In vitro evaluation of fungicides and botanicals against Alternaria tagetica causing blight of marigold

The present study delved into the integrated management of Alternaria blight, a major threat to marigold (Tagetes erecta L.) cultivation, caused by Alternaria tagetica. The experiment was conducted in the department of floriculture and landscaping, Punjab Agricultural University, Ludhiana during 2022 and 2023. Efficacy of six fungicides and botanicals was evaluated against Alternaria tagetica under in vitro conditions. Tebuconazole+trifloxystrobin gave maximum inhibition (100, 92.22, 89.63, 86.67, 85.56 %) followed by Azoxystrobin (100, 91.11, 82.22,76.67,70.37%),Tebuconazole (100, 90.00, 79.63, 75.19,64.44%),Difenoconazole (100,86.67,78.00,72.96,59.96%) and Metiram (90.74,82.96, 77.80,59.63, 54.45%) at 400,200, 100, 50 and 25 ppm concentration, respectively. Minimum inhibition (69.63, 64.81, 52.22, 37.41,29.26%) was observed in Chlorothalonil at all the five concentrations. Among the six botanicals tested Allium sativum, Azadirachta indica and Moringa oleifera showed strong antifungal activity with 78.89, 69.26 and 67.04 percent respectively at 2000 ppm. Minimum fungal inhibition was observed by Terminalia arjuna (35.14%). Overall, the findings showed the potential of integrated disease management strategies involving fungicides and botanicals to mitigate the Alternaria leaf spot in marigold.