Identification of a paraquat resistant goosegrass population from a central alabama vegetable production field

Authors: MCELROY, JOSEPH - Auburn University; HARRIS, JAMES - Auburn University; Price, Andrew; HARKESS, ALEX - Auburn University; LI, XIAO - Auburn University

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2021
Publication Date: 7/1/2021
Citation: Mcelroy, J.S., Harris, J.R., Price, A.J., Harkess, A., Li, X.S. 2021. Identification of a paraquat resistant goosegrass population from a central alabama vegetable production field. Weed Science. 69(6):648-652. https://doi.org/10.1017/wsc.2021.44.
DOI: https://doi.org/10.1017/wsc.2021.44

Interpretive Summary: Resistance to photosystem I-electron diverting herbicides such as paraquat is rare compared to some herbicide modes of action. A goosegrass population uncontrolled by paraquat in a vegetable production field in St. Clair County, Alabama was collected in Summer 2019. Research was conducted to assess the level of resistance of the suspected resistant population compared to three population with no suspected paraquat resistance. Visual injury at all rating dates and biomass reduction at 28 days after treatment (DAT) of susceptible populations occurred exponentially to increasing paraquat rates. Susceptible biotypes were injured greater than suspected resistant at 3 DAT with biomass recovery at 28 DAT only occurring at rates < 0.28 kg ha-1. Plant death or biomass reduction did not occur for any rate at any date for suspected resistant plants. Paraquat rates that induced 50% or 90% injury or reduced biomass 50% or 90% compared to the non-treated (I50 or I90, respectively) ranged from 10 to 124X higher I50 for suspected resistant compared to S and 54 to 116X higher I90 for R compared to susceptible biotypes. These data confirm a novel paraquat resistant goosegrass biotype in Alabama providing additional germplasm for study of PSI-ED resistance mechanisms.

Technical Abstract: Resistance to photosystem I-electron diverting (PSI-ED) herbicides such as paraquat is rare compared to some herbicide modes of action. A goosegrass population uncontrolled by paraquat (R) in a vegetable production field in St. Clair County, Alabama was collected in Summer 2019. Research was conducted to assess the level of resistance of the suspected resistant population compared to three population with no suspected paraquat resistance (S1, S2, and S3). Visual injury at all rating dates and biomass reduction at 28 days after treatment (DAT) of S populations occurred exponentially to increasing paraquat rates. S biotypes were injured greater than R at 3 DAT with biomass recovery at 28 DAT only occurring at rates < 0.28 kg ha-1. Plant death or biomass reduction did not occur for any rate at any date for R. Paraquat rates that induced 50% or 90% injury or reduced biomass 50% or 90% compared to the non-treated (I50 or I90, respectively) ranged from 10 to 124X higher I50 for R compared to S and 54 to 116X higher I90 for R compared to S biotypes. These data confirm a novel paraquat resistant goosegrass biotype in Alabama providing additional germplasm for study of PSI-ED resistance mechanisms.