Biological effectiveness of fungicides Rango, Tacora, Velficur and Opus for control of Karnal Bunt

Commercial fungicides Rango, Tacora, Velficur, and Opus were evaluated in the field, to determine their biological effectiveness to control karnal bunt (Tilletia indica) of wheat. A completely randomized design was used with four replications. Twenty heads of cultivar Tacupeto F2001 were inoculated during the boot stage with an allantoid sporidial suspension (10,000/mL). Commercial rates indicated in the containers of each product were followed. The first application was carried out ten days after inoculation (Zadoks stages 56-58), and the second one ten days later. Inoculated spikes were threshed by hand and the healthy and infected kernels were counted to determine the percentage of infection. Two hundred grains per treatment and per replication were weighed. The biological effectiveness of the products evaluated were Opus 91.6, Velficur 83.2, Tacora 80.2, and Rango 70.3%. The untreated inoculated check had a mean of 18.6% infection. There were no statistical differences for the products evaluated for level of infection after arcsin transformation (Tukey, p = 0.05) and the coefficient of variation was 16.2%. The average weight of 200 grains per treatment was 10.6, 10.5, 10.6, and 10.7 g, respectively, and 10.7 g for the untreated inoculated check. No phytotoxic effects of treatments applied to the wheat plant were observed.