Systemic application of chlorantraniliprole to cabbage transplants for control of foliar-feeding lepidopteran pests

The diamide insecticide chlorantraniliprole is registered for control of lepidopteran pests in cabbage (Brassica oleracea L.). Taking advantage of its root-uptake systemic properties, chlorantraniliprole is labeled for use with a variety of soil application methods in different countries, depending on pests and local practices. We investigated the efficacy of different cabbage transplant application methods using a leaf consumption bioassay. In the laboratory, we compared different transplant water volumes, characterized the effect of transplant plug size when the insecticide is applied by drenching or soaking the seedling tray, and determined the effect of different soil types. At three field sites, we compared the efficacy of chlorantraniliprole applied in transplant water or as a tray drench or tray soak treatment. In the laboratory, transplant water volume did not affect the level or duration of Trichoplusia ni (Hübner) mortality caused by chlorantraniliprole. When seedling trays were drenched with insecticide solution, transplant plug size did not affect mortality, but when trays were soaked with an equivalent volume of solution, mortality was higher with small plugs. Transplanting plugs treated by transplant water, drench or soak into different soil types did not affect mortality caused by chlorantraniliprole. In the field, transplant water application was the most effective method at all three locations. Tray soak was the most variable application method. Different application methods can be used to take advantage of the systemic characteristics of chlorantraniliprole. Among the methods tested, transplant water and tray drench resulted in more consistent mortality under variable field conditions.