Published online by Cambridge University Press: 31 May 2012
Experiments with rutabagas, cabbage, and cauliflower were conducted on mineral soils, mainly with pre plan tin g soil treatments of insecticides applied in bands placed about 2.5 cm below the soil surface (1.25 cm below the seed) in shallow ridges to determine the best insecticides for use in controlling the cabbage maggot. Drench or granular spot applications were also used for transplanted stem crucifers. Broadcast, surface band, and supplementary drench treatments had been tested earlier but were discarded in favor of the band-in-row treatments, mainly because of hazard to beneficial predators and parasites. Of the many materials tested, carbofuran, fensulfothion, and chlorfenvinphos have consistently given the best control throughout the growing season. Trichloronat, E.I. 47031, and mecarbam also gave good results. Thionazin and phorate gave excellent control until 1968 when applied at the exact required depth in the row with machinery; control was often erratic when these materials were applied on a field scale with hand applicators. In 1968, these two insecticides gave less effective early season control and poorer residual control than in previous years. Carbofuran, and phorate, appeared to influence the development of rhizoctonia rot lesions on the sides of the roots more than other materials in all experiments. Rot lesions were more numerous and severe on rutabagas that followed potatoes than on land that had previously been used for cereals. Root maggots in stem crucifers were controlled with a number of insecticides. Methods of application for all cruciferous crops are discussed.