Herbicide Options for Control of Glyphosate-Resistant Weeds in Sugar Beet

Since the commercialization of glyphosate-­resistant sugar beet in 2008, weed control practices have changed and glyphosate-­resistant weeds have become a major challenge. In the Western Sugar Cooperative production region of Colorado, Montana, Nebraska, and Wyoming, there are currently three known glyphosate-­resistant weeds: volunteer corn, kochia (Bassia scoparia), and Palmer amaranth (Amaranthus palmeri). These weeds can have a tremendous impact on sugar beet yields. If left uncontrolled, one volunteer corn plant every four feet of row can cause up to 25% sugar beet root yield loss. At the same density, kochia could cause up to 45% yield loss, and Palmer amaranth is expected to cause nearly 70% yield loss (Figure 1). To avoid the yield loss shown in Figure 1, it is important to control the weeds early in the growing season.