Toxicity of dicamba (2-methoxy-3,6-dichlorobenzoic acid) to Azotobacter vinelandii

The effect of dicamba was studied in N-free medium inoculated with Azotobacter vinelandii ATCC 12837. Nitrogen fixation was determined by acetylene reduction. Dicamba at a concentration of 500 micrograms/mL had a strong inhibitory effect on nitrogenase activity. However, no inhibitory effect on microbial respiration was detected.