HERBICIDE OPTIONS FOR EFFECTIVE WEED MANAGEMENT IN ZERO-TILL WHEAT, MAIZE AND DIRECT-SEEDED AMAN RICE UNDER WHEAT MUNGBEAN-RICE AND MAIZE-MUNGBEAN-RICE CROPPING SYSTEMS HERBICIDE OPTIONS FOR EFFECTIVE WEED MANAGEMENT IN ZERO-TILL WHEAT, MAIZE AND DIRECT-SEEDED AMAN RICE UNDER WHEAT MUNGBEAN-RICE AND MAIZE-MUNGBEAN-RICE CROPPING SYSTEMS

Abstract

The information on the efficacy and economics of different pre-and post-emergence herbicides used alone or sequentially in the conservation agriculture (CA)-based zero-till (ZT) wheat, maize and direct seeded (DSR) rice production system is still sporadic or lacking in Bangladesh. In the context, an observation entitled ‘Herbicide Options for Effective Weed Management in Zero-Till Wheat, Maize and Direct-Seeded Aman Rice under Wheat-Mungbean Rice and Maize-Mungbean-Rice Cropping Systems’ was conducted in consecutive two years of 2017-2018 and 2018 2019. This observation consisted of three experiments; Expt. 1. Efficacy and Economics of Different Post-Emergence Herbicides for Controlling Weeds in Wheat under Zero-Till Condition; Expt. 2. Efficacy and Economics of Different Pre-and Post-Emergence Herbicides for Controlling Weeds in Maize under Zero-Till Condition and Expt. 3. Efficacy and Economics of Different Pre-and Post-Emergence Herbicides for Controlling Weeds in Zero-Till Direct Seeded Aman rice. Treatments of the first experiment were: ready-mix formulation (Sulfosulfuron + Metsulfuron); ready-mix formulation (Mesosulfuron + Idosulfuron); Pinoxaden; ready-mix formulation (Carfentrazone + Isoproturon); Pinoxaden + Metsulfuron; Pinoxaden + Carfentrazone; Halosulfuron; Halosulfuron + Pinoxaden; Weedy check and Weed free. After two years of observation, the results of the study revealed that the highest yield of ZT-wheat (4860 kg ha-1) was recorded in weed-free treatment in the first season, which was statistically similar to Pinoxaden + Metsulfuron in both years (4643.33 and 5683.33 ha-1) and the lowest grain yield (2595 and 3880 kg ha-1) was recorded in weedy check plots. From an economic point of view, the maximum net benefit (121386 Tk ha-1) in the first year was recorded in Pinoxaden + Metsulfuron treatment, but in the second season, the maximum benefit (212578 Tk ha-1) was recorded in Halosulfuron + Pinoxaden applied plot. In 2nd experiment, treatments were two pre-emergence herbicides (Pendimethalin and Atrazine) and a control (without pre-emergence herbicide) and five post-emergence herbicides (i.e., Atrazine; Tembotrione; Halosulfuron; Tembotrione + Atrazine and Halosulfuron + Atrazine) and a control (without post-emergence herbicide). After two years of observation, the findings of the study revealed that sequential use of pre- and post-emergence herbicides significantly influenced the grain yield of ZT-maize by effectively controlling all types of weeds. In the first year, the highest grain yield was recorded in the sequential application of Pendimethalin applied immediately after maize seeding with post-emergence herbicides Tembotrione + Atrazine (13.9 t ha-1) applied at 15 DAS. However, in the second year, the sequential application of Atrazine applied immediately after maize seeding with post-emergence herbicides Tembotrione (17.2 t ha-1) applied at 15 DAS performed the best, followed by Atrazine as pre-emergence and Tembotrione + Atrazine (16.6 t ha-1) applied as post emergence and the lowest was recorded in the control plot (10.9 t ha-1). From the economic point of view, the maximum net benefit (two years’ averaged) was recorded from Pendimethalin & Atrazine (both applied as pre-emergence) and Atrazine (as post-emergence) (367807 & 362907 Tk. ha-1) applied plots, followed by Pendimethalin & Atrazine (both as pre-emergence) and Tembotrione + Atrazine (as post-emergence) (362582 & 363832 Tk.ha-1), while the minimum net benefit (258907 Tk. ha-1) was recorded in weedy check treatment. In 3rd experiment, treatments were two pre emergence herbicides (i.e., Pendimethalin and Oxadiazon) and a control (without pre-emergence herbicide) and five post-emergence herbicides (i.e., No-post-emergence; Bispyribac Sodium; Bispyribac Sodium + Pyrazosulfuron; Fenaxoprop + Ethoxysulfuron and Fenoxoprop fb Halosulfuron. Results of the two years of the study showed that all types of weeds were effectively controlled by the sequential use of pre-and post-emergence herbicides. Considering plant growth, yield and yield attributing of ZT DSR Aman rice, all parameters were significantly influenced by pre emergence herbicides (Pendimethalin & Oxadiazon) applied immediately after rice seeding followed by post emergence herbicides (sole application of Bispyribac-sodium, and combination of Bispyribac-sodium + Pyrazosulfuron, Fenaxoprop + Ethoxysulfuron and Fenoxoprop fb Halosulfuron) applied as post-emergence. Among these herbicides, the highest grain yield in both years was found in the sequential use of pre-emergence herbicide Pendimathalin followed by the application of post-emergence herbicides ‘Bispyribac Sodium + Pyrazosulfuron’ (5.3 t ha-1 in the first year) and ‘Bispyribac-sodium’ (5.2 t ha-1 in second year). From the economic point of view, the maximum net benefit was recorded in the plot, where Pendimethalin was applied as pre-emergence in combination with Bispyribac-sodium + Pyrazosulfuron (two years’ average 100179 Tk. ha-1) applied as post-emergence, followed by Oxadiazon as pre-emergence in combination with the sole application of Bispyribac-sodium (two years’ average 95873 Tk. ha-1). Based on the two years of yield and the economic benefit of these three observations the combination of herbicides Pinoxaden + Metsulfuron and Halosulfuron + Pinoxaden may be recommended for weed control in ZT wheat. In the case of ZT-maize, the sequential application of Pendimethalin and Atrazine applied as pre-emergence immediately after sowing of maize seeds in combination with sole Atrazine or in combination with Tembotrione + Atrazine as post-emergence may be recommended for weed control in the ZT-maize. While, in ZT DSR Aman rice, the sequential application of Pendimethalin and Oxadiazon as pre-emergence immediately after sowing of rice seeding in combination with Bispyribac + Pyrazosulfuron or Fenaxoprop + Ethoxysulfuron or sole application of Bispyribac Sodium as post-emergence may be recommended for weed control in ZT-DSR Aman rice.