K. Abhipsa Bharadwaj, Ashirbad Panda and Rakesh Roshan Satapathy
Abstract
Alternaria leaf spot and flower blight, caused mainly by Alternaria zinniae and A. alternata, is considered one of the most damaging diseases that affects marigold (Tagetes erecta L.), widely cultivated. Yield losses can range from 50% to 60% (Dhiman and Arora, 1990; Mazumdar, 2000). This study was conducted to evaluate the in vitro efficacy of nine fungicide-based treatments against Alternaria species using the poison-food method (Tetrawal ad Ral, 2007). Eight fungicide treatments were used in the experiment: carbendazim + mancozeb (T2, 0.2%), azoxystrobin + difenoconazole (T3, 0.1%), azoxystrobin (T4, 0.1%), Difenoconazole (T5, 0.15%), carbendazim (T6, 0.1%), mancozeb (T7, 0.3%), mancozeb + thiophenate methyl (T8, 0.09 + 0.045%), and copper hydroxide (T9, 0.3%).Most treatments were highly effective, with 100% growth inhibition recorded for thiophenate methyl, carbendazim + mancozeb, carbendazim, mancozeb, and mancozeb + thiophenate methyl, as well as copper hydroxide. Difenoconazole alone showed 61.11% inhibition, and azoxystrobin + difenoconazole showed 77.77% of inhibition. However, the only application of azoxystrobin achieved only 6.66% effectiveness, suggesting a risk of resistance development. These outcomes highlight the importance of resistance management and the use of a combination of fungicides for sustainable disease management in marigold production.