Potato plants decimated by Colorado potato beetle. Scott’s research has included monitoring CPB populations in different parts of the country for neonicotinoid resistance and cross-resistance with other insecticides. He, along with two other AAFC scientists and the Canadian Horticultural Council, have put together a proposal for a five-year, Canadian Agricultural Partnership-funded project that would further CPB resistance work and assess new management options for controlling the beetles. “Part of what’s been driving this work is the fact that there is concern over what’s going to happen with the neonic products. Whether or not there’s going to be reductions [in use] or complete removal of these products, we don’t know at this point,” Scott says. “I think that’s one of the things that growers would like to see going forward – what are the alternatives, how can we work with the products that are going to be available if the neonics are not?” According to Tracy Shinners-Carnelley, vice-president, research and quality enhancement for Manitoba’s Peak of the Market, there really isn’t very much in the way of effective replacements for neonics – at least not yet. “The regulatory challenges that these chemistries are facing means the industry has no choice but to rethink how we manage CPB,” she says. “The dilemma is, you need to have other effective chemistries to be able to use if you walk away from using neonics. We really don’t have a lot of those options.” Foliar insecticide Shinners-Carnelley says a study led by Peak of the Market has been evaluating management strategies to control resistant CPB populations. The three-year research project wraps up this year, and has assessed different combinations of seed treatments, in-furrow and foliar insecticides. One non-neonicotinoid insecticide that showed good control in the study was the foliar insecticide Delegate. “It performed very, very well,” Shinners-Carnelley says, “but we need to make sure that it is used wisely so we maintain it into the future as an excellent chemistry.” “History has clearly shown that CPB can develop resistance to every chemistry that is thrown at it – it’s just a matter of time. So, we really need to make sure that we’re only using these newer classes of chemistry when they are needed because we need to keep them effective as long as we can,” she says A key part of this stewardship may mean having to revisit and validate economic thresholds for applying foliar insecticides – and potato farmers having to get accustomed to seeing many more beetles in their fields. “Growers have in many cases forgotten what it’s like to have to manage CPB with foliar insecticides, because when the neonics were first introduced and for many years after that, they worked exceptionally well. For the most part, they controlled that pest to the point where growers never really had to worry about tolerating a measurable number of beetles in a field or monitoring defoliation,” Shinners-Carnelley says. “It’s a very uncomfortable feeling for growers to go out and scout and see their plants being chewed on or see patches of the field that have a high infestation of beetles.” A key part of this stewardship may mean having to revisit and validate economic thresholds for applying foliar insecticides – and potato farmers having to get accustomed to seeing many more beetles in their fields. 6 TOP CROP MANAGER/POTATOES IN CANADA | Spring 2018 PHOTO COURTESY OF TRACY SHINNERS-CARNELLEY.