Efficiency and compatibility of Trichoderma spp. and Bacillus spp. isolates on the inhibition of Sclerotium cepivorum

Abstract

Application of different biological control agents may be a strategy to be used against white rot, caused by the fungus Sclerotium cepivorum. However, isolates effectiveness and compatibility must be previously evaluated in laboratory experiments. Thus, in this study we evaluated the effect of Bacillus spp. and Trichoderma spp. isolates on the inhibition of S. cepivorum mycelial growth. In addition, we also evaluated the compatibility among the most efficient isolates. In experiments with paired cultures, eight Bacillus spp. isolates (B01, B03, B10, B120, B570, B571, B854 and B934) and five Trichoderma spp. isolates reduced pathogen mycelial growth by 42-50% and 100%, respectively. Thermostable metabolites produced by B03, B571, B570 and B120 isolates limited S. cepivorum growth when added into PDA medium, while Trichoderma cultures did not have the same effect. Twelve out of 40 combinations between bacterial and fungal isolates were incompatible. Therefore, B03, B570, B571 and B854 Bacillus spp. isolates, and SF45, SF32 and SF311 Trichoderma spp. isolates reduce mycelial growth of S. cepivorum and are mutually compatible. In addition, they can be applied together for the management of white rot.