Biodegradable mulching spray for weed control in the cultivation of containerized ornamental shrubs

Weed control represents a major issue in plant cultivation in containers. Manual weed control is very expensive and the use of chemical herbicide or plastic mulch flms has a large environmental impact. The aim of this study was to test the efcacy of an experimental biodegradable chitosan-based mulching spray in controlling weed growth in containers. This research also studied the efect of this mulch on the growth of Viburnum lucidum Mill. plants to test for possible phytotoxic efects. The study compared a total of six treatments derived from three types of weed control (no weed control; herbicide, oxadiazon; mulching spray) applied in containers either flled only with the sterile substrate or flled with the sterile substrate and then artifcially inoculated with seeds of the weed species [Sonchus asper (L.) Hill subsp. asper and Epilobium montanum L.]. The mulch controlled the weeds efectively for more than 2 months after its application even under severe weed infestation. The mulching spray controlled the emergence of S. asper more efciently than E. montanum plants, probably because the latter has a stronger capacity to penetrate the mulch flm during emergence. Three months after its application, the mulch started to degrade and this allowed some weeds to emerge in the containers, but, in general, the mulch performed better than the herbicide. The chitosan-based mulch did not have any negative efective on the growth of V. lucidum plants.