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Background: Eragrostis plana is an invasive plant in native grassland areas associated with degradation of the Pampa biome. Selective control of E. plana is difficult due to its similarity to other grassland species. There is a lack of information about E. plana control using selective herbicide application equipment. Objective: The present study aimed to evaluate the efficacy of a pressurize rope wick applicator for controlling the invasive plant E. plana as function of different salts of glyphosate, application volumes, and year seasons. Methods: The studies were carried out under field conditions and repeated. The first study evaluated glyphosate salts of isopropylamine, dimethylamine, monoammonium, diammonium, and potassium at doses of 720 and 1440 g ha-1 and clethodim at 60 and 120 g ha-1. The second study assessed application volumes of 8, 24, 40, and 56 L ha-1 using isopropylamine and potassium salts of glyphosate. Results: Glyphosate applied in summer was more effective at controlling E. plana, with less regrowth than glyphosate application in winter. The glyphosate diammonium was more effective at controlling E. plana than isopropylamine, dimethylamine, monoammonium, or potassium salt formulations at 1440 g ha-1. Application volume of glyphosate between 8 and 40 L ha-1 provided similar control of E. plana and pasture selectivity. Conclusions: Glyphosate applied with a rope wick selective applicator was effective in controlling E. plana clumps and was selective to grassland. The control efficacy varied as a function of glyphosate salts and year season, but not due to application volume of 8 and 40 L ha-1.

Some herbicides are commercially formulated with safeners to increase crop selectivity. Fenoxaprop-p-ethyl is formulated with the safener isoxadifen-ethyl for Echinochloa crus-galli control in rice. Safeners act on crops by increasing herbicide metabolism, but this effect may also occur in weeds. The objective of this study was to investigate the effect of the safener isoxadifen-ethyl on the resistance to fenoxaprop-p-ethyl in a biotype of E. crus-galli.A screening of 52 biotypes identified lack of control in the biotype SANTPAT-R treated with the recommended dose of 69 g haThe safener isoxadifen-ethyl present in the commercial herbicide formulation of fenoxaprop-p-ethyl is associated with resistance in the E. crus-galli SANTPAT-R biotype. This resistance is related with herbicide metabolization mediated by GST pathways. This is the first field-selected weed biotype with herbicide resistance due to safener presence in the sprayed formulation. © 2022 Society of Chemical Industry.