Cabbage (Brassica oleracea L.) Response to Sulfentrazone for Broadleaf Weed Control

Abstract

ABSTRACT Cabbage (Brassica oleracea L.) has few herbicides registered for postemergence weed control. A relatively new herbicide which has selective postemergence potential for use in cabbage is sulfentrazone. Sulfentrazone was applied postemergence to 2–4 leaf stage cabbage at 23, 46, 93, 140, and 187 g active ingredient (a.i.) ha−1. Rates of 23, 46, and 93 g a.i, ha−1 were also applied as a split application. The initial application occurred at the 2–4 leaf stage of growth and the second, at the 6–8 leaf growth stage. Crop injury and leaf discoloration were minimal at 3 days after treatment (DAT). However, injury was substantial at 28 DAT with the 93, 140, and 187 g a.i. ha−1 rale, and with all the split applications in both years of the study. Palmer amaranth (Amaranthus palmeri) and yellowtop (Verbinsina enceluloides) were effectively controlled with all sulfentrazone dosage levels when applied postemergence to cabbage, except at the lowest rate of 23 g a.i. ha−1. Leaf yellowing and crop stunting occurred with the higher rates of sulfentrazone (140 and 187 g a.i. ha−1) as well as with some of the split applications. The cabbage head (core growing point length) was reduced with 187 g a.i. ha−1 sulfentrazone only in 1999. Height of cabbage heads, circumference, and head weight were reduced by 187 g a.i. ha−1 in 1999. When sulfentrazone was applied postemergence to cabbage at dosage levels of 23 to 93 g a.i. ha−1 crop injury, stunting, yellowing, or cabbage size or weight were not adversely impacted. Dosages of 46 and 93 g a.i. ha−1 of sulfentrazone effectively controlled yellowtop and Palmer amaranth which currently are not effectively controlled by any other registered herbicide. At dosages of 46 and 93 g a.i. ha−1 sulfentrazone effectively controlled weeds and had no adverse effect on cabbage size or quality.