Vol. 11, Special Issue 8 (2022)

Author(s):
S Siva Ramakrishnan, I Yesu Raja, K Eraivan Arutkani Aiyanathan, S Merina Premkumari, N Rajinimala and EG Ebenezar

Abstract:
Onion (Allium cepa var. aggregatum) is a prominent bulbous vegetable crop grown worldwide for its pungency and flavour. Onion production is affected by various fungal and bacterial diseases. Among the fungal diseases affects onion, the twister blight of onion (Colletotrichum gloeosporioides) causes yield loss of 20 to 30 per cent. A survey was conducted to assess the incidence and severity of the twister blight disease in six onion growing districts of Tamil Nadu. The highest twister blight disease incidence (48.57 PDI) was recorded in Kurippangulam village of Tirunelveli district. The lowest disease incidence (28.00 PDI) was recorded in Sankarankovil of Tenkasi district. During the survey ten isolates (IS 1 to IS 10) of Colletotrichum gloeosporioides were isolated from the diseased samples. Among these isolates, Kurippangulam isolate (IS 1) was found to be the most virulent.