Release Rate of Three Herbicides from Controlled-Release Tablets

Gorski, S. F.; Reiners, Stephen; Ruizzo, Michael A.

doi:10.1017/s0890037x00031936

Cited by 11 publications

(14 citation statements)

References 17 publications

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“…Similar mobility of metolachlor in soil has been reported previously. 41 Formulating metolachlor with montmorillonite without any pre-adsorption with organic cation did not bring about any reduction of leaching compared to that of the commercial formulation. Formulating metolachlor (dissolved in acetone) with clay pre-adsorbed with BTMA at a load of 0.5 mole kg À1 resulted in a signi®cant inhibition of leaching, and with herbicidal activity limited to the top 14 cm (Fig 4).…”

Section: Leaching Studiesmentioning

confidence: 89%

“…These attempts involved the use of starch ecapsulation, 20 and tablet forms. 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.…”

Section: Introductionmentioning

confidence: 84%

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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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Section: Leaching Studiesmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 84%

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

et al. 1999

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“…8,9) The controlled release formulation has an advantage in reducing pesticide losses by leaching, evaporation, degradation, phytotoxicity, and the use and impact of pesticides on the environment. [10][11][12] With controlled release technology, the granular formulation can prolong pesticide effects, as well as increase the effectiveness of the product. 13) It has been studied intensively with herbicides [14][15][16] and insecticides with the new controlled release formulation and sandwich application technique, the Admire CR product could reduce its phytotoxicity to the rice crop and the degradation losses of the active ingredient.…”

Section: Introductionmentioning

confidence: 99%

Effect of formulations and treatment methods of nursery boxes applied with insecticide on the behavior of imidacloprid in rice paddy fields

2011

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The behavior of imidacloprid was investigated in two paddy plots with conventional release granular formulation and controlled release granular formulation corresponding to before transplanting (BT) treatment and at sowing (AS) treatment (14 days before transplanting) in nursery boxes, respectively. The maximum concentrations of imidacloprid were 30.2 mg/l and 3.0 mg/l in paddy water at 0.5 days after transplanting (DAT), and 278.4 mg/kg and 81.4 mg/kg in 1cm paddy surface soil at 1 DAT for BT and AS treatments, respectively. Dissipation of imidacloprid from paddy water and 1 cm paddy surface soil can be described by biphasic first-order kinetics in the water and single phase first-order kinetics in paddy soil. The half-lives (DT 50 ) of imidacloprid in BT and AS treatments were 2.0 days, 2.4 days during the first phase (7 days) in paddy water, and 12.7 days and 11.0 days in paddy soil, respectively. AS treatment with controlled release granular formulation had lower concentrations of imidacloprid in paddy water and surface soil and has the potential to pose a lower environmental risk than BT treatment with conventional release granular formulation.

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“…Hand placement of tablets on the soil surface would also ensure that the herbicide reached the soil surface and was not trapped by the plant foliage. Dicalcium phosphate has been shown to be an ac ceptable material for use in slow-release technology (5,11,15). Dicalcium phosphate tablets made by the dry press method do not crack, swell, or become deformed when wetted (11,15).…”

Section: Introductionmentioning

confidence: 99%

Slow-Release Delivery System for Herbicides in Container-Grown Stock

Gorski

1993

Weed technol.

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Metolachlor, applied to the surface of leaching columns as dicalcium phosphate tablets, was recovered over a period of 25 d compared with 2 and 3 d for emulsifiable concentrate and granular formulations, respectively. In similar studies, approximately 27% of napropamide was recovered from tablets during the same period. Adding an adjuvant to the napropamide tablet mixture increased the recovery rate to 55%. Tablet hardness and size had little effect on the release rate of napropamide. Tablets containing 4% ai napropamide released greater amounts of herbicide at a single collection period than did tablets containing 1% ai. Adding an adjuvant to the napropamide tablet mixture significantly improved Italian ryegrass control in the area adjacent to herbicide placement.

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Release Rate of Three Herbicides from Controlled-Release Tablets

Cited by 11 publications

References 17 publications

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

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

Effect of formulations and treatment methods of nursery boxes applied with insecticide on the behavior of imidacloprid in rice paddy fields

Slow-Release Delivery System for Herbicides in Container-Grown Stock

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