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Use of exclusion netting for insect pests of brassica vegetables

Project Code STB19-010

Project Lead

Christine Gagnon and Kathryn Makela Agriculture and Agri-Food Canada

Objective

Conduct trials in Ontario and Quebec to test and demonstrate the effectiveness of durable exclusion netting for cabbage maggot, swede midge, flea beetles and lepidopteran management in large scale production of brassica vegetables

Brassica vegetables are produced widely in Canada (Ontario, Quebec, British Columbia, and Atlantic Provinces), contributing a farm gate value of 225 million dollars in 2017. These crops are plagued by cabbage maggot, (Delia radicum) and swede midge, (Contarinia nasturtii). Cabbage maggot feeding on roots can kill or stunt young plants, and significantly reduce the marketability of crops. Swede midge can cause important reductions in crop yield due to larval feeding on the plant above ground. Current management practices for these pests include the extensive use of insecticides, including chlorpyrifos, diazinon and imidacloprid. Pest resistance to chlorpyrifos, one of the most commonly used, is increasing and a recent Canadian survey revealed resistance in up to 87 percent of cabbage maggot insects tested in Newfoundland.

Previous work with insect netting for exclusion of cabbage maggot in brassica crops conducted by Agriculture and Agri-Food Canada in British Columbia and the Atlantic Provinces indicated that polyethylene, woven netting was highly efficacious at protecting crops from damage, confirming benefits experienced on thousands of acres by European farmers. Selection of an appropriate netting gauge provides an opportunity to also exclude other problematic insects such as swede midge, lepidopterans and flea beetles. However, uptake of the technology in the major production provinces has been slow. This project will further develop the technology to target additional pests and will implement knowledge and technology transfer activities aimed to accelerate uptake of this technology.

In addition to insect control, abiotic conditions (for example air humidity, soil and air temperature) under the netting and the impact on crop quality and maturity, as well as disease and insect development will be measured. Current equipment for deploying and removing the netting on large fields will be tested and demonstrated. Knowledge and tech transfer activities to increase grower awareness throughout the project will include social media outreach and videos as well as field day demonstration. Collaborating growers will be surveyed on their experience with the technology and a cost-benefit analysis of the implementation of the technology at commercial scale in different production settings will be prepared and shared. The adoption of this alternative management practice for insect pests of brassica vegetables could reduce or completely eliminate the need for chemical treatments, addressing concerns about environmental pesticide contamination and insecticide resistance. The impact for growers is expected to be high, as several insecticides used to manage brassica pests are currently under re-evaluation by the Pest Management Regulatory Agency, and if lost as a result, could leave growers in a vulnerable position to protect their crops.

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