Reduced-Rate Herbicide Combinations for Living Mulch and Weed Management in a Vegetable Crop
There is increasing interest in improving the sustainability of our farming systems. Living mulch systems can contribute to these advancements by increasing diversity and resource use efficiency, eliminating inter-row cultivations, and by reducing soil erosion by rapidly providing soil cover. However, competition with the cash crop and unreliable weed control are major challenges for the adoption of living mulches. The goal of this research was to evaluate reduced rates of herbicides as a tool for alleviating these drawbacks. It was hypothesized that the combination of living mulches and herbicides can complement each other to reduce both living mulch vigor and herbicide inputs, without compromising weed control efficacy or crop yield. Field trials were conducted during three growing seasons (2014-2016), at the Homer C. Thompson Vegetable Research Farm, in Freeville, NY, using sesbania and sunnhemp as living mulches in tomato. In 2015, there was a positive relationship between tomato yield and living mulch biomass. This relationship, however, was negative in 2016. These contrasting results were likely due to competition for water, with wet conditions occurring in 2015 and dry conditions occurring in 2016. Compared with the untreated living mulch check, the herbicide treatments reduced tomato yield losses by up to 71% in 2015 and 51% in 2016. Up to 2.5 tons ha 1 of dry matter was generated by the living mulches during both 2015 and 2016, with an average ground cover of 65% in 2015 and 85% in 2016. Weed biomass was reduced by as much as 97% by the living mulch-herbicide combinations. Our findings suggest that including reduced-rate herbicide applications in living mulch systems is effective in suppressing weeds without compromising living mulch biomass, soil cover, or crop yield, thereby enhancing the overall feasibility of living mulch systems.