Population dynamics and comparative efficacy of insecticide placement for Delia radicum on coastal California broccoli

Field populations of Cabbage Maggot (Delia radicum) were studied in commercial broccoli fields in Guadalupe, California during the 2009 and 2010 production seasons. The distribution and population dynamics of all life stages were studied. In addition, comparative susceptibilities to three commonly used commercial insecticides were established and followed through to crop maturity. Insecticide efficacy depended on application placement with basal sprays being more efficacious than drip-application of these same compounds. The relevance and utility of these results to commercial pest management of this important pest in California cole crops are discussed.