The interaction of pyridate and 2,4-DB in peanut (Arachis hypogaea), Florida beggarweed (Desmodium tortuosum), and sicklepod (Senna obtusifolia)

Tank-mixed combinations of pyridate and 2,4-DB were synergistic with respect to sicklepod control and independent with respect to Florida beggarweed control and peanut tolerance in greenhouse studies. Leaf absorption of C-14-pyridate was generally enhanced by the addition of 2,4-DB. Translocation of C-14-pyridate out of the treated leaf did exceed 21% of the amount absorbed across all species, and C-14-pyridate was not affected by the addition of 2,4-DB. Sensitivity of peanut, Florida beggarweed, and sicklepod to pyridate was independent of both adsorption and translocation. Metabolic detoxification of pyridate into a benign metabolite was highest in the tolerant peanut, lowest in highly susceptible Florida beggarweed, and intermediate in slightly susceptible sicklepod. Absorption of C-14-2,4-DB by peanut was increased by approximately 10% with the addition of pyridate. No such increase was observed in either Florida beggarweed or sicklepod. Translocation of C-14-2,4-DB out of the treated leaf was not affected by the addition of pyridate in any of the three species evaluated.