To explore bio-control options available for management of Siam weed, a survey was conducted during the year 2017-18 and 2018-19 in different districts of Tripura, India. During survey, symptoms of leaf blight were observed on leaves of Siam weed. Fungi isolated from infected sample on PDA media shows slow growth covering whole petri plate within 10 days. During incubation period fungal sporulation increases with increase in growth period. Identification of suspected causal agent was Phytophthora which was confirmed based on the morphology. Culture colonies of Phytophthora produce coenocytic hyphae, unbranched sporangiophores, ovoid or subglobose to globose hyphal swellings with an average diameter of ± μm. Pathogenicity tests were carried out for further confirmation. Based on morphological features, the fungus on Siam weed was identified as Phytophthora spp. Based on available reviews, this is the first incidence of report of Phytophthora spp. from Tripura under the family Asteraceae, causing Leaf blight on Siam weed. | Isolation and microscopic study of leaf spot of chromolaena odorata (Siam Weed) caused by Phytophthora spp. from Tripura
