Sensitivity of early vegetative stage corn to reduced rates of trifludimoxazin + saflufenacil

Abstract

Trifludimoxazin + saflufenacil is a premix protoporphyrinogen oxidase-inhibiting herbicide with both preemergence and postemergence activity pending registration in the United States for burndown application ahead of planting corn, soybean, grain sorghum, and wheat. With early-season corn growth often occurring simultaneously with preplant burndown of fields in later-planted soybean and grain sorghum, the odds of negative impacts associated with off-target herbicide movement to the crop increase. Field studies were conducted in 2024 at seven different sites to evaluate the effect of reduced rates of trifludimoxazin + saflufenacil (12.5% to 0.4% of the lowest proposed labeled application rate of 38.3 g ai ha ^-1 ) applied to 2- or 4-leaf (lf) corn. Corn injury 7 days after treatment (DAT) for the early and later application timings ranged from 21 to 3% and 19 to 5%, respectively, while at 14 DAT these respective ranges were 12 to % and 8 to 1%. At 28 DAT, the highest rate (1/8x) applied to 2-lf corn resulted in 6% visible injury while no other treatment surpassed 3% injury. Early season plant height was negatively impacted, more so at the three highest rates applied and at the earlier timing, but this reduction did not impact yield, therefore application of trifludimoxazin + saflufenacil adjacent to corn in the early vegetative stages of growth should be avoided. However, corn affected by off-target movement should be expected to fully recover following 2-lf exposure, with no impact on yield and minimal yield impact at later timing (<3% reduction), given adequate growing conditions and agronomic/pest management practices.