Experiments on mechanical weed control in saffron crops in Spain

In the Jiloca valley (Teruel, Spain) saffron (Crocus sativus) is attracting attention because of its high quality and the growing demand in the gourmet market. To increase production the phytosanitary status needs to be guaranteed as well as the mechanization of the basic agronomic practices, especially weed control operations. Saffron is a perennial crop and weeding is especially important after flowering in mid of October until May when the aerial part disappears. Eight field trials were established to test the effect of flextine harrow, torsion and finger weeders. Torsion and finger weeders were difficult to adjust due to compact soils and steering problems. Efficacy for these tools was higher than 80% in two out of 12 occasions, only, while the flex-tine harrow exceeded this value in 7 occasions out of 18. The flextine harrow did no require adjustments on the row and could be used in an aggressive position because of the 20 cm plantation depth of the corms. Weeds including the Poaceae Lolium rigidum could be effectively controlled with the flextine harrow provided climatic conditions allowed treating immediately after flower harvest. Saffron flower and corm density were reduced by more than 40% after 3 cropping seasons without weed control compared to harrowing. Only slight differences were found in bulb size being higher for the harrowed plots. The use of the flex-tine harrow is highly recommended to reduce yield losses as well as to avoid weeds hosting viruses.