Weed Control in Perennial Crops Using Hydromulch Compositions Based On the Circular Economy: Field Trial Results

Weed control in perennial crops is especially difficult in the first phases of crop establishment. Hydromulch is a pasty blend that hardens after application and has so far been used specifically for weed control for experimental purposes only. In this work we tested blends based on recycled paper, gypsum and lignocellulosic materials (wheat straw, rice husk and used mushroom substrate) applied in three different locations of Spain under peach, vine, almond and artichoke plantations compared with an untreated control, manual weeding and herbicide (only in artichoke). The most frequent weed species were annual and perennial forbs. Lower weed soil cover compared to the untreated control was still relevant between 333 and 456 days after mulching (DAM), depending on the trial. In the artichoke trial the weed control effect was similar to that obtained with herbicides until the end of the assessments. Annual forbs were satisfactorily controlled with hydromulches (highest for Lamium amplexicaule with an efficacy of 88% based on soil cover); mean efficacy of perennials such as Cyperus rotundus and Convolvulus arvensis was lower ranging between 30 and 74% efficacy depending on the trial. Multivariate analysis showed an increase in wind-dispersed species such as Conyza sp. and Lactuca serriola over time. The capacity of the mulches to reduce weed soil cover for around one year can be useful in crops where weed control is crucial during that time, such as in plant nurseries and new plantations. Future research could focus improving the durability of the mulches to extend this period.