Evaluation of peanut tolerance to mid-season applications of PPO inhibitor herbicides with different surfactants

Authors: PRICE, KATILYN - Auburn University; LI, STEVE - Auburn University; Price, Andrew; BROWNE, FRANCES - Auburn University; BALKCOM, KRIS - Auburn University; CHEN, CHARLES - Auburn University

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/22/2021
Publication Date: 1/27/2021
Citation: Price, K., Li, S., Price, A.J., Browne, F., Balkcom, K., Chen, C.Y. 2021. Evaluation of peanut tolerance to mid-season applications of PPO inhibitor herbicides with different surfactants. Crop Protection. 143:105557. https://doi.org/10.1016/j.cropro.2021.105557.
DOI: https://doi.org/10.1016/j.cropro.2021.105557

Interpretive Summary: Due to the prevalence of ALS-inhibitor resistant weeds throughout the southeast, more PPO-inhibitor herbicides are being utilized to control weeds in peanuts. PPO-inhibitor herbicides can cause crop injury which can be further compounded by different surfactants, application timings, and interactions with environmental stresses. Field studies were conducted in Henry and Escambia counties in AL to investigate the effect of PPO-inhibitor herbicides based treatments on dryland peanut growth and yield when applied at 60, 75, and 90 days after planting, and to study the role of surfactants and chloroacetamide herbicides with PPO herbicide. In addition, the study assess the level of correlation of NDVI data to traditional injury ratings with visual injury ratings and NDVI readings conducted at 14, 21, and 28 days after treatment as well as a yield at the end of the growing season. Yield losses of 16-25% were observed with carfentrazone-ethyl plus HSOC at labeled rates at 75 and 90 DAP compared to the non-treated checks. Overall, treatments with HSOC and/or carfentrazone-ethyl were more likely to cause significant injury, as well as yield loss than treatments with NIS. Peanuts are most sensitive to injury from PPO-inhibitor herbicides at 75 days after planting.

Technical Abstract: Due to the prevalence of ALS-inhibitor resistant weeds throughout the southeast, more PPO-inhibitors are being utilized to control weeds in peanuts. PPO-inhibitors can cause crop injury which can be further compounded by different surfactants, application timings, and interactions with environmental stresses. The objectives evaluated were threefold, 1) investigate the effect of PPO-inhibitor based treatments on dryland peanut growth and yield when applied during sensitive reproduction stages 60 (R4-R5), 75 (R6), and 90 days (R6-R7) after planting, 2) study the role of surfactants and chloroacetamide herbicides with PPO herbicides, and 3) assess the level of correlation of NDVI data to traditional injury ratings. Field studies were conducted in Henry and Escambia counties in AL during 2018 and 2019. Treatments included at 60 DAP, tank mixes of lactofen ((1-ethoxy-1-oxopropan-2-yl) 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoate) with pyroxasulfone 3-[[5-(difluoromethoxy)-1-methyl-3-(trifluoromethyl)pyrazol-4-yl]methylsulfonyl]-5,5-dimethyl-4H-1,2-oxazole) , S-metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-[(2S)-1-methoxypropan-2-yl]acetamide), or dimethenamid-P (2-chloro-N-(2,4-dimethylthiophen-3-yl)-N-[(2S)-1-methoxypropan-2-yl]acetamide), at 75 DAP lactofen, carfentrazone-ethyl(ethyl 2-chloro-3-[2-chloro-5-[4-(difluoromethyl)-3-methyl-5-oxo-1,2,4-triazol-1-yl]-4-fluorophenyl]propanoate), or acifluorfen (5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid), and at 90 DAP carfentrazone-ethyl or lactofen were applied. All herbicide treatments were evaluated with high surfactant oil concentrate and non-ionic surfactant, and included 2,4-DB(4-(2,4-dichlorophenoxy)butanoic acid). Visual injury ratings and NDVI readings were conducted at 14, 21, and 28 days after treatment as well as a yield at the end of the growing season. Yield losses of 16-25% were observed with carfentrazone-ethyl plus HSOC at labeled rates at 75 and 90 DAP compared to the non-treated check in 2018-2019. Overall, treatments with HSOC and/or carfentrazone-ethyl were more likely to cause significant injury, as well as yield loss than treatments with NIS (p< 0.05). Peanuts are most sensitive to injury from PPO-inhibitor herbicides at 75 days after planting.