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1 January 2018 Control of Protoporphyrinogen Oxidase Inhibiting Herbicide Resistant and Susceptible Palmer Amaranth (Amaranthus palmeri) with Soil-Applied Protoporphyrinogen Oxidase-Inhibiting Herbicides
Alinna M. Umphres, Lawrence E. Steckel, Thomas C. Mueller
Author Affiliations +
Abstract

Palmer amaranth resistance to protoporphyrinogen oxidase (PPO)-inhibiting herbicides has become an increasing problem to producers throughout the southeast region of the United States. Traditionally, these herbicides can be used as foliar-applied and soil-applied in glyphosate resistant (GR) cropping systems to control GR Palmer amaranth. Heavy reliance on PPO herbicides has contributed to the increased selection for PPO inhibitor-resistant (PPO-R) Palmer amaranth biotypes. Dose response greenhouse research was conducted to evaluate the efficacy of soil-applied flumioxazin, fomesafen, saflufenacil and sulfentrazone on a known susceptible (S) and resistant (R) Palmer amaranth biotype. Both R and S populations reached maximum germination at 14 d after treatment (DAT). The data from this study suggests complete control (100%) was achieved for the S biotype at 35 d after treatment (DAT) with all herbicides. The R biotype showed difference among herbicide treatments with flumioxazin and saflufenacil having similar responses in control and fomesafen and sulfentrazone resulting in less control of the R Palmer amaranth biotypes. The calculated relative resistance factor ranged from 3.5 to 6.0, and averaged 5X for the four herbicides. This research indicated that the PPO-R population was still responsive to all tested herbicides, but a low level of resistance was present.

Nomenclature: Flumioxazin; fomesafen; saflufenacil; sulfentrazone; Palmer amaranth, Amaranthus palmeri S. Wats

© Weed Science Society of America, 2017.
Alinna M. Umphres, Lawrence E. Steckel, and Thomas C. Mueller "Control of Protoporphyrinogen Oxidase Inhibiting Herbicide Resistant and Susceptible Palmer Amaranth (Amaranthus palmeri) with Soil-Applied Protoporphyrinogen Oxidase-Inhibiting Herbicides," Weed Technology 32(1), 95-100, (1 January 2018). https://doi.org/10.1017/wet.2017.78
Received: 30 March 2017; Accepted: 1 August 2017; Published: 1 January 2018
KEYWORDS
Herbicide resistance
protoporphyrinogen oxidase herbicides
soils
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