Comparative Efficacy of Plant Extracts and Trichoderma harzianum against Purple Blotch (Alternaria porri) of Garlic (Allium sativum L.)

Garlic (Allium sativum L.), commonly known as "Lahsun," is a crucial spice from the Amaryllidaceae family and is the second most widely cultivated Allium species after onions. Alternaria porri inflicts severe damage on crops and significantly reduces yields, remaining a major concern for farmers and agricultural researchers. This study is aimed to evaluate the Comparative efficacy of plant extracts and Trichoderma harzianum against purple blotch (Alternaria porri) of garlic (Allium sativum L.). A laboratory and field experiment were conducted at the research plot of the Department of Plant Pathology, Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh in rabi season of 2023-24 to evaluate the effect bio- agents and plant extracts against purple blotch of garlic and to increase the growth parameters. A total of eight treatments namely Trichoderma harzianum@10%, Lantana camara leaf extract@10%, Eucalyptus leaf extract@10%, Tulsi leaf extract @10%, Datura leaf extract @10%, Neem leaf extract @10% including control as non-treated check and Mancozeb+Tebuconazole @0.2% as a treated check were replicated three times. Among all the tested treatments, Eucalyptus leaf extract was found significantly superior over control along with all other treatments which recorded minimum disease intensity and maximum yield followed by Neem leaf extract. In in vitro conditions, the bio agent Trichoderma harzianum were tested by dual culture method and plant extracts were evaluated by poison food technique. In the present study, Trichoderma harzianum among the bio-agent and Neem leaf extracts among the plant extracts shows maximum mycelial growth inhibition as compared to control. Evaluating plant extract contributes to the scientific validation of traditional knowledge and combining biological control with botanicals can be an effective component of IDM programs, reducing the need for synthetic inputs.