Strategies for the control of Avena sterilis in winter wheat production systems in central Spain

Abstract

A bioeconomic model is described and used to investigate the agronomic and economic consequences of using a range of management strategies for the control of winter wild oats ( Avena sterilis L.) in cereal cropping systems representative of central Spain. The results of simulations indicated that growing winter wheat continuously with the annual application of herbicides may be the optimum strategy, resulting in acceptable wild oat populations and maximum economic benefits. However, the practice of wheat monoculture was only a valid option as long as herbicides were applied annually: spraying herbicides in alternate years failed to control wild oats adequately and resulted in major economic losses. The rotation of wheat with a fallow year, with no herbicides applied in either of the two years, may be a satisfactory low-cost alternative when wild oat infestation levels are low, but it is not valid when infestation levels are high. The strategy that combines the use of a fallow year with herbicide application in the wheat year resulted in optimum wild oat control and moderate profitability under all conditions. However, the net returns obtained were substantially lower than in the continuous wheat plus herbicide strategy. The sensitivity of the model to variation in various key parameters was tested: wheat yield level and fixed costs were the two parameters that had the largest effect on model output. In general, the effect of changing parameter values was more pronounced in continuous wheat systems than in wheat-fallow rotations