oa Journal of the Entomological Society of Southern Africa - Isazophos, a promising new insecticide for control of larvae of fossorial rhizophagous beetles (Coleoptera: Scarabaeoidea) in pineapple fields
The value of isazophos (O-(5-chloro- I -methylethyl- IH- I,2, 4, -triazol-3-y!l) O, O-diethyl phosphorothioate) as a preplant soil insecticide and nematicide in pineapple production was assessed at dosages of 2,5 to 15,0 kg/ha, It was concluded that 10 kg/ha is the optimum dosage of both biological efficacy and economics arc considered. Even at 5kg/ha, the residual efficacy against larvae of the beetle Adoretus tessulatus Burm, exceeded that of the current standards, HHDN and dieldrin, for more than 48 weeks according to laboratory bioassays. In field trials in which fruit yield, root mass, nematode root-galling and ratoon sucker development were measured, outstanding results were obtained with isazophos at 10 kg/ha: e.g. plant- and ratoon-crop yields were respectively double and more than quadruple that or the untreated control There were no detectable residues in fruit at time of harvest even after a dosage of 15 kg/ha. Evidence was obtained that isazophos has a high potential as a postplant topical soil treatment for elimination of rhizophagous beetle larvae.
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