RÉSUMÉ
Leaf blight of the medicinal plants (Piper longum, Tylophora indica and Hibiscus subdariffa) is one of the most significant diseases that severely damage these crops throughout the year in West Bengal .So, management of this disease is essential at now. A few chemical fungicides and trichoderma isolates were tested under in vitro against the disease-associated pathogens in order to identify efficient chemical fungicides and bio agents.It was found that the trichoderma isolates T-2 and T-3 were effective against Colletotrichum gloeosporioides, whereas the isolates T-1 and T-2 were efficient in inhibiting the growth of the test pathogen better against Fusarium sp. and Sclerotium rolfsii.With a higher percentage of inhibition (77.60%), copper oxychloride was the most effective fungicide against Fusarium sp. Conversely, carbendazim and dithane m-45 were more effective against Sclerotium rolfsii and Colletotrichum gloeosporioides, showing 78.33% and 77.93% of inhibition, respectively, and less effective against Fusarium sp at higher concentrations (400 ppm). To determine whether or not these chemical fungicides and trichoderma isolates are effective under in vivo, they will be tested in the field against the corresponding pathogens associated with the disease.