Effects of Picloram and Tebuthiuron on Establishment of Ryegrass Winter Pasture

Abstract

Ryegrass [Lolium perenne L. (including L. multiflorum Lam.)] was established in plots 75 days (and 16 cm rainfall) after treatment with spray and granule formulations of picloram at a rate of 3.4 kg/ha. Tebuthiuron spray and granule formulations applied at the rate of 1.1 kg/ha 261 days (and 68 cm rainfall) before planting provided effective weed control and allowed successful grass establishment. Tebuthiuron spray and granules at 3.4 kg/ha, however, prevented both weed growth and ryegrass establishment when applied 261 days before planting. Sufficient residues from this rate of tebuthiuron were present after 499 days (and 116 cm rainfall) to prevent revegetation by johnsongrass on 95% of the treated area. The soil type in the plot area was a black clay loam classified as udic pellustert.