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Canola Growers - "Get Ready for Weevils"

With the summer like days we've been having, the canola crop is quickly advancing. Winter canola fields in the Thamesville area have already bolted and will be flowering by the end of the week. As soon as the flowers start opening up, cabbage seedpod weevil will be there and will need to be managed.

Figure 1. Adult Cabbage Seedpod Weevil (T. Baute, OMAFRA)

Our on-farm research trials conducted last year, a project involving University of Guelph, OMAFRA and Agriculture and Agri-Food Canada researchers produced some great results and demonstrated the importance of managing CSW during early flowering. When you spray comes down to economics. If budget only allows for 1 application of insecticide, our research results indicate the best timing for one application is at mid flowering, that is, 7-10 days after the first flowers are noticed in the field (Table 1). If budget allows, yield was better when two applications of insecticide could be made, one at first flower and a second application 7-10 days later, during mid flowering.

Table 1. Yield (Kg/ha @ 8.5% moisture) from winter canola field plots at three locations in Ontario sprayed with MatadorTM at various timings during bloom, 2006.

Values followed by the same letter are not significantly different, P<0.05, Tukey's mean separation test.

Spring canola fields tend to have less cabbage seedpod weevil moving into them and tend not to require insecticide applications. Matador is the only product currently registered for CSW in Canada. See the product label for further details and restrictions. Matador is most effective when sprayed in the early morning or evening to avoid the heat of the day which can break down the chemical. Contact local beekeepers before you spray and spray in the evening when bees are least active in the field.