Isolation and in vitro screening of native Trichoderma isolates against economically important pathogens of Japanese Mint (Mentha arvensis)

Abstract

Japanese mint (Mentha arvensis) is a common edible aromatic herb of considerable economic importance and the crop is reported to be infected by several fungal pathogens. As Mentha contains essential oil which is used in pharmaceutical industries, the use of biocontrol agents is considered as a potential eco-friendly component in plant disease management. Hence an investigation was conducted in the Department of Plant Pathology, RPCAU, Pusa, Bihar to evaluate native Trichoderma isolates against two economically important foliar pathogens of Japanese Mint (Mentha arvensis) i.e., Alternaria alternata and Curvularia lunata. Total 7 Trichoderma isolates were isolated from the rhizosphere of various medicinal plants and those were categorized based on their morphological characteristics. Initially, all Trichoderma isolates developed whitish mycelium which later differed from light to dark green in color and the growth rate ranged from 11.25 mm to 18.00 mm per day. During the evaluation of antagonistic activity, all the Trichoderma isolates significantly reduced the growth of Alternaria alternata and Curvularia lunata mycelia in vitro condition. Among the seven isolates, Tr6 recorded the highest inhibition of Alternaria alternata (65.66%) and Curvularia lunata (45.04%) followed by Tr3 which showed 57.00% and 40.32% mycelial growth inhibition of Alternaria alternata and Curvularia lunata respectively after 168 hours of incubation. Tr6 isolate also exhibited the highest biochemical activities viz., indole acetic acid, ammonia, and siderophore production. The results from the current investigation revealed that Tr6 isolate was found most potential in the suppression of pathogens growth as well as in the production of phyto stimulators. In future studies, this isolate can further be evaluated for successful management of diseases of Japanese mint (Mentha arvensis).