Tolerance of Soybean Genotypes to Metribuzin1

Abstract

AbstractMetribuzin [4‐amino‐6‐tert‐butyl‐3‐(methylthio)‐as‐triazin‐5(4H)‐one] controls several troublesome weeds in soybean [Glycine max (L.) Merr.], but may result in excessive soybean injury. Previous research has shown differential soybean cultivar responses to metribuzin. Sixteen determinate soybean genotypes, including the new cultivar ‘Dowling,’ and several genotypes whose tolerance have not been reported previously, were evaluated in a greenhouse for their response to 0.3, 0.6, and 1.1 kg/ha metribuzin applied preplant incorporated. Ts 72‐6, ‘Forrest,’ ‘Davis,’ ‘Hutton,’ Dowling, ‘McNair 800,’ and Ts 74‐23, were moderately tolerant; ‘Dare,’ PI 200492, ‘Pickett 71,’ ‘Bossier,’ and ‘Ransom,’ were moderately sensitive; and ‘Semmes,’ ‘Hampton 266A,’ ‘Tracy,’ and Ts 74‐34, were sensitive to the use rate of 0.6 kg/ha when evaluated 2 weeks after planting. Increased rates of metribuzin resulted in increased injury within a given genotype. Metribuzin should not be used for weed control when sensitive cultivars are being grown.