Management of leaf spot (Alternaria polianthi) of tuberose through fungicides

Six fungicides viz., mancozeb 75 WP @ 0.2%, chlorothalonil 75% WP @ 0.2%, tricyclazole 75% WP @ 0.1%, iprodione 25% + carbendazim 25% WP @ 0.1%, difenconazole 25% EC @ 0.1%, azoxystrobin 23 SC @ 0.1% were evaluated for managing leaf spot (Alternaria polianthi) of tuberose (Polianthes tuberosa L.) cv. Single Petal with during kharif, 20102013. Four sprays with azoxystrobin (0.1%) at 15 days interval, starting on disease appearance proved to be the most effective and resulted in the lowest disease incidence (10.98 PDI) compared to control (34.39 PDI). This treatment also gave a fairly good benefit: cost (B: C) ratio of 6.87. The economic analysis, however, revealed the effectiveness of a combo fungicide, iprodion (25%) + carbendazim (25%), followed by difenconazole when they were applied at 0.1% concentration. These treatments recorded highest B:C ratio of 7.11 and 6.90 with 69.98% and 71.47% disease reduction, respectively.