Effect of Time and Rate of Application of Bateleur Gold (S-Metolachlor + Flumetsulam) on Phytotoxicity and Weed Control Efficacy in Flue-cured Tobacco

Abstract

Herbicides are usually the first line of defence against weeds and form a formidable pair with mechanical control whether with machinery of hand hoeing. Due to the risk of weed resistance to herbicide control and environmental contamination, there is continuous need for new chemicals to be tested for control of weeds. In this work, the herbicide Bateleur Gold, a factory premix of s-metolachlor and flumetsulam was evaluated to establish the time and rate of application that would give efficacious weed control without causing phytotoxicity. In the first year, the herbicide was included in a screening trial comprising twelve herbicides arranged in a randomised complete block design. After good efficacy when applied immediately after planting, it was selected for further development. In the second year, in a split plot design with four blocks and four treatments, it was applied at 0.455 kg a.i ha -1 applied just after holing out (a.h.o) and at the same rate immediately after planting (i.a.p). A positive control Dual Magnum (smetolachlor) at 2.2 kg a.i.ha -1 i.a.p was used as a check and an untreated control was included. This trial showed that applied a.h.o, Bateleur Gold neither stunted Tobacco nor reduced yield but somewhat reduced weed efficacy especially overall (total weeds) nor grasses while the i.a.p. was ideal and showed no phytotoxicity and had good weed efficacy. In the third year, the i.a.p time of application was tested in a similar design but now more rates of Bateleur Gold were tested. The rates were, Bateleur Gold at 0.455, 0.92, 1.365 and 1.82 kg a.i.ha -1. Dual Magnum at 2.2 kg a.i.ha -1 i.a.p was again included as a check. This work confirmed the potential of the herbicide as a broad spectrum material and showed that the best rate that would ensure broad spectrum control was 0.92 kg a.i.ha-1. Further research could look at application of this material in irrigation water in order to cater for those farmers with centre pivots. In addition, although application a.h.o. does not cause stunting of Tobacco; more work may be needed to show this with greater confidence.

Efficacy of S-metolachlor and flumetsulam (triazolopyrimidine sulfonanilide)+S-metolachlor (chloro-acetanilide) as pre-emergence herbicides in controlling weeds in maize at Chisumbanje Estate

“…This proved that herbicides are effective in reducing the weed spectrum in maize fields. This is in agreement with results by Mazarura (2013) who reported that flumetsulam (triazolopyrimidine sulfonanilide) + S-metolachlor (chloro-acetanilide) was effective in controlling weeds on flue cured tobacco. On the second assessment done 14 days after the application of the pre-emergence herbicide, the flumetsulam (triazolopyrimidine sulfonanilide) + S-metolachlor (chloro-acetanilide) treatment scored a 98% on the EWRC scale in terms of weed density and Smetolachlor treatment scored 90%.…”

“…Flumetsulam (triazolopyrimidine sulfonanilide inhibit acetolactate synthase which catalyses biosynthesis of amino acids. It has been used in controlling weeds in tobacco and has proven to be effective (Mazarura, 2013). Therefore the objectives were to assess the efficacy of S-metolachlor and flumetsulam (triazolopyrimidine sulfonanilide)+Smetolachlor (chloro-acetanilide) pre-emergence herbicides in maize production.…”