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United States Department of Agriculture

Agricultural Research Service

Title: Increased Control of Erythroxylum Sp. by Glyphosate Utilizing Various Surfactants

Authors
item Collins, Ronald
item Helling, Charles

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 26, 2002
Publication Date: N/A

Interpretive Summary: Coca plants (scientific name Erythroxylum sp.) are the only source of the narcotic drug cocaine. Destroying illicit coca plants with herbicides is an important component of coordinated efforts to reduce the supply of cocaine entering the United States. The widely-available herbicide glyphosate exhibits very little environmental and toxicological risk and currently is the only herbicide used to control coca. Unfortunately, commercial formulations of glyphosate do not control coca consistently. Greenhouse- based research in Maryland and field-based research conducted in Hawaii tested a wide variety of surfactants, to determine if they improved the control of coca, presumably by increasing herbicide penetration into plant tissues. Two surfactant systems were discovered that increased the potency of glyphosate four-fold over standard commercial formulations. As a result, the mixtures of glyphosate applied in Colombia to control coca have been modified and substantially improved.

Technical Abstract: Glyphosate is the only herbicide approved for coca (Erythroxylum coca var. coca and E. novogranatense var. novogranatense) eradication, and by that is important to the elimination of cocaine production. Unfortunately, standard formulations of glyphosate are inconsistent in controlling coca. Greenhouse-based research in Maryland and field-based research in Hawaii, conducted from 1995 to 1997, determined that two nontoxic surfactants, AL-77 {a 1:1 (by vol) mixture of Agri-Dex and Silwet L-77} and Optima, increased the effectiveness of glyphosate on coca four-fold: 1.1 kg ae ha-1 glyphosate + surfactants was equivalent to 4.4 kg ae ha-1 commercial glyphosate without added surfactant, for both species. As a result, the mixtures of glyphosate applied in Colombia to control coca have been modified, and substantially improved.

Last Modified: 11/27/2014
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