Weed management strategies based on cover crops, mulches and bioherbicides in Mediterranean vineyards
Climate emergency is forcing the search of more sustainable strategies for the soil management in vineyards. In this sense, the control of weeds is a real challenge due to their high expansion capacity and to caused yield losses. Cynodon dactylon (L.) Pers. and Conyza bonariensis (L.) Cronquist are among the most competitive and harmful weed species that can be find in vineyards. Traditionally, tillage has been the most widely used method for weed management, although its use increases the risk of erosion, decreases organic matter and leads to a high carbon footprint. On the other hand, the continuous use of synthetic herbicides has evolved herbicide-resistant biotypes and, due to their high toxicity, their use is widely questioned. This thesis dissertation proposes different alternatives for weed management in vineyards, both on the alleyways and in the under-vine zone. In order to manage weeds, the aim of the experiments carried out was to evaluate and provide new knowledge about the possibility of establishing cover crops, organic mulches or applying herbicide substances of natural origin in a sustainability-production balance. The first part of this thesis focuses on cover crops. On one hand, the emergence of 18 species, susceptible to be used as cover crops in vineyards, was modelled. The inclusion of photoperiod and solar radiation was essential for developing a single successful model for each species, applicable throughout the year. On the other hand, the usefulness of sowing different species as cover crops during winter and terminating them with the roller-crimper was evaluated. The termination method with roller-crimper proved to be more successful than the usual shredding for containing C. dactylon infestations. Regarding the under-vine zone, the use of alternative compounds such as potassium metabisulfite alone or mixed with pelargonic acid, and the mixture of humic and fulvic acid, showed to be effective for the control of C. bonariensis, although applying them in an early phenological stage of the weed is essential to obtain maximum effectiveness. Finally, the use of organic mulches, such as straw of different species, chopped pine wood or almond shell, was effective for under-vine weed control as long as high soil cover was achieved with the mulches. In this sense, the last two mulches (pine and almond) showed to be much more persistent and effective over time, while an increase of several parameters of vine vigour, including yield, was observed when comparing these mulches with traditional methods like tillage through in-row tiller or mower passes.