Economics of herbicide weed management in wheat in Ethiopia

Abstract

Effective use of herbicides for the control of annual grass and broadleaf weeds in wheat (Triticum aestivum L.) was not a reality in Ethiopia, until in recent years. This study aimed at evaluating different post-emergence herbicides against annual grasses and broadleaf weeds in wheat for selection and incorporation into an integrated weed management (IWM) system. The study was conducted at Kulumsa Agricultural Research Centre main station, Bekoji and Lole farm fields. Treatments included herbicides, namely, Mesosulfron methyl+Idosulfuron methyl sodium (liquid) 1 lit ha^-1 a.i. Pyroxsulam (liquid) 0.5 l ha^-1 a.i. hand weeding twice (30-35 and 55-60 days after emergence (DAE)); and a weedy check. Among the annual grass weeds, Snowdenia polystachya, Avena fatua, Bromus pectinatus, Phalaris paradoxa and Setaria pumila; and most broad leaf weeds like Polygonum nepalense, Guizotia scabra, Galinsoga parviflora and Gallium spurium were controlled with herbicide efficacy ranging from 75 to 100%. Mesosulfron methyl +Idosulfron methyl sodium, Pyroxulam and hand weeded twice plots outyielded the weedy check by 63, 58 and 53%, respectively. Maximum wheat grain yield (5,184 kg ha^-1), biomass (12,808 kg ha^-1), thousand kernel weight (48.55) and hectoliter weight (74.2) were obtained due to the application of Mesosulfron methyl+Idosulfuron methyl sodium. In addition, the herbicide had a yield advantage over Pyroxsulam, two hand weedings and the weedy check by 12, 21 and 63%, respectively. Application of Mesosulfron methyl + Idosulfuron methyl sodium (US$1,596.31 ha^-1) had the highest net field benefit compared to Pyroxsulam (US$1,379.21 ha^-1), two hand weeding (US$1,126.7 ha^-1) and weedy check (US$574.1 ha^-1) by 13.6, 29 and 64%, respectively. Moreover, the herbicide was also economically profitable to farmers, providing a marginal rate of return (MRR) of 1,737%. Sensitivity analysis (aMRR) also remained the most profitable even when the price of herbicide increased by 20%. Hence, Mesosulfron methyl +Idosulfuron methyl sodium at a rate of 1 lit ha^-1 is thebest herbicide for the effective control of annual grasses and broad leaf weeds in wheat and can be used as one of the component in Integrated Weed Management Program (IWM) in wheat fields.

Key Words: Idosulfuron methyl sodium, Mesosulfron methyl, Triticum aestivum