Technical notes. The insecticidal values of two isomers of DDD

Abstract

Following trials with DDD (TDE) for the control of the lucerne leaf roller (Tortrix divulsana (Walk.) ) in the Lockyer Valley (to be published), the question of the relative toxicities of the p.p' and o.p' isomers arose. Technical grade DDD available in Queensland at the time was formulated as 30 per cent. total isomers, 20 per cent. being p.p' and the remaining 10 per cent. mostly the o.p' isomer. Overseas literature (Riemschneider 1950) indicates that the order of decreasing efficaciousness of DDD isomers is p.p', m.p', o.p', o.m', and o.o'. During 1957, two trials each a 5 x 4 layout with plot size of 1/100 ac were established. Four samples of DDD with 30 per cent total isomers were formulated with the same solvent and emulsifier. All differed, however, in the ratio of p.p' to o.p'.