Efficacy of Fungicides against Early Blight of Potato Caused by Alternaria Alternata (FR.) Keissler

Early blight of potato caused by Alternaria alternata (Fr.) Keissler is one of the major constraints in raising potato production in Gujarat. Five non-systemic and five systemic fungicides were screened in vitro against A. alternata. Among the non-systemic fungicides/chemicals copper oxychloride completely inhibited fungal growth even at its lower concentration (500 ppm) followed by mancozeb (97.80%) at 2500 ppm. Among the systemic fungicides, metalaxyl at 500 ppm recorded maximum growth inhibition (76.34%) followed by triadimefoil at same concentration (73.66%). In field evaluation, early blight of potato was effectively checked by three sprays of mancozeb (8.80%) and copper oxychloride (13.20%) each one was having 0.2 per cent concentration sprayed at 15 days interval recorded maximum potato tuber yield of 212.04 and 202.22 Qt/ha, respectively.