Int.J.Curr.Microbiol.App.Sci (2017) 6(7): 2440-2446 2440 Original Research Article https://doi.org/10.20546/ijcmas.2017.607.346 Evaluation Fungicides against Phytophthora nicotianae Causing Black Shank Disease in FCV Tobacco Both Under In vitro and In vivo K. Jayalakshmi 1* , J. Raju 1 and H. Ravindra 2 1 Department of Plant Pathology, AINRP (Tobacco), ZAHRS, University of Agricultural and Horticultural Sciences, Shivamogga, Karnataka 577204, India 2 Department of Plant Pathology, Plant Quarantine Station, DPPQS, Mangalore, Karnataka, India *Corresponding author ABSTRACT Introduction Among the commercial crops grown in India, tobacco (Nicotiana tabacum) occupies an important place not only as a valuable foreign exchange earner but also as an employment as a generating crop. Tobacco like any other crop is susceptible to several diseases in which black shank is one of the serious problem of Flue Cured Virginia tobacco in Karnataka light soil. Black shank of tobacco, caused by the hemibiotrophic oomycete Phytophthora parasitica f. sp. nicotianae (Breda de Haan) Tucker is among the most destructive and widespread of all tobacco-cultivated area (Prinsloo, 1994). The Pathogen damage the pith (the water transport system of the plant) of a plant resulted wilting, stunting, yellowing leaves and finally plant dies (Lucas, 1975). Black shank first appeared in the United States in 1915 and was first reported in North Carolina in Forsyth County in 1931. The fungus can survive in the soil for many years, even in the absence of tobacco (Shew and Lucas, 1991; Jones and Shew, 1995; Shamrao and Hundekar, 2009). The disease can be managed in many ways. For effective black shank control, growers use International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 7 (2017) pp. 2440-2446 Journal homepage: http://www.ijcmas.com Black shank, Phytophthora parasitica var. nicotianae is a major disease of tobacco results in considerable loss of the crop. An investigation was carried out to screen the different fungicides to inhibit the growth of black shank pathogen. Among eight fungicides tested at different concentrations, 0.1 per cent of Trifloxystrobin + Tebuconazole, Fenamidone + Mancozeb and Metalaxyl + Mancozeb were showed cent per cent inhibition and found effective over all the tested fungicides. Management study under field conditions was carried out during kharif 2016, revealed that the treatment with Fenamidone + Mancozeb and Cymoxanil + Mancozeb found effective in reducing the disease incidence of 19.05% and 23.02% with highest green leaf yield (10596.71 and 9920.63 kg/ha), cured leaf yield (1246.67 and 1167.13 kg/ha) and top grade equivalent (872.67 and 700.28 kg/ha) followed by Azoxystrobin and Metalaxyl Mz over untreated check. All tested fungicides were drastically reduced disease the incidence and showed a tendency to increase tobacco yield over the untreated control. Keywords Phytophthora nicotiane, Black shank, FCV tobacco, Fungicides, Management. Accepted: 26 June 2017 Available Online: 10 July 2017 Article Info