Leaf Disk Bioassay for Cabbage Looper Susceptibility, 1990

Fresh cabbage purchased from a local grocery store was cut into disks measuring 90 mm in diam. Disks were dipped in chemical mixtures (see tables) and allowed to air dry on a sheet of organdy cloth to allow drainage. The disks were then placed in 90 mm Pyrex petri dishes; two disks per plate in Test I and one disk per plate in Test II. Five healthy, newly-molted secondinstar CL larvae were tested in each plate. Each plate was checked for larval mortality at approximately six h, 18 h and at 24 h intervals thereafter for seven d. Mortality was determined by prodding the larvae with a blunt probe and dead larvae were removed.