Evaluation of bio efficacy of plant extracts, bio agents and essential oils against Alternaria carthami (in vitro)

Safflower (Carthamus tinctorius L.) is impacted by both biotic and abiotic stresses, with fungi being the primary cause of major diseases followed by bacteria, viruses, and nematodes. Among fungal diseases Alternaria Leaf Spot, caused by Alternaria carthami (Chowdhary) is major concern. Most cultivated varieties of safflower are susceptible to leaf spot/blight. And for control fungicides are mostly used. However, increasing public concern and environmental risks are driving the search for alternative, eco-friendly disease management strategies. Thus this experiment is planned and conducted in vitro conditions with Completely Randomized Design (CRD) and 8 treatments replicated thrice to assess the bio-efficacy of plant extracts, bio agents and essential oils against A. cartham using the dual culture technique, at Department of Plant Pathology, College of Agriculture, Pune 2022-2024. The results shows the bioagents T. viride was found to be the most effective, recorded least mycelial growth 13.67 mm and the highest growth inhibition 84.81 %. The second and third bioagents were T. harzianum and T. hamatum which recorded 20.60 mm and 29.41mm mycelial growth and showed 77.11 % and 67.32 % mycelial growth inhibition respectively. Among the seven botanicals, garlic was the most effective, with a 90.66 % inhibition, followed by ghaneri at 89.44 % and in essential oil, citronella oil (5.50 mm) was the most effective tested at 1000 ppm, achieving the highest inhibition of A. carthami radial growth, followed by the garlic oil (10.33mm).