Carrot Rust Fly (Diptera: Psilidae) Control: Monitoring Adults to Schedule Post-Plant-Emergence, Soil-Applied Larvicides

Sticky-trap catches of adult Psila rosae (F.) were used to time the application of rowband sprays of fensulfothion, carbofuran, chlorpyrifos, and diazinon to seedling carrots. The results demonstrated that adult monitoring can be used successfully to schedule larvicide sprays on carrots grown for fresh market in western Washington. Both one and two applications of carbofuran and fensulfothion at 31.0 and 37.5 mg of AI per 300 m of row, respectively, reduced carrot rust fly feeding damage to less than 10% of that in the untreated controls when carrots were exposed to either first or second generations of larvae. Soil surface sprays applied at time of planting were also effective. Chlorpyrifos and diazinon provided moderate to inadequate protection. Unacceptably high residues of fensulfothion and fensulfothion sulfone (0.58 to 0.67 ppm) were recovered from treated carrots at harvest time, even though only two soil surface sprays were applied and the last application was made 60 days before harvest. Carrots receiving only one application of fensulfothion and carrots treated with carbofuran were not analyzed for insecticide residues.