Submitted to: Crop Protection Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/10/2001
Publication Date: N/A
Citation: Interpretive Summary: The herbicide sulfentrazone is very effective on a variety of annual weeds in soybeans, but has caused some injury to soybeans in some circumstances. This injury, while often made worse with cool, wet conditions, has seemed to happen more often with some cultivars, so we designed experiments to determine how much cultivars differ in response to sulfentrazone. Growth chamber studies were conducted using over 40 selected soybean cultivars, including those ancestor lines that are responsible for over 95% of the genetics in modern day cultivars. We used a soil mix, applied the herbicide preemergence after planting, and maintained optimum conditions for growth and soybean injury. We determined responses by visual ratings, heights and dry weights of soybean plants, compared to the untreated control plants of each cultivar 14 days after treatment. The experiment was replicated and was repeated with similar results, so we combined the data of the two runs. We observed notable differences in response to the herbicide among the cultivars tested. Based on the measurements taken, we were able to separate the cultivars into three groups in terms of response: high, medium, or low tolerance to the herbicide. The findings in this study indicate that proper cultivar selection may lower the risk of early season soybean injury and possible yield reduction. These results will be helpful to public and private sector scientists and extension personnel who are planning and recommending weed management and cultivar selection in soybean production and protection.
Technical Abstract: Sulfentrazone has been shown to have excellent soil activity on many small-seeded broadleaf weeds. However, soybean injury in field experiments has been noted under certain environmental conditions where sulfentrazone has been applied. Injury levels in these field experiments have appeared to differ in severity among soybean varieties. Growth chamber studies were initiated in the fall of 1997 with the objective of examining the suspected differences in tolerance among soybean cultivars. Over 40 soybean cultivars, selected from the USDA Soybean Germplasm Collection, were tested for tolerance to sulfentrazone. The soybean cultivars were grown under constant conditions in a growth chamber and treated with sulfentrazone at 0.28 kg ai/ha preemergence. A visually estimated rating of plant injury and height and biomass reduction measurements were made 14 days after treatment. These measurements were compared to the respective untreated check plants of each cultivar. Notable differences among tolerance to sulfentrazone across the cultivars were observed. The cultivars were divided into three groups based on ratings and classified either as having high, medium, or low tolerance to sulfentrazone.