Comparison of standard and organic pesticides as well as herbal products for control of insect pests of cabbage (Brassica oleracea) in Saskatchewan

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Sarah Wist


Many insect pests can potentially damage cabbage (Brassica oleracea) grown in Saskatchewan. Root maggots (Delia spp), flea beetles (Phyllotreta spp) and cabbage worms (Order: Lepidoptera) are the main concerns. The objective of this project was to assess the potential to use of companion planted herbs or herbal essential oils as control methods for these pests. Standard synthetic pesticides were used as a check treatment. Organic pesticides and a row cover were also tested and compared to an untreated control. The herbal treatments were garlic or thyme plants interplanted with the cabbage crop along with foliar sprays of garlic or thyme oil. The pest control treatments were compared in trials using both transplanted and direct seeded cabbage. The standard and organic pesticide regimes both effectively controlled all three of the insect pests, and resulted in similar head yields in both the transplanted and direct seeded cabbage crops. The row cover successfully prevented insect damage but created problems with weed control and required extra materials and labour to construct. The microclimate created by the row cover decreased growth of the direct seeded crop. None of the herbal products provided effective control of any of the insect pests of cabbage. In conclusion, cabbage can be successfully grown in Saskatchewan with minimal losses to insects using either standard synthetic or organic pesticides, but the herbal were not effective in the form and rates tested in this project.