Identification of a paraquat-resistant goosegrass (Eleusine indica) population from a central Alabama vegetable production field

A goosegrass [Eleusine indica (L.) Gaertn.] population uncontrolled by paraquat (R) in a vegetable production field in St. Clair County, AL, was collected in summer 2019. Research was conducted to assess the level of resistance of the suspected resistant population compared with three populations with no suspected paraquat resistance (S1, S2, and S3). Visual injury at all rating dates and biomass reduction at 28 d after treatment (DAT) of S populations occurred exponentially to increasing paraquat rates. S biotypes were injured more 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 with the non-treated (I-50 or I-90, respectively) ranged from 10 to 124 times higher I-50 for R compared with S and 54 to 116 times higher I-90 for R compared with S biotypes. These data confirm a paraquat-resistant E. indica biotype in Alabama, providing additional germplasm for study of resistance to photosystem I electron-diverting (PSI-ED) resistance mechanisms.

Automated summary

The study identified a suspected paraquat-resistant goosegrass population in Alabama, which showed exponentially increasing visual injury and biomass reduction at different paraquat concentrations compared to populations without resistance.