Native bioagents of the North-eastern Himalayas for the management of Sclerotinia sclerotiorum (Lib.) de Bary

Meghalaya, a biodiversity-rich state in North-eastern India, is increasingly facing challenges from soil-borne pathogens, particularly Sclerotinia sclerotiorum (Lib.) de Bary, which has emerged as a major threat to vegetable cultivation in the hill farming systems. This fungus causes significant yield losses and its management through chemical means poses risks to soil health, the environment and long-term sustainability. The present study explored 11 native Trichoderma spp. and 5 plant growth-promoting rhizobacteria (PGPR) isolates for the management of S. sclerotiorum affecting various horticultural crops in the state. The Trichoderma and PGPR isolates obtained from the rhizosphere of different crops grown under the Umiam circle of Ri Bhoi district, Meghalaya, were characterised based on morpho-cultural, biochemical, internal transcribed spacer (ITS) and 16s region amplification, respectively. The potent Trichoderma isolates UM-5, UM-10 and the PGPR isolate (PGPR-4) were established as Trichoderma asperellum Samuels, Lieckf. & Nirenberg, Trichoderma harzianum Rifai and Bacillus subtilis (Ehrenb.) Cohn. In vitro evaluation of the isolates showed that UM-5 and UM-10 exhibited 78.4 %, 87.3 % inhibition, while PGPR-4 showed 67.0 % inhibition of the target pathogen, along with functional and plant growth-promoting attributes in the range higher than 50 % for most of the parameters. The potential biocontrol agents (UM-5, UM-10 and PGPR-4) can be employed alone and in combination with other bio inputs for holistic and eco-friendly management of the soil-borne pathogen.