2022 Fleabeetle Canola Herbivory

The Canola Council of Canada advises that canola should be sown with high seeding densities and preferably using larger seed size (up to 2.2mm). Moreover, seeding later in the season should be considered rather than seeding on earlier dates. Briefly, greater plant densities produced by high seeding rates compensate for flea beetle leaf damage. More tolerant seedlings to flea beetles have been observed to be affected by seed size and canola sown mid-May to early-June. Late sown less affected by flea beetle damage than canola seeded in late-April to early-May. Currently, there is limited research showing how all these recommendations, acting in conjunction, affect canola production. Therefore, this study aims to evaluate the impact of seeding rate, seed size, and seeding date on flea beetle damage and populations. Furthermore, a split-plot factor analysis will also allow us to examine interaction effects between seeding rate, seed size and seeding date. Further insight on interactions effects will allow us to measure the true flea beetle response to these recommendations, and provide new recommendations based on these possible interactions.

The objective is to evaluate the impact on flea beetle leaf damage and flea beetle population of seeding date (late-April to early-May and second to third week of May), seed size (small, large and unsorted), and seeding rate (112,56 and 168 plant m-2). The seeding date for all these trials had to be pushed further due to weather constraints. Therefore, “early seeding dates correspond to canola sown from the second to the third week of May and “Late” dates correspond to canola sown from the fourth week of May to the first week of June.