Vol. 12, Issue 8 (2023)

Author(s):
V Saravanan, K Sethuraman, VK Satya, K Eraivan Arutkani Aiyanathan, K Senthil, ML Mini and I Yesuraja

Abstract:
Onion twister blight disease is a major constraint in onion cultivation during the rainy season. The present study was carried out with the aim of studying the morphological characters of onion twister blight pathogen. Survey was conducted in major onion cultivating areas of Perambalur, Dindigul, Madurai and Virudhunagar districts, Tamil Nadu and percent disease incidence ranged from 34.44 and 78.88%. The infected plants of onion showed various symptoms, including chlorosis, leaf twisting, curling, the presence of acervuli in the neck region, and the development of slender bulbs. The pathogen isolated from infected leaves of onion exhibited a greyish white to grey mycelium, hyaline and septate. The pathogen produced cylindrical, hyaline conidia with a size ranging from 15 to 20μm in length and 4 to 7 μmin width. Isolated pathogens proved its virulence in symptom development and satisfied Koch's postulates during pathogenicity test. This provided conclusive evidence of the pathogen's role in causing the twister blight disease.