CONICET | Buscador de Institutos y Recursos Humanos

Weeds produce important crop yield losses. Among the methods for weed control, herbicide use is the most common. Nowadays, optimization of herbicide application is pursued to mitigate environmental impact, reduce the appearance of herbicide-resistant weed populations, and minimize the cost/benefit ratio. This work proposes a conceptual operational planning model aimed to calculate the optimal application times of herbicides along an agronomical season in order to rationalize the frequency of applications with respect to experience-based approaches and to maximize the economical benefit of the activity. The system wheat-wild oat (Triticum aestivumAvena fatua), typical of the semiarid region of Argentina, is used as a case study. The proposed model uses Cousens hyperbolic equation to describe crop yield loss due to weed competition and makes use of the concept of time-density equivalent. To simplify the analysis and represent extreme cases, constant weed emergence patterns (2, 8 and 15 plants/m2/day) were assumed. In all scenarios an herbicide was applied in crop pre-emergence to eliminate the first emerging seedlings that would have a large impact on the final crop yield. In the last two cases the model also recommended a second application immediately after the end of crop susceptibility period. The GAMS platform and the solver BARON were used to program and solve the resulting mixed integer non-linear model. It should be mentioned that an optimal scheme of herbicide application that maximizes crop yield may not be compatible with a conservationist strategy towards minimizing the environmental impact and delaying the appearance of herbicideresistant biotypes.Therefore, a multi-objective approach should be adopted to consider the tradeoff between these

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