Integrated Weed Management of Moldavian balm (Dracocephalum moldavica L.) Using Reduced Rates of Herbicides and Straw Mulch

In order to evaluate the integrated weed management of Moldavian balm (Dracocephalum moldavica L.) an experiment was conducted based on randomized complete block design with three replications in Agricultural Research Farm of University of Tabriz, in 2016. The experimental treatments were different herbicide rates including 100 and 50% of recommended dose of trifluralin and pendimethalin (2.5 and 4.5 L.ha-1, respectively) alone and integrated with straw mulch (5 t ha-1). The application of herbicides combined with straw mulch had higher efficacy than herbicide treatments without mulch in weeds control. The effect of trifluralin in weed biomass reduction was greater than that of pendimethalin. The highest weed biomass reduction (83.8%) was observed in trifluralin 100% + straw mulch. All growth and yield traits of Moldavian balm were significantly affected by weed management treatment except essential oil percentage. The highest flowering head yield of Moldavian balm (948 kg ha-1) was observed in trifluralin 100% + straw mulch treatment. Also the highest essential oil yield of Moldavian balm was achieved in trifluralin 100% + straw mulch (6.3 kg ha-1) and the lowest one was achieved in pendimethalin 100% (2.06 kg ha-1). Generally application of trifluralin 100% + straw mulch had suitable weed control and increased the growth traits and essential oil yield of Moldavian balm. The management treatment of trifluralin 50% + straw mulch had the same weed control efficacy and essential oil yield as trifluralin 100% and could be suitable replacement for this treatment along with reduction of herbicide application and integrated weed management of Moldavian balm.