Comparison of sequential preemergence-postemergence and postemergence-alone weed management strategies for red beet (Beta vulgaris L.)

Abstract

Robinson, D. E., McNaughton, K. E. and Bilyea, D. 2013. Comparison of sequential preemergence-postemergence and postemergence-alone weed management strategies during critical period of red beet ( Beta vulgaris L.). Can. J. Plant Sci. 93: 863–870. Weed management during the first 4 wk after red beet emergence is critical to prevent yield loss. The purpose of this research was to compare weed control and red beet tolerance of postemergence (POST) treatments alone (full, split- and micro-rates of pyrazon plus triflusulfuron) with sequential preemergence (PRE) applications of s-metolachlor followed by these POST herbicide treatments. The experiment was carried out for 4 yr as a randomized complete block with four replications. Of the POST alone treatments examined, control of velvetleaf (Abutilon theophrasti Medik.), redroot pigweed (Amaranthus retroflexus L.), common lambsquarters (Chenopodium album L.) and green foxtail [Setaria viridis L. (Beauv.)] was 98, 86, 97 and 62%, respectively. Much more consistent control of all species (i.e., greater than 96%) was measured where the sequential treatment of s-metolachlor was applied PRE followed by POST split- or micro-rates in all study years. Red beet density and soluble solid levels were not different than the weed-free check in any of the POST or sequential treatments. However, red beet yield in the POST single and split-rate treatments alone ranged from 9500 to 12100 kg ha−1, and was significantly less than in the weed-free check (19400 kg ha−1). Yields in the sequential treatments were comparable to the weed-free check. The results of this study confirm that a sequential treatment of PRE s-metolachlor followed by POST split- and micro-rate applications of pyrazon plus triflusulfuron can be safely applied to red beet and control annual weed species.