Insect pest and disease incidence in Northwestern Ontario canola fields

Abstract

While canola has enjoyed a long and lucrative history as a globally successful crop, it has only recently gained popularity in the Thunder Bay District, having been grown locally for just over 10 years. As part of any crop management strategy, it is a vitally important first step to plan mitigation tactics to prevent insect pests and disease infestation. Known insect pests and diseases detrimental to canola in the Manitoba, Saskatchewan and Southern Ontario areas include insect pests such as; Diamondback moth, three species of Flea beetle and the Lygus bug – and diseases such as Aster Yellows, Clubroot and Blackleg. While these insect pests and diseases have begun to migrate to Northwestern Ontario crops, their numbers have not yet proved significantly detrimental to the locally grown canola crops. As part of an Integrated Pest Management plan (IPM), crop rotation is among the recommended measures to prevent pest damage and is recognized as an effective practice for suppressing pests and/or improving biological control, especially with the addition of perennial species. To assist four local farmers with their crop management strategies, this study undertook a net-sweep survey and visual monitoring of eight local privately owned canola fields to determine the effectiveness of crop rotation as a part of their IPM plans. Rotation of canola crops is one such strategy that has been utilized in the prairie provinces and for many generations with a multitude of other crops with success. This study showed that there were significant effects on the incidence of Flea beetles when rotation age was changed but in general the levels of Lygus bugs and Diamondback moths stayed the same. Date of capture had significant effect on the incidence of Diamondback moth and field size had significant differences when divided into above and below 50 acres but no direct effect on insect pest incidence. Diseases existed in such low amounts that it was nearly impossible to attain proper statistical analysis for. Future studies can expand upon this with more rigorous testing measures to ensure proper management of canola in the Thunder Bay District.