Weed Control with Starch-Encapsulated Alachlor, Metolachlor, and Atrazine

Buhler, Douglas D.; Schreiber, M. M.; Koskinen, William C.

doi:10.1017/s0890037x0003877x

Cited by 14 publications

(11 citation statements)

References 10 publications

(22 reference statements)

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“…Starch-encapsulated and emulsifiable concentrate (EC) formulations of metolachlor gave similar weed control at low weed densities (122 total plants m −2 ), whereas less weed control was observed with starch encapsulation than with EC formulation at a high weed density (Buhler et al 1994). Organoclay formulations of metolachlor gave excellent weed control for a long period (El-Nahhal et al 1999a).…”

Section: Introductionmentioning

confidence: 99%

Leaching behavior of metolachlor in soil

El‐Nahhal¹

2004

Journal of Environmental Engineering and Science

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This work estimated the leaching behavior of metolachlor from montmorillonite-based and commercial emulsifiable concentrate (EC) formulations in soil columns and field plots by using bioassay and chemical techniques. A montmorillonite-based formulation of metolachlor was prepared by adsorbing metolachlor to montmorillonitebenzyltrimethylammonium (BTMA) complex from aqueous solution. Bioassay and gas chromatography (GC) techniques detected high metolachlor concentrations in the top soil layers (0-9 cm) in soil columns and field plots sprayed with montmorillonite-BTMA-metolachlor complex. These results were also evident by severe growth inhibition restricted to the top soil layers (0-9 cm) and normal growth at deeper layers in soil columns and field plots. A wider range of metolachlor concentrations were detected in soil layers in columns treated with EC formulation in both soil columns and field plots. Relatively higher metolachlor concentrations were detected in the soil layers in field plots than in soil columns. A bioassay technique was a more sensitive tool than chemical technique and detected diluted concentration of metolachlor at deeper layers. The different leaching behavior of metolachlor applied as montmorillonite-BTMA complex is due to the adsorption capacity of montmorillonite-BTMA complex.Résumé : Ce travail estime la lixiviation du métolachlore de formulations à base de montmorillonite et de concentré émulsionnable industriel dans les colonnes de sols et des parcelles expérimentales en utilisant des techniques chimiques et des essais biologiques. Une formulation de métolachlore à base de montmorillonite a été préparée en adsorbant le métolachlore sur un complexe de montmorillonite-benzyltriméthylammonium (BTMA) dans une solution aqueuse. Les essais biologiques et les techniques de chromatographie en phase gazeuse ont détecté de fortes concentrations de métolachlore dans les couches de sol supérieures (0-9 cm) dans les colonnes de sol et les parcelles expérimentales parsemées avec un complexe montmorillonite-BTMA-métolachlore. Ces résultats étaient également évidents par la grave inhibition de croissance dans les couches de sol supérieures (0-9 cm) et la croissance normale dans les couches plus profondes des colonnes de sol et des parcelles expérimentales. Une plus grande plage de concentrations de métolachlore a été détectée dans les couches de sol des colonnes traitées avec une formulation de concentré émulsionnable. Des concentrations relativement plus élevées de métolachlore ont été détectées dans les couches de sol des parcelles expérimentales que dans celles des colonnes de sol. L'essai biologique s'est avéré être une technique plus sensible que la technique chimique et a permis de détecter une concentration diluée de métolachlore dans les couches plus profondes. Le différent comportement de lixiviation du métolachlore sous forme du composé d'addition montmorillonite-BTMA relève de la capacité d'adsorption de ce composé d'addition.

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Section: Introductionmentioning

confidence: 99%

Leaching behavior of metolachlor in soil

El‐Nahhal¹

2004

Journal of Environmental Engineering and Science

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“…21 Weed control ef®cacy was similar with both starch-encapsulated and commercial formulations of metolachlor at low weed densities (122 total plants m À2 ), but less ef®cacy was observed with starch encapsulation than with the commercial formulation at a high weed density (740 plants m À2 ). 22 Our approach was to achieve slow release of herbicide molecules by adsorbing them on clay minerals, which are natural components of soils. The adsorption of organic molecules to clays has been extensively studied.…”

Section: Introductionmentioning

confidence: 99%

Movement of metolachlor in soil: effect of new organo-clay formulations

et al. 1999

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The use of commercially available formulations of metolachlor has resulted in its leaching and migration to water sources. Formulations of metolachlor designed to reduce its leaching in soil have been prepared by adding the herbicide dissolved in an organic solvent or in water to organo-clay complexes. Best formulations were made when the organo-clay complex was formed by adsorbing the monovalent organic cations benzyltrimethylammonium (BTMA) or benzyltriethylammonium (BTEA) onto sodium montmorillonite (Mont) at 0.5 or 0.8 mole kg À1 clay. Adsorption of metolachlor to organo-clays followed the sequence Mont-BTMA 0.5 b Mont-BTMA 0.8 b Mont-BTEA 0.8 b Mont-BTEA 0.5 b Mont. Fourier transform infrared (FTIR) analysis demonstrated the occurrence of shifts of several peaks of adsorbed metolachlor relative to the free herbicide, indicating the existence of strong interactions between metolachlor molecules and the organo-clay surface. Leaching studies employing organo-clay and commercial formulations were carried out under greenhouse and ®eld conditions. Metolachlor applied as organo-clay formulations leached less than the commercial formulation. Organo-clay formulations prepared by adding the herbicide as a water solution showed less leaching in the soil pro®le than those made by using organic solvent. Under greenhouse conditions, the herbicidal activity of organo-clay formulations was similar to that of the commercial one. Under ®eld conditions, leaching from Mont-BTMA 0.5-metolachlor was less than that from the commercial formulation, demonstrating the environmental and agricultural advantages of the organo-clay formulations of metolachlor.

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“…Starch-encapsulated formulations of alachlor, atrazine, and me-tolaehlor controlled annual grass and small-seeded broadleaf species equal or superior to commercial formulations, but encap sulation reduced control of velvetleaf (Abutilon theophrasti Medik.) with atrazine (3). In a summary of research conducted in six states in the midwestem U.S. over 3 yr, Schreiber et al (14) concluded that weed control with starch-encapsulated alachlor, atrazine, and metolachlor was influenced by weed species, soil type and moisture, and granule size.…”

Section: Introductionmentioning

confidence: 99%

Dissipation of Alachlor, Metolachlor, and Atrazine from Starch-Encapsulated Formulations in a Sandy Loam Soil

Buhler¹,

Koskinen

Schreiber

et al. 1994

Weed sci.

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Research was conducted to determine the effect of starch encapsulation on soil dissipation and weed control with alachlor, metolachlor, and atrazine on an Estherville sandy loam in the field. Starch encapsulation increased persistence of alachlor in the surface 15 cm of soil compared to the emulsifiable concentrate formulation during the first 60 d after treatment More alachlor was detected 30 to 75 cm deep with emulsifiable concentrate than the starch-encapsulated formulation 30 d after treatment. Little alachlor was detected below 15 cm thereafter. Starch encapsulation also increased persistence of metolachlor in the surface 15 cm, but reduced concentrations at 15 to 30 cm compared to the emulsifiable concentrate 30 d after treatment. By 120 and 340 d after treatment, metolachlor concentrations at 15 to 30 cm were greater with starch-encapsulated than emulsifiable concentrate formulation. Starch encapsulation greatly increased atrazine persistence in the surface 15 cm compared to the dry flowable formulation. Although encapsulation increased atrazine concentration in the surface 15 cm, it reduced the concentration below 15 cm compared to the dry flowable formulation 30 and 60 d after treatment However, by 120 and 340 d after treatment, starch encapsulation often resulted in greater atrazine concentrations below 15 cm than the dry flowable formulation. Control of green foxtail and redroot pigweed with starch-encapsulated herbicides was similar or superior to the commercial formulations.

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Weed Control with Starch-Encapsulated Alachlor, Metolachlor, and Atrazine

Cited by 14 publications

References 10 publications

Leaching behavior of metolachlor in soil

Leaching behavior of metolachlor in soil

Movement of metolachlor in soil: effect of new organo-clay formulations

Dissipation of Alachlor, Metolachlor, and Atrazine from Starch-Encapsulated Formulations in a Sandy Loam Soil

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