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United States Department of Agriculture

Agricultural Research Service

Title: Polymeric Microcapsules of Selected Herbicides: Preparation and Efficacy

Authors
item Dailey Jr, Oliver
item Dowler, Clyde

Submitted to: Journal of Organic Chemistry
Publication Type: Review Article
Publication Acceptance Date: February 1, 1995
Publication Date: N/A

Interpretive Summary: Recently, concern over the contamination of groundwater and surface water by pesticides has mounted. Atrazine, metribuzin, alachlor, metolachlor, and cyanazine are herbicides frequently implicated in groundwater and surface water contamination. In research to develop pesticide formulations that will maintain or increase efficacy on target organisms and that will not adversely impact on the environment, these herbicides were microencapsulated within six different polymers. Herbicidal activity on various weed species were studied under greenhouse conditions. Microcapsules of atrazine, metribuzin, alachlor, and metolachlor prepared from cellulose derivatives were the most effective. Overall, best results were obtained with atrazine formulations, five of which exhibited herbicidal activity superior to a commercial formulation and controlled-release properties for 32 weeks after treatment.

Technical Abstract: Atrazine, metribuzin, alachlor, metolachlor, and cyanazine are herbicides frequently implicated in groundwater contamination. These herbicides were microencapsulated within six different polymers by the solvent evaporation process using two different emulsifiers. Efficacy studies on various weed species were conducted under greenhouse conditions. Overall, nine of the twelve atrazine formulations were at least as effective as a commercial dry flowable formulation and five exhibited superior herbicidal activity and controlled-release properties for 32 weeks after treatment. Five of the twelve metribuzin formulations exhibited controlled release properties, but were not quite as effective as the commercial formulation. The most efficious polymers were cellulose acetate butyrate and ethyl cellulose. Alachlor and metolachlor formulations prepared with cellulose acetate butyrate and ethyl cellulose were comparable (in a few instances superior) to the commercial formulation in activity, whereas those prepared from low and medium molecular weight poly(methyl methacrylate) exhibited little herbicidal activity. In studies of polymeric formulations of atrazine, metribuzin, alachlor, and metolachlor, microcapsules prepared with poly(alpha-methylstyrene) initially exhibited high activity, but activity dropped dramatically after four or eight weeks. However, poly(alpha-methylstyrene) formulations of cyanazine consistently showed the greatest efficacy, comparable to the commercial formulation, along with one ethyl cellulose formulation.

Last Modified: 10/20/2014
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