Comparison of three chemical control strategies for Avena sterilis ssp. ludoviciana

The relatively high cost of Avena sterilis ssp. ludoviciana herbicides makes necessary the development of application strategies that maximize the efficacy with a minimum cost. Three herbicide strategies (spray at full and half doses and patch spray adjusting the doses to A. sterilis density) were compared in relation with control efficacy and crop yield in a winter barley field during three years. The results varied slightly within the years but, in general, the highest control levels and barley yields were obtained with the treatments at full dose. Using half doses reduced both A. sterilis control and barley yields. This effect was mainly attributed to the poor performance of low doses with high weed densities. The site-specific treatments resulted in the highest variability in the control and yield levels, with some control failures in areas of low density of A. sterilis. Barley yields were more affected by the zone effect (position of the plot within the field) than by the weed density effect. This fact was probably attributed to the relatively high heterogeneity in soil fertility within the field. Although the most profitable strategy in this specific situation was treating the whole field at full dose, this was probably due to the high percentage of the field infested by this weed. Different conclusions may be reached under different situations. © 2008 Elsevier Ltd. All rights reserved.