Novel controlled release (CR) agrochemical formulations: Development and evaluations

A comprehensive programme on the development of controlled release (CR) agrochemical formulation is in progress at the National Chemical Laboratory (NCL). The significant accomplishments of this programme are as follows: (1) A crosslinked starch matrix has been developed for application as monolithic granules in the soil. The factors governing the kinetics of agent release from this matrix have been investigated and the study of the structure of the crosslinked matrix has been undertaken by 13CCP/MAS NMR spectroscopy. Procedure for novel single particle release measurement has been developed for understanding the mechanism of release. A granular soil-broadcast formulation of carbofuran has been developed and extensively evaluated in the cultivation of cotton, sorghum, safflower and mustard, giving protection against sucking foliar pests for over two months. (2) Propriety processes based on the less expensive amino resins, specific to the individual agents and release requirements, have been developed by microencapsulating a wide range of agrochemicals. Factors governing the release from these microcapsules have been investigated. Thus (i) A microcapsular seed-coat formulation of carbofuran has been developed and tested for the above crops with much reduced oral toxicity indicating it is over four times safer. Granulation of the above capsules in St-UF matrix has enabled its use in soil broadcast, especially under flooded conditions of paddy cultivation. (ii) An aqueous microcapsular dispersion of quinalphos has been developed, which is used as foliar spray, doubling the period of protection against aphids in okra cultivation. (iii) Microcapsules of chlorpyrifos have been developed, applied both as seed-coat in the powder form and as a soil-broadcast after its granulation, being much superior to all other treatments including phorate in the control of white grub. (3) A CR polymeric coating on commercial pesticide granules, applied as solvent-free self-curing spray in a coating pan has been developed which when applied to Furadan 3G is found to be as effective as St-UF-carbofuran granules on the field. (author). 23 refs, 10 figs, 12 tabs