Isolation, cultural, morphological characterisation and pathogenicity of tomato damping-off caused by Pythium aphanidermatum

Tomato is one of the most important vegetable crop that grown all over the world. The cultivation of tomatoes holds immense significance in the agriculture industry, yet it grapples with various challenges, including the emergence of diseases caused by fungi. One such disease is damping-off, primarily caused by Pythium aphanidermatum, leading to substantial declines in crop yields. A comprehensive survey was conducted across the key tomato cultivation districts of Tamil Nadu: Dharmapuri, Cuddalore, and Krishnagiri. The study focused on gathering 10 distinct isolates of Pythium sp., designated as Pa1-Pa10, for subsequent examination. Through a meticulous analysis of their morphological characters and growth patterns, these isolates were successfully identified as Pythium aphanidermatum. The investigation revealed significant diversity and variations in both morphological features and cultural behaviours among the isolates. Pathogenicity assessments unveiled that isolate Pa9 displayed the highest virulence within the group, with a disease incidence rate of 34.88%. In contrast, the lowest disease incidence rate of 9.28% was recorded in Pa6 Keerapalayam village of Cuddalore district.