Title: Weed communities in apple orchards under organic and conventional fertilization and tree-row management
Abstract: Weed control in apple orchards to reduce competition for water and nutrients is basic to avoiding the negative impact of weeds on tree performance. A two-year study was conducted in three orchards to assess the effect of two strategies of fertilization (organic and chemical) and three tree-row management systems (herbicide, tillage and straw mulching) on weed communities, focusing on floristic and functional traits. Tree-row management had a strong impact on the weed community, affecting the overall weed cover, the response of particular species and the occurrence of weeds grouped according to functional traits. In contrast, the effect of the fertilization strategies on all those parameters was lower, even non-existent. Herbicide and mulching hampered weed establishment more effectively than tillage. Tillage favoured therophytes whereas herbicide favoured hemicryptophytes, as a result of the different way these strategies keep the soil free of weeds and the impact they have on the soil. Mulching was associated with a decreased proportion of therophytes at the expense of hemicryptophytes. Cryptophytes were not affected by the treatments. Distribution of graminoids and forbs was affected by both experimental factors, but only in one orchard, so that this classification into weed classes was less predictive than lifeform as a functional trait to explain changes in the weed community associated with agricultural practices. The results of our research showed that tree-row management in apple orchards affects weed communities not only from a floristic but also from a functional point of view. This functional approach allowed us to identify functional traits related to management practices and will allow the prediction of the effects of vegetation management on a wider scale. [M. Miñarro (2012). Weed communities in apple orchards under organic and conventional fertilization and tree-row management. Crop Protection,39, 89–96. dx.doi.org/10.1016/j.cropro.2012.04.002]
Keywords: Mulching; Tillage; Herbicide; Life forms; Functional traits