Perspectives on Potential Soybean Yield Losses from Weeds in North America

Abstract

Weeds are one of the most significant, and controllable, threats to crop production in North America. Monetary losses because of reduced soybean yield and decreased quality because of weed interference, as well as costs of controlling weeds, have a significant economic impact on net returns to producers. Previous Weed Science Society of America (WSSA) Weed Loss Committee reports, as chaired by Chandler (1984) and Bridges (1992), provided snapshots of the comparative crop yield losses because of weeds across geographic regions and crops within these regions after the implementation of weed control tactics. This manuscript is a second report from the current WSSA Weed Loss Committee on crop yield losses because of weeds, specifically in soybean. Yield loss estimates were determined from comparative observations of soybean yields between the weedy control and plots with greater than 95% weed control in studies conducted from 2007 to 2013. Researchers from each US state and Canadian province provided at least three and up to ten individual comparisons for each year, which were then averaged within a year, and then averaged over the seven years. These percent yield loss values were used to determine total soybean yield loss in t ha−1and bu acre−1based on average soybean yields for each state or province as well as current commodity prices for a given year as summarized by USDA-NASS (2014) and Statistics Canada (2015). Averaged across 2007 to 2013, weed interference in soybean caused a 52.1% yield loss. Based on 2012 census data in the US and Canada soybean was grown on 30,798,512 and 1,679,203 hectares with production of 80 million and 5 million tonnes, respectively. Using an average soybean price across 2007 to 2013 of US $389.81 t−1($10.61 bu−1), farm gate value would be reduced by US $16.2 billion in the US and $1.0 billion in Canada annually if no weed management tactics were employed.

Germination of Chloris barbata, Cynodon dactylon, and Cyperus rotundus from Angola at Constant and Alternate Temperatures

“…Weeds are a major constraint for crop production and, among crop pests, are responsible for the highest potential yield losses [1]. In the absence of adequate control measures, weeds are estimated to cause an average of 50% yield loss for maize and soybean in North America [2,3]. Similar results were reported in various studies from European countries [4,5], and even higher losses were observed for maize, sorghum, and rice in Africa [6][7][8].…”

Critical time for weed removal in glyphosate-resistant soybean as influenced by preemergence herbicides

“…Major factors that influenced CTWR and that varied with locations were weed density and time of weed emergence. The CTWR in crop fields with high weed density and early weed emergence is expected to occur earlier than in those locations with low weed density and late weed emergence (Jeschke et al 2011;Kropff et al 1987;Soltani et al 2017). For example, in our study, without the influence of PRE herbicides, locations with high weed densities and early emergence of weeds had an earlier CTWR (V1 to V2 of soybean stage) compared with a location (HAL in 2016) with very low weed density and late weed emergence, resulting in an unusually late commencement of CTWR at V6.…”

Influence of Adjuvants on the Efficacy of Tolpyralate plus Atrazine for the Control of Annual Grass and Broadleaf Weeds in Corn with and without Roundup WeatherMAX<sup>®</sup>

“…Weed interference during the early stages of corn development can cause physiological changes in the plant and lead to yield loss [1]. A study conducted across the corn producing regions of the United States and Canada found that in the absence of any weed management tactics, corn yield loss due to weed interference was 50% [2]. The critical weed free period (CWFP) in corn delineates the time period during which weed interference must be minimized to prevent corn yield loss.…”