Efficacy of fungicides against Botrytis gladiolorum of gladiolus

Gladiolus blight caused by Botrytis gladiolorum is a serious threat to its successful cultivation. Eight fungicides, both systemic and non-systemic, were evaluated against the pathogen under laboratory conditions. All the test fungicides, except carbendazim and benomyl, showed good efficacy. Efficacy of three commercially available brands of mancozeb, viz. Dithane M-45, Indofil M-45 and Zebtane M-45, was also tested against the disease, but differences were non-significant. Out of the five fungicides tested under field conditions, three fungicides, namely mancozeb (Dithane M-45, 0.2%), chlorothalonil (Kavach, 0.2%) and iprodione (Rovral, 0.2%) provided very good control of the disease. These fungicides reduced foliar infection and enhanced cormel yield significantly over the control. The cost: benefit ratio was the highest with mancozeb followed by chlorothalonil. Studies on persistence of two fungicides, mancozeb and chlorothalonil, showed that mancozeb (Dithane M-45) provided protective cover for 10 days, whereas chlorothalonil (Kavach) for 15 days, indicating that the spray interval could be reduced in case of the latter fungicide.