Experiments to Control Acorn Weevils With Systemic Insecticides

Bidrin ® 3-(dimethoxyphinyloxy)-N, N-dimethyl- cis -crotonamide, phorate, disulfoton, and phosphamidon (applied as trunk implantations and in granular formulations on the humus beneath the tree crown) were used to control the acorn weevils ( Curculio spp. Curculionidae, Coleoptera) on Quercus rubra L. and Quercus alba L. Mixtures of dimethyl sulfoxide and technical formulations of Bidrin, phorate, and Isolan ® , 1-isopropyl-3-methyl-5-pyrazolyl dimethylcarbamate were also used. Applications were made only once durng the first part of June 1961, 1962 and 1963. Factors which reduce acorn viability were influenced and the production of non-weeviled acorns was increased by the use of direct trunk implantation methods which were more effective than granular applications. The results, however, were not consistent from year to year. The most effective insecticides tried were phorate and Bidrin applied at the rate of 6 to 8 ounces of technical material per tree.