Efficacy of fungicides against Alternaria alternata causing alternaria blight of fennel

Fennel (Foeniculum vulgare Mill.) is a major seed spice crop, belongs to family Apiaceae (Umbelliferae). Fennel crop suffers from various diseases caused by fungi and other microorganisms. Amongst the major fungal diseases of fennel, the Alternaria blight caused by Alternaria alternata, is becoming a measure threat to the fennel cultivation. During present investigations six fungicides were evaluated against Alternaria alternata under in vitro and in vivo conditions. Among these fungicides, mancozeb + carbendazim (300 ppm) was found most effective in inhibition of mycelial growth (96.90%) and while in field, two spray of mancozeb + carbendazim (0.2%) was recorded highly effective in reducing disease intensity (71.53%) by increasing 73.07 per cent seed yield followed by mancozeb over unprotected control. The benefit cost ratio value was highest (1.95) with two sprays of mancozeb + carbendazim at 15 days interval followed by mancozeb (1.84).