ABSTRACT

The Canara circle in Karnataka state comes under South Western Ghats area is well known for agriculture, horticulture and forest eco-systems. It is becoming more important to manage soil borne pathogens as part of integrated disease management in this region. In this context the research was undertaken during 2019 to 2022 on “Exploration, molecular identification and evaluation of Trichoderma spp. in different eco-systems of Canara circle against soil borne pathogens”. In roving survey 42 rhizosphere soil samples were collected 250 g each from agriculture, horticulture and forest eco-systems respectively, in Haliyal, Mundgod, Siddapur, Sirsi, Yellapura, Ankola and Kumta taluks of Canara circle. Totally 27 Trichoderma isolates were isolated on Trichoderma selective medium, 11 isolates from forest, 9 isolates from horticulture and 7 isolates from agriculture eco-system. The majority of isolated Trichoderma isolates were 9.00 cm diameter after 96 hours of incubation. Based on in-vitro bio-efficacy study, Trichoderma isolate SST-37 recorded maximum mycelial growth inhibition against Sclerotium rolfsii, Phytophthora capsici and Fusarium solani (77.78, 76.30 and 76.48 %, respectively). Molecular identity of 27 Trichoderma isolates through ITS1/ITS4 primers confirmed that 16 isolates were Trichoderma yunnanense, 3 were T. crissum, 2 were T. lixii and 6 were T. atrobrunneum. However, efficient Trichoderma isolate (SST-37) was identified as T. yunnanense.
Talc, coffee husk and pesta granules based formulations of T. yunnanense SST-37 were prepared and evaluated under field condition against groundnut stem rot at ARS, Kumta, results revealed that T7 (seed treatment with talc formulation of T. yunnanense SST-37 @ 4 g/kg of seeds+soil application with pesta granules formulation of T. yunnanense SST-37 @ 2.5 kg/100 kg FYM ha-1 at 45 and 60 DAS) recorded the least PDI (4.00 and 6.67 at 60 and 85 DAS, respectively) and highest yield (34.84 q/ha) with benefit-cost ratio (1.51). Similarly, against basal foot rot disease of black pepper was carried during kharif 2020-21 at HREC, Sirsi. It was found that the vines treated with T6 (pesta granules formulation of T. yunnanense SST-37 @ 50 g vine-1, 1 kg of neem cake vine-1 as soil application and foliar spray with potassium phosphonate @ 3 ml l-1 during June and August month at 45 days interval) performed best in reducing per cent leaf infection (8.41 and 11.65), yellowing index (1.39 and 4.17), defoliation index (5.56 and 12.50) and recorded yield of 13.90 q/ha and benefit-cost ratio of 2.89. Whereas T5 (coffee husk formulation of T. yunnanense SST-37 @ 50 g vine-1, 1 kg of neem cake vine-1 as soil application and foliar spray with potassium phosphonate @ 3 ml l-1) was next best treatment. The pot experiment was conducted against root wilt disease of malabar neem during kharif 2020-21 at HREC, Sirsi and found that organic based treatment T5 (soil application with the coffee husk formulation of T. yunnanense SST-37 @ 2 g/kg of potting mixture + pesta granules formulation of T. yunnanense SST-37 @ 2 g/kg of potting mixture) applied twice at 45 days interval stands best in reducing disease (12.22 and 14.44 PDI, respectively).