Release Characteristics of Starch Xanthide Herbicide Formulations

Abstract

A laboratory procedure was developed using a cucumber (Cucumis sativus ‘Straight Eight’) root‐length bioassay to measure the relative rate of release of herbicides entrapped in various starch xanthide (SX) matrices. SX herbicide formulations placed in vials containing deionized water were decanted periodically and evaluated by bioassay to examine herbicide released into the water. In leaching experiments, fractions of effluent were collected from glass columns containing SX herbicide formulations applied to a glass‐wool pad resting on a sand bed. Collected aqueous fractions were bioassayed. The herbicides examined were salt and ester formulations of picloram (4‐amino‐3,5,6‐trichloropicolinic acid), ester formulations of 2,4‐D [(2,4‐dichlorophenoxy)acetic acid], and salt formulations of dicamba (3,6‐dichloro‐o‐anisic acid). Comparison of salt and ester starch xanthide formulations of picloram indicated that the ester formulation had a release rate three to five times slower than that of the salt formulation. Differences were noted between starch xanthide formulations of salt herbicides designated as fast and slow releases.

A study towards release dynamics of thiram fungicide from starch–alginate beads to control environmental and health hazards

“…An ideal pesticide formulation would be one which limits the amount available at any time to be adequate for pest control and leave minimum residues on crops and in environment [1][2][3][4][5][6][7]. This can be achieved by encapsulating the chemicals in the polymeric matrix.…”

Polysaccharides as safer release systems for agrochemicals

“…Starch-based hydrogels are most commonly used hydrogels meant for agrochemical delivery system (Baur 1980;Schreiber et al 1988;Jana et al 2001;Frederiksen et al 2002). In the field, soil moisture, soil microorganisms, and soil enzymes (such as amylases) control the release of the active compounds from polymer matrices (Shasha et al 1981;Wing and Otey 1983;Trimnell et al 1985).…”

In vitro release dynamics of thiram fungicide from starch and poly(methacrylic acid)-based hydrogels

“…These devices consist of a pesticide in a polymer in the form of a microcapsule or granule [16]. The polymer-encapsulated compounds are superior to non-encapsulated commercial formulations in extending activity [17], reducing evaporative and degradation losses [18], reducing leaching [19], and decreasing dermal toxicity [20]. Water [21], soil moisture [22], soil microorganisms and soil enzymes such as amylases [23] release the active compounds from polymer matrices in controlled and sustained manner.…”