Influence of water quality, formulation, adjuvant, rainfastness, and nozzle type on efficacy of fomesafen on Palmer Amaranth (Amaranthus palmeri) control

Authors: Nandula, Vijay; Molin, William; BOND, J - Delta Research & Extension Center

Submitted to: American Journal of Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2018
Publication Date: 7/19/2018
Citation: Nandula, V.K., Molin, W.T., Bond, J.A. 2018. Influence of water quality, formulation, adjuvant, rainfastness, and nozzle type on efficacy of fomesafen on Palmer Amaranth (Amaranthus palmeri) control. American Journal of Plant Sciences. 9:1660-1676.

Interpretive Summary: Protoporphyrinogen oxidase (PPO) inhibitors are one of the few remaining postemergence herbicide options for controlling Palmer amaranth in soybean growing areas of Mississippi. Scientists from the Crop Production Systems Research Unit, USDA-ARS, Stoneville, MS and Mississippi State University conducted greenhouse studies to evaluate factors effecting the efficacy of fomesafen, a PPO inhibitor, on Palmer amaranth including: quality of spray carrier (water), formulations, adjuvant, rainfastness, and nozzle type. Water quality, formulation, adjuvant, rainfastness, or nozzle type did not affect the activity of fomesafen under optimal application conditions in the greenhouse. The research reported here is very relevant in that application parameters evaluated here can be modified to prolong the sustainability of PPO inhibitors as well as slow the spread of resistance to PPO inhibitors such as fomesafen, which is clearly the preferred treatment in glyphosate-resistant soybean.

Technical Abstract: Protoporphyrinogen oxidase (PPO) inhibitors are one of the few remaining postemergence herbicide options for controlling Palmer amaranth in soybean growing areas of Mississippi. Most Palmer amaranth populations in Mississippi are resistant to both glyphosate and acetolactate synthase inhibitors. Resistance to PPO inhibiting herbicides in Palmer amaranth has very recently been reported in Arkansas, Tennessee, and isolated pockets of Mississippi. A significant proportion of reports of PPO inhibitor failures in Mississippi are not considered to be resistance-related at this time. Therefore, the objective of this research was to evaluate factors effecting the efficacy of fomesafen on Palmer amaranth including: quality of spray carrier (water), formulations, adjuvant, rainfastness, and nozzle type. Water quality, formulation, adjuvant, rainfastness, or nozzle type did not affect the activity of fomesafen under optimal application conditions in the greenhouse.