SOIL INSECTICIDES FOR CONTROL OF ROOT WEEVILS IN STRAWBERRIES IN BRITISH COLUMBIA

On a light, gravelly, high-mineral soil in southern Vancouver Island, each of the following treatments gave satisfactory protection from the black vine weevil, Brachyrhinus sulcatus (F.), and the strawberry root weevil, B. ovatus (L.), for the [Formula: see text] life of the strawberry planting: a pre-planting soil application of aldrin at 5 lb., dieldrin at 3 lb., or chlordane at 10 lb. toxicant per acre as a dust, in combination with an application to the transplant roots at 5 lb. of [Formula: see text], [Formula: see text], or 5 per cent dust respectively per 10,000 plants. Three foliage applications, each made at 30 lb. of the appropriate dust per acre during the first 2 years, were not necessary to give protection against the larvae when the soil and roots were treated. The numbers of B. sulcatus larvae per plant and the yields in tons per acre from the treated plots in the third crop year averaged 0 and 2.8, in comparison with 11.6 and 1.1 from the untreated plots. In the latter, many of the plants were killed by B. sulcatus larvae. Applications of [Formula: see text] aldrin dust to the soil, roots, and foliage, to the soil and roots, and to the soil alone gave an average yield per acre in the third year of 1.9 tons in comparison with 1.1 tons when applied to the roots alone or.02 tons from untreated plots. The treatments were not effective against the obscure strawberry root weevil, Sciopithes obscurus Horn, and weevils of the genus Nemocestes [mainly N. incomptus (Horn)].