Controlling arable weeds with natural substances as bio-based herbicides

Today farmers manage arable weeds with chemical tools or mechanical tillage practices. While the heavy reliance on synthetic herbicides in conventional arable farming is under discussion, the environmentally driven trend towards reduced tillage as a climate-smart agricultural practice becomes more prominent. These trends demand for alternative control methods of weeds. This greenhouse study investigates the control of 21 arable weeds with four natural substances. The experimental setup compared an untreated control with four natural substances (acetic, citric and pelargonic acid and magnesium chloride), and glyphosate was used as the common active ingredient for stubble and presowing herbicide applications. The level of necrotisation (0-100%) was used to assess the efficacy of herbicide treatment. The efficacy differs substantially among the bio-based herbicides. For all natural substances, pelargonic acid has the highest mean efficacy for controlling the weeds tested in this experiment. For most weeds, however, the efficacy of natural substances is much lower compared to glyphosate. Nevertheless, the results indicate that natural substances as bio-based herbicides have the potential to offer an increased target specificity and rapid degradation in the soil. We found a high efficacy of pelargonic acid for controlling Brassica napus.