First evidence of Chaetomium globosum infection on Strobilanthes kunthiana.(Neelakurinji), a vulnerable and endemic species of tropical montane grassland in the Western Ghats, Kerala, India

Strobilanthes kunthiana (Nees) T. Anderson ex Benth., locally known as Neelakurinji, is a vulnerable and endemic species restricted to the tropical montane shola grassland ecosystems of the Western Ghats in southern India. It exhibits a gregarious 12-year mass flowering cycle and has substantial ecological and ecotourism value. Despite its conservation importance, the phytopathological and invasion threats are poorly documented. During field surveys 2022–2024 in Eravikulam National Park, leaf blight was detected in scattered Neelakurinji populations, with symptoms ranging from severe foliar necrosis to plant death. This study investigates the fungal associates of S. kunthiana and invasive plant co-occurrence across its habitats to support disease management and conservation. Fungal Pathogens isolated from infected plant material were characterized based on their morphological features and further confirmed through multi-gene phylogenetic analysis, including sequencing of the internal transcribed spacer (ITS1–ITS4), β-tubulin (tub2), and translation elongation factor 1-alpha (TEF1-α) gene regions. The causal organism was conclusively identified as Chaetomium globosum validated through Koch’s postulates. Further, in vitro assessments were conducted to evaluate the influence of different growth media includes PDA (Potato Dextrose Agar), SDA (Sabouraud Dextrose Agar), RB (Rose Bengal) and temperature regimes (15, 22, and 30°C) on the radial mycelial growth of the pathogen.