The effect of formulation and method of applying dieldrin on the control of clover root weevil (Amnemus spp.) and on residue levels on pastures

Abstract

Methods of application of different formulations of dieldrin were examined for the control of clover root weevil (Amnemus spp.) and for residue levels on pasture foliage. Two experiments were conducted : the first in which the effectiveness against clover root weevil of surface and sub-surface application of dieldrin granules and the surface application of dieldrin emulsion, was compared ; the second in which the residues of dieldrin on pasture foliage were determined at intervals of one, two, and four weeks after the surface and sub-surface application of dieldrin granules and the surface application of dieldrin dust and emulsion. Granular diazinon was screened as a possible alternative to dieldrin in the first experiment. Clover root weevil control was obtained with dieldrin, regardless of the formulation and method of application, with no significant difference in control between treatments. Diazinon granules were ineffective. The initial residues of dieldrin were highest with the surface application of emulsion, dust, and granules in that order and lowest with sub-surface granule application. Two weeks after the application of surface and sub-surface granules and four weeks after the application of dust and emulsion, residues fell below the level detectable by the method used.