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By Tracey Baute, Entomologist, Field Crops, OMAFRA
Fewer pest management tools will be available for field crops this year. As of April 2023, all products containing lambda-cyhalothrin including Matador, Warrior, Silencer, Labamba, Voliam Xpress and Endigo are no longer allowed to be used in Canada on crops destined for livestock feed (directly or as by-products). The feed use cancellations by Pest Management Regulatory Agency (PMRA) were based on potential human health risk posed due to the likelihood of residues remaining in milk and livestock products. Despite some field crop uses remaining on the revised labels, all field crops, at some capacity, end up in feed products. With no systems in place to ensure treated crops are segregated from becoming livestock feed, use in all field crops has essentially been eliminated.
Other products are available to manage the key field crop pests (Table 1), though some require the use of older chemistries that pose risks to pollinators. Of particular concern are products for canola and alfalfa pests. Decis (deltamethrin) is the only product registered for cabbage seedpod weevil (CSPW) on canola and is very toxic to bees. The label requires any applications on a blooming crop to be restricted to the evening (after 8 p.m.) when bees are not foraging. Unfortunately, research has shown that the best timing to manage CSPW is during 10 to 20% bloom, if thresholds are reached.
Cabbage seedpod weevil in Canola (M. Moran, OMAFRA).
Alfalfa pest management will also be challenging as some of the products left to manage alfalfa weevil or potato leafhopper (PLH) should not be applied during or close to bloom. Growers will need to do their best to manage these pests by harvesting early and consider planting leafhopper resistant varieties to reduce the risk of PLH in future years.
After a mild winter, both cabbage seedpod weevil (CSPW) and bean leaf beetle (BLB) are likely to survive well and be active early in the season. Both pests are attracted to the most advanced fields in the area. If you have a history of early season BLB, delay soybean planting so that your field is not the first to emerge and use insecticide seed treatments if you have a history of seedling injury. For canola, scout the most advanced winter canola fields that enter bloom first for CSPW. Consider delaying planting spring canola so that these fields are not the first to bloom. Scout for these pests regularly, starting with the most advanced fields first, to determine if these pests are reaching a threshold.
Consider which pests are your primary concern, to determine if additional cultural practices like delayed planting, early harvest or using resistant varieties can reduce the risk where older chemistries are the only options available. For full details on what products are registered for each pest, refer to the OMAFRA Crop Protection Hub (https://cropprotectionhub.omafra.gov. on.ca/).