Use of plant water extracts for weed control in durum wheat (Triticum turgidum L. Subsp. durum Desf.)

The use of plant water extracts to control weeds is gaining attention in environmentallyfriendly agriculture, but the study of the effect that such extracts may exert on the yield of durum wheat is still unexplored. In 2014 and 2016, the herbicidal potential of several plant water extracts was field tested on durum wheat (cv Valbelice). In 2014, extracts obtained from Artemisia arborescens, Rhus coriaria, Lantana camara, Thymus vulgaris, and Euphorbia characias were used, whereas in 2016 only A. arborescens and R. coriaria were tested as "donor" plants. In both years, weed incidence was evaluated, together with the major yield parameters of wheat. None of the treatments (including chemicals) could eradicate weeds from the field. In 2014, dicots were in general prevailing in plots treated with extracts of E. characias, while monocots prevailed after treatments with L. camara and R. coriaria. In 2016, lower weed biomass and diversity level were found, and only Avena and Phalaris were detected at harvest time. Treatment with plant water extracts affected grain yields, but it seems likely that those effects are not due to the diverse incidence of weeds in treated and untreated plots, rather to some direct action exerted by allelopathic substances.