Evaluation of Fungicides Against Rhizoctonia bataticola (Taub) Butler Causing Dry Root Rot of Groundnut and Their Compatability with Trichoderma asperellum

The efficacy of four systemic and combination fungicides, namely Carbendazim 12% + Mancozeb 63% WP, Tebuconazole 25% WG, Hexaconazole 4% + Zineb 68% WG, and Tebuconazole 50% + Trifloxystrobin 25% WG, against Rhizoctonia bataticola, the causal agent of dry root rot in groundnut was evaluated using the poison food technique. Among the tested fungicides, Hexaconazole 4% + Zineb 68% WG exhibited the highest efficacy, with 100% inhibition of mycelial growth at all concentrations tested. Tests of compatibility of these fungicides with Trichoderma asperellum revealed that Hexaconazole 4% + Zineb 68% WG caused 38.88% of growth inhibition in T. asperellum while the other fungicides tested were totally incompatible with100 percent inhibition.

Investigations on fungicidal sensitivity of trichoderma spp and sclerotium rolfsii (collar rot pathogen) in crossandra.

Crossandra is an important flower plant of our country earning a lot of revenue and trade. Of different diseases affecting crossandra cultivation, collar rot induced by Sclerotium rolfsii Sacc. is an important soil borne disease causing devastating losses. In the present study, the sensitivity of the collar rot pathogen was investigated. Also the compatibility of fungal biocontrol agent, Trichoderma spp. with these fungicides was worked out to for further devising Integrated Management strategies for collar rot disease. Four fungicides, viz., captan 50% WP, propiconazole 25% EC, thiophanate-methyl 70% WP and thiram 75% SD were evaluated at five different concentrations against collar rot pathogen, S. rolfsii. Further, the compatibility of these fungicides and the antagonist Trichoderma isolate-1 (T1). Results indicated that the fungicides, propiconazole, thiram and captan have significantly reduced the mycelial growth of test pathogen over control. Maximum inhibition was with propiconazole (100%), followed by thiram (81%) and captan (78%). Results on compatibility of Trichoderma spp. with these fungicides revealed that the bioagent was highly compatible with thiram (32% growth inhibition), followed by captan (47.5%). However, the Trichoderma isolate is not compatible with thiophanate methyl (88% growth inhibition) and propiconazole (100% growth inhibition). The Trichoderma isolate-1 (T1) and the fungicide, thiram were selected for further studies to devise integrated management strategies against collar rot disease.