Impact of tank mixing plant hormones with bentazon and mesotrione on sweetpotato injury and weed control

Authors: CAPUTO, GIOVANNI - Clemson University; Wadl, Phillip; MCCARTY, LAMBERT - Clemson University; ADELBERG, JEFFERY - Clemson University; SASKI, CHRISTOPHER - Clemson University; CUTULLE, MATTHEW - Clemson University

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2021
Publication Date: 7/12/2021
Citation: Caputo, G.A., Wadl, P.A., Mccarty, L., Adelberg, J., Saski, C., Cutulle, M. 2021. Impact of tank mixing plant hormones with bentazon and mesotrione on sweetpotato injury and weed control. Agrosystems, Geosciences & Environment. https://doi.org/10.1002/agg2.20185.
DOI: https://doi.org/10.1002/agg2.20185

Interpretive Summary: Sweetpotato is an important specialty crop grown in the US and production has increased by nearly 40% over the past five years. One of the biggest challenges for sweetpotato growers is weed control. Weed management for sweetpotatoes depends on herbicides, between-row cultivation, mowing, and hand removal. However, chemical control is limited to 10 registered herbicides. There are postemergent (POST) herbicides labeled for grass control in sweetpotato, but POST control of broadleaf weeds are only labeled for between-row application, risking damage to sweetpotato leaves during application. Additionally, there are no selective POST herbicides registered to control two of the most problematic weeds of sweetpotato, yellow nutsedge and Palmer amaranth. One possible solution to increase POST herbicide options for sweetpotato is to evaluate safener compounds with the potential to reduce non-target herbicide injury while maintaining efficient weed control. To address this, scientists at Clemson University and the USDA conducted experiments to determine the tolerance of two sweetpotato cultivars to the herbicides bentazon and mesotrione with and without application of safener compounds and determine the response of yellow nutsedge and Palmer amaranth control with bentazon and mesotrione with and without application of safener compounds. This study demonstrated that when safener compounds were included in the tank mix with the labeled herbicide rate that sufficient weed control of yellow nutsedge and Palmer amaranth was obtained. These results suggest that the use of safner compounds could improve sweetpotato tolerance to POST applications of bentazon and mesotrione without reducing herbicide efficiency.

Technical Abstract: Successful weed management is essential to maximize sweetpotato [Ipomoea batatas L. (Lam)] production. Currently, there are no in season applicable selective postemergent (POST) herbicides registered for sweetpotato to suppress broadleaves and nutsedge species. Expansion of bentazon and mesotrione herbicide labels to include sweetpotato would be beneficial for growers. Two experiments were conducted, the first evaluated the dose-response of sweetpotato cultivars Beauregard and Covington to bentazon and mesotrione when melatonin, 24-epibrassinolide, or ascorbic acid (AsA) were included in the tank-mix. The second experiment evaluated the efficiency of bentazon and mesotrione for control of yellow nutsedge (Cyperus esculentus L.) and Palmer amaranth (Amaranthus palmeri S. Wats.), when different doses of melatonin, 24-epibrassinolide, or AsA were added to each herbicide. In the first experiment, when treated with herbicide alone, ‘Beauregard’ exhibited injury levels lower than ‘Covington’ for both herbicides. No injury was observed when plants were treated with plant hormones or AsA alone. At the lowest dose of bentazon and mesotrione, the addition of compounds in the tank-mix significantly reduced percent injury and increased plant tolerance, requiring higher doses of herbicide to cause 10%, 20%, and 30% injury. In the second experiment, the addition of plant hormones and AsA in the tank-mix had no-antagonistic effect on herbicide efficiency, exhibiting similar levels of injuries as herbicides application alone. These results suggest that the use of plant hormones and AsA could improve sweetpotato tolerance to POST applications of bentazon and mesotrione without reducing herbicide efficiency.