Potential wheat yield loss due to weeds in the United States and Canada

Abstract

\n Yield losses due to weeds are a major threat to wheat production and economic well-being of farmers in the United States (US) and Canada. The objective of this Weed Science Society of America (WSSA) Weed Loss Committee report is to provide estimates of wheat yield and economic losses due to weeds. Weed scientists provided both weedy (best management practices but no weed control practices) and weed-free (best management practices providing >90% weed control) average yield from replicated research trials in both winter and spring wheat from 2007 to 2017. Winter wheat yield loss estimates ranged from 2.9 to 34.4%, with a weighted average (by production) of 25.6% for the US, 2.9% for Canada, and 23.4% combined. Based on these yield loss estimates and total production, the potential winter wheat loss due to weeds is 10.5, 0.09, and 10.5 billion kg with a potential loss in value of US$ 2.19, 0.19, and 2.19 billion for the US, Canada, and combined, respectively. Spring wheat yield loss estimates ranged from 7.9 to 47.0%, with a weighted average (by production) of 33.2% for the US, 8.0% for Canada, and 19.5% combined. Based on this yield loss estimate and total production, the potential spring wheat loss is 4.8, 1.6, and 6.6 billion kg with a potential loss in value of US$ 1.14, 0.37, and 1.39 billion for the US, Canada, and combined, respectively. Yield loss in this analysis is greater than some previous estimates, likely indicating an increasing threat from weeds. Climate impacts yield loss in winter wheat in the Pacific Northwest, with percent yield loss highest in wheat-fallow systems with less than 30 cm of annual precipitation. Continued investment in weed science research for wheat is critical for continued yield protection.