Herbicide options for weed management and crop tolerance in narrow-leaved blue lupin in Western Canada

Pulse crop production in western Canada is under threat due to the impacts of Aphanomyces root rot. Narrow-leaved blue lupin (Lupin angustifolius L., hereafter lupin) is a potential novel pulse crop of interest in western Canada as it has the benefits of a pulse crop but is resistant to Aphanomyces. Currently, recommendations for weed control via herbicides are limited due to limited registrations, or information on control of western Canadian weeds. The objective of this study was to investigate lupin crop tolerance and western Canadian weed control with 14 pre-seeding herbicides, and 5 in-crop herbicides at 3 locations over 3 years. Crop injury was limited from pre-emergence products; however, precipitation was limited indicating that further investigation is warranted, particularly with products where there were single site-years with injury. Post-emergence applications of topramezone and fomesafen resulted in crop injury causing yield loss. Although weed control with pre-emergence products was limited due to limited precipitation, pyroxasulfone plus sulfentrazone and flumioxazin plus pyroxasulfone showed potential for use. Because precipitation dependency for pre-emergent products, a layered strategy utilizing pre-emergence residual products combined with post-emergence products is likely warranted.