Biocontrol Fitness of an Indigenous Trichoderma viride, isolate NRCL T-01 against Fusarium solani and Alternaria alternata causing Diseases in Litchi (Litchi chinensis)

Abstract

Biological control represents an important approach to manage plant diseases. Blights of leaf, panicle and fruits caused by Alternaria alternata and the wilt caused by Fusarium solani are important diseases of litchi. Hence, as an alternative to chemical fungicides, biological control by Trichoderma spp. to manage pathogens of litchi was explored. The aim of this study was to isolate native Trichoderma spp. from litchi orchard ecosystem and to evaluate antagonistic potential and its biological fitness so as to develop a commercial formulation for field application to manage litchi diseases. The results showed that out of nine isolates of Trichoderma spp. isolated from litchi rhizosphere soil collected from different litchi orchards located in Muzaffarpur, Bihar the Trichoderma viride isolate NRCL T-01 showed highest antagonistic activity in dual culture bioassay against litchi pathogens, A. alternata (70.5% inhibition) and F. solani (60.9% inhibition). The volatile and non-volatile compounds produced by the isolate could effectively inhibit both the pathogens. It could grow well at temperature between 15 to 45 °C, tolerated pH between 4.0 to 7.0 and high salt stress (0.25-1.50 M NaCl). The talc based formulation of the T. viride isolate NRCL T-01 effectively controlled litchi wilt pathogen F. solani on challenge inoculation in glasshouse condition as well as naturally affected litchi trees in orchards. Additionally, the isolate showed good plant growth promotion activity acting as a biofertilizer and helping air-layers to establish better in fields. Further study is being conducted to validate the potential as a commercially-viable product under farmers’ field conditions.