Weed Control Efficacy of Herbicides in Wheat under Strip Tillage System

Abstract

Wheat production can successfully be increased by growing under strip tillage system, but weed is considered as a major obstacle in this reduced tillage system. Labour scarcity and high wage of labour makes manual weed control more difficult in this minimum tillage system and therefore use of herbicides is increasing day by day. Though most of the available herbicides are recommended for rice, some pre- and post-emergence herbicides were tested in the present study, for wheat, conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during November 2012- March 2013, to evaluate the performance of those herbicides on controlling weeds in wheat under strip tillage system. Eighteen treatments comprising different combinations of four pre-emergence (pendimethalin, pretilachlor, butachlor and pyrazosulfuron-ethyl) and two post-emergence (ethoxysulfuron and 2,4-D amine) herbicides belonging to four modes of action were used in the study including no weeding and weed free as a control in a randomized complete block design (RCBD) with three replications. The study revealed that herbicides significantly reduced weed density and dry matter under strip tillage system giving up to 233% yield increase over control. Pendimethalin followed by ethoxysulfuron, Pendimethalin followed by 2,4-D amine and pretilachlor followed by ethoxysulfuron reduced weed biomass by 82% compared to non treated weedy plots and produced 213-233% increased yield over weedy control and even produced 2-8% higher grain yield over weed free control. Pendimethalin followed by one hand weeding and pretilachlor followed by one hand weeding also controlled weed biomass by 78-80% with 138-151% yield increase over control whereas sole application of pendimethalin and pretilachlor controlled weed biomass only by 38-47% and gave 97-123% increased yield over control. Sole application of pyrazosulfuron-ethyl performed as the worst efficient herbicide treatment in strip tilled wheat. The performance of butachlor was also found less efficient in this system when applied alone. Nevertheless, the efficiency of both pyrazosulfuron-ethyl and butachlor can be enhanced if ethoxysulfuron or 2,4-D amine applied with these pre-emergence herbicides in a sequence. The results ensure that application of any of the above mentioned herbicide treatments could give better weed control in wheat under strip tillage system without sacrificing wheat yield and by rotating those herbicide treatments, herbicide resistance development can be delayed.