Black shank disease incited by Phytophthora parasitica var. nicotianae (Breda de Haan) Tucker is a serious fungal disease in Flue Cured Virginia (FCV) Tobacco nurseries in Karnataka. The pathogen affects roots, basal portion of stem besides leaves andcauses heavy loss of seedlings under favourable conditions. (Patel & Patel, 1999). The indiscriminate use of the copper fungicides against Black shank disease in FCV tobacco has met with several disadvantages. Five drenching sprays of copper oxy-chloride (recommended practice) has resulted in toxicity to seedlings due to residual effect besides reduction of beneficial organisms in soil. Whereas, soil application of metalaxyl for five years in tobacco field crop has led to development of resistant strains of Phytophthora parasitica var. nicotianae (Shew, 1985). The use of plant based organic products against diseases management is gaining importance in view of their pollution free, low cost and long lasting effect. The first scientific report on the benefit of the plant extracts and other organic materials in disease management appeared 50 years ago, which included control of potato scab and root rot of cotton (Nandan and Narwal, 1995). Several botanicals are currently being tested and exploited for disease as well as pest control with a view to avoid the harmful effect of synthetic fungicides. A number of plant species have been recognized to posses some natural substances in their leaves, which were toxic to many plant pathogenic fungi (Singh et al, 1986). Some of the toxic substances obtained from various plant species have been reported to control a number of fungal diseases of the plants (Shetty et al., 1989; Singh and Dwivedi, 1990). The present investigation" was undertaken to test the efficacy of locally available plant extracts against the black shank which is very important disease in most of the FCV tobacco nurseries of Karnataka.
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