Starch urea formaldehyde matrix encapsulation of solid agrochemicals: III. Studies and bioefficacy trials on double encapsulation

Abstract A technique for the double encapsulation of carbofuran in starch urea formaldehyde (Starch‐UF) matrix has been developed. The solid particles of carbofuran were first microencapsulated with UF resin and these microcapsules were then dispersed in the Starch‐UF matrix to obtain a granular formulation. The rate of release of carbofuran from these granules was found to be governed by its diffusion through the solid UF resin shell and was significantly slower than from the single encapsulated granular formulation prepared by dispersing uncoated carbofuran in Starch‐UF matrix. The bioefficacy of these double encapsulated granules (Encecap‐D 3G), was evaluated for persistence against rice pests in paddy and against subterranean pests in potato, in comparison with conventional formulations of carbofuran, phorate, quinalphos, aldicarb and cadusafos. The persistence of Encecap‐D 3G was found to be better than that of the standard formulation in the cultivation of paddy under flooded conditions and in the cultivation of potato. The order of efficacy was found to be: White grubs—Encecap‐D 3G > quinalphos > cadusafos > aldicarb > phorate > Furadan 3G; Nematodes—cadusafos > Encecap‐D 3G > quinalphos > aldicarb > phorate > ‚Furadan’︁ 3G.