop injury.
ISSN:0021-8561
1520-5118
DOI:10.1021/jf102151y