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Published online by Cambridge University Press: 31 May 2012
Five particle types of tetradiphon, three of chloropropylate, and two of Pentac (bis(pentachloro-2,4-cyclopentadien-1,yl) were prepared in similar formulations and tested as sprays against different stages of Tetranychus urticae Koch on bean leaves. The residual, combined topical and residual, and the systemic effects of the formulations were recorded. The target sizes presented by T. urticae stages and by the ranges over which they moved and fed were determined and the numbers of particles per unit area deposited on bean leaves by the formulations used, counted. Positive correlations were shown in all instances between smallness of particle size, number of particles per unit area, and effectiveness, but the relationships between these factors were complex. It is concluded that effectiveness is influenced by a number of factors of which particle size and shape are two which are important but that their effects are often greatly modified by some of the other factors.
Part of a thesis submitted to McGill University by the first-named author in partial fulfilment of the requirements for the degree of Master of Science.