Using Ficus retusa L. leaf residue for weed control in field grown green beans

ABSTRACT Given the need to minimise the environmental impact of synthetic agrochemicals in agroecosystems and to increase the sustainability of production systems, it is necessary to identify alternative methods for weed management and crop protection. Regular pruning of evergreen trees, including Ficus retusa L., can provide large quantities of leaf litter and this study aimed to evaluate the use of this leaf residue in a horticultural production system. The effects of using the residue as an organic soil amendment were assessed, including the potential of the residue to control weeds in green beans (Phaseolus vulgaris) crop. Three application rates of F. retusa leaf residue (250, 500 and 1000 g m−2) were applied to the soil at two locations. At both sites, the treatments significantly reduced the density and the biomass of several weed species in a dose- and weed species-dependent manner. The total weed density and weed biomass were also substantially reduced, but there were no effects on the growth or the yield of the P. vulgaris in the treated plots. The application of the leaf residue increased soil organic carbon and some macronutrients, including available nitrogen and potassium. High-performance liquid chromatographic (HPLC) analysis revealed the presence of phenolic and flavonoid compounds in the F. retusa leaves and the reduction of weeds may be attributed to the release of phytotoxins from the residue. Overall, the results suggested that F. retusa leaf residue can be used as part of the weed management strategy to control weeds in P. vulgaris crops.