Interaction of the fungicide mancozeb and Rhizobium sp. in pure culture and under field conditions

Information on the compatibility of Rhizobium sp. with seed-protectant chemicals is controversial because of variations in the methods used and the lack of quantitative data. The present study was conducted to determine the influence of the fungicide mancozeb (ethylenebisdithiocarbamate), at recommended doses, on the growth, survival and symbiotic properties of Rhizobium sp. infecting peanut plants (Arachis hypogaea) under laboratory and field conditions. The results indicated that mancozeb decreased growth in pure culture by 50% of both Rhizobium sp. USDA 3187 and a strain isolated from peanut nodules. However, no differences were found in peanut seed yields under field conditions. These results suggest that the soil environment could reduce the probability of the direct, harmful effects of mancozeb on bacterial growth.