EFFECT ON 2-SPOTTED SPIDER MITE TETRANYCHUS URTICAE OF DICOFOL CONCENTRATION AND DEPOSIT DISTRIBUTION ON LEAF SURFACE

Dicofol was applied to bean leaf discs in various ways. The number of drops per disc, the concentration of dicofol in each drop, and the size of the drops were related to egg laying and mortality of adult female mites placed on the discs. Under the conditions of the experiment, an increase in concentration above normal field strength (0.046% active ingredient) had little effect, even though the deposits were discontinuous and similar to those expected from low-volume spraying. Repellency of dicofol to mites was reaffirmed and toxicity effects were significant when about one-quarter of the leaf surface was covered by deposit. © 1968, Entomological Society of Canada. All rights reserved.