Control of Volunteer Horseradish and Palmer Amaranth (Amaranthus palmeri) with Dicamba and Glyphosate

Abstract

Management of volunteer horseradish is a challenge when it is grown in rotation with other crops, such as corn and soybean. Although volunteer horseradish may not cause yield loss, these plants serve as hosts for various soilborne pathogens that damage subsequent horseradish crops. In addition to volunteer horseradish, glyphosate-resistant Palmer amaranth is becoming difficult to control in southwestern Illinois, as a consequence of the plant’s ability to withstand glyphosate and drought, produce many seeds, and grow rapidly. Field studies were conducted to evaluate the effect of glyphosate and dicamba on volunteer horseradish and Palmer amaranth control in 2014 and 2015. Glyphosate alone (1,265 and 1,893 g ae ha−1) and glyphosate plus dicamba at the high rate (1,680 g ae ha−1) provided the greatest volunteer horseradish control, ranging from 81% to 89% and 90% to 93%, respectively. Measures of root biomass reduction followed similar trends. Glyphosate alone provided the greatest reduction in volunteer horseradish root viability (79% to 100%) but was similar in efficacy to applications of glyphosate plus dicamba in most comparisons. Efficacy of PRE-only applications on Palmer amaranth control ranged from 92% to 99% control in 2014 and 68% to 99% in 2015. However, PRE-only applications were often similar in efficacy to PRE followed by (fb) glyphosate plus dicamba applied POST. Treatments containing flumioxazin did not control Palmer amaranth as well as other treatments. POST applications alone were not effective in managing Palmer amaranth. Many of the PRE fb POST treatment options tested will improve resistance management over PRE-only treatments, provide control of Palmer amaranth, and allow horseradish to be planted the following spring.

Residual herbicides affect critical time of Palmer amaranth removal in soybean

“…Similarly, Umphres et al (2018) reported 98 and 100% biomass reduction of PPO-inhibitor-resistant and susceptible Palmer amaranth biotype, respectively. Despite the difference between years, Palmer amaranth density and biomass were reduced by PRE herbicides, which supports previous studies that obtained a high level of Palmer amaranth control using flumioxazin + pyroxasulfone (Bernards et al, 2010;Hay, 2017;Jenkins et al, 2017;Mahoney et al, 2014;Young et al, 2010).…”

Effect of PPO-Inhibiting Herbicides on the Growth and Sex Ratio of a Dioecious Weed Species Amaranthus palmeri (Palmer Amaranth)

“…The post-emergence application of the PPO-inhibiting herbicide, fomesafen, did not lead to a departure of the expected 1:1 sex ratio, and was included in the greenhouse study as a comparison. The field trial confirmed that A. palmeri was sensitive to both of these PPO-inhibiting herbicides in 2015, and resistance to PPO-inhibiting herbicides was not suspected in any of the populations used in this study; however, in 2016, the Collinsville population was documented as 18.8% heterozygous for the glycine 210 deletion which confers PPO-inhibitor-resistance to fomesafen and lactofen, indicating the early stages of resistance development [42,43].…”

Evaluating risks of plant growth regulator–resistant soybean technologies to horseradish production

“…Both Johanning et al (2016) and Rundle et al (2007) indicated that 2,4-D is highly effective for volunteer horseradish control. Although 2,4-D can be a tool to manage this pest, the management of volunteer horseradish is still a challenge when horseradish is grown in a relatively short rotation cycle with other crops such as corn and soybean (Jenkins et al 2017). Our results should help growers better understand the importance of specialty crop field placement in areas where 2,4-D-and/or dicamba-resistant crops are prevalent, as well as how to better use these crops in relation to possible drift events.…”