Control of peanut root and pod rots diseases using certain bioagents

Abstract

To evaluate the potential of certain bacterial and fungal bioagents against Macrophomina phasolina, Rhizoctonia solani and Fusarium oxysporum which causing peanut root and pod rots diseases. Thirty three fungal isolates obtained from infected plants showing typical symptoms of peanut root and pod rot, collected from different localities in Assiut, Sohag and Minia governorates, Egypt were identified as R. solani, M. phaseolina, F. solani, Aspergillus niger, A. flavus,  F. moniliforme, F. equesti and F. semitectum. Pathogenicity tests showed that M. phaseolina No. 4 recorded was the most pathogenic as incited root-rot and pod rot on the tested peanut cultivars NC followed by R. solani No. 6 and F. solani No. 7. Under laboratory conditions, twelve isolates of bacterial bioagents i.e Bacillus subtilis (BS1 and BS2), Bacillus megaterium (BM1 and BM2), Penibacillus polymyxa BP, Pseudomonas fluorescens (PF1 and PF2) and Azotobacter spp. (AZ1, AZ2, AZ3, AZ4 and AZ5), as well as, six isolates of Trichoderma spp. (T5, T7, T8, T9, T10 and T34) were tested to study their effects against the mycelial growth of the causal pathogens isolates i.e. M. phaseolina No. 4, R. solani No. 6 and F. solani No. 7. In vitro, our results showed that seven bacterial isolates (B. subtilis BS1, B. megaterium BM2, B. polymyxa BP, P. fluorescense (PF1 and PF2), Azotobacter spp. (AZ2 and AZ5)) and three isolates of Trichoderma spp. (T7, T10 and T34) gave the highest significant antagonistic effects against the test pathogens. The ten bioagents isolates which exhibited the best inhibition to the pathogenic fungi in vitro were tested in vivo during 2019 and 2020 growing seasons and the results revealed that Trichoderma spp. T34, B. subtilis BS1, P. polymyxa BP, Azotobacter spp. AZ2, B. megaterium BM2 and Trichoderma spp. T10, which tested against M. phaseolina, R. solani and F. solani, gave the highest reduction of both peanut root and pod rots diseases.