Abstract: Field experiments were conducted to determine the influence of nozzle type, spray volume, and adjuvants on herbicide efficacy. Carfentrazone and imazamox, representing contact and translocated herbicides, respectively, were equally or more effective when applied with drift-reducing TurboDrop or Drift Guard nozzles than the conventional flat-fan nozzle in 95% of the comparisons. Imazamox was equally effective when applied in 47, 94, or 190 L/ha spray volume, regardless of nozzle type or adjuvant. Carfentrazone applied in 47 L/ha spray volume controlled flax and sunflower as well as in 94 or 190 L/ha, provided urea ammonium nitrate fertilizer and either nonionic surfactant or methylated vegetable oil were included in the spray mixture. Conversely, carfentrazone with only urea ammonium nitrate was less effective when applied in 47 than in 94 or 190 L/ha spray volume. Carfentrazone and imazamox applied in low spray volumes (47 L/ha) gave consistent control when an effective adjuvant was included in the spray mixture.
Nomenclature: Carfentrazone; imazamox; flax, Linum usitatissimum L.; sunflower, Helianthus annuus L.
Additional index words: Application methods, droplet size, nitrogen fertilizer, spray coverage, spray drift.
Abbreviations: DAT, days after treatment; MVO, methylated vegetable oil, NIS, nonionic surfactant; UAN, urea ammonium nitrate fertilizer; VMD, volume median diameter.