Abstract

Tobacco is an important money crop in South India especially in the Madras and Andra States. It is extensively cultivated in Nellore, Guntur, Krishna, West and East Godavari districts of Andhra State and occupies an area of more than one hundred thousand acres. Extensive areas of nurseries under the Virginian variety of tobacco are raised in the sandy belt from Bapatla to Kotha- patnam (Coastal tract of the Guntur district) and in the black soil areas of Repalle, Guntur, Sattanapalle and Narasaraopet in the Guntur district to meet the requirements of seedlings for planting the above area. The chief limiting factor in the raising of nurseries was found to be the "damping off" disease of seedlings. This disease has been reported from most of the tobacco growing countries of the world. Several species of Pythium and Rhizoctonia solani have been shown to be associated with the "damping off" of seedlings. P. aphanidermatum (Eds.) Fitz. is the causal agent in India (Thomas 1943) and also in South Africa (Wager 1931, 1940), China (Yu 1934, Yu et al 1945), Gold Coast (Bunting and Dade 1924; Simond 1939). P. aphanidermatum has been found to be. widely prevalent in all types of soils in the tobacco growing areas in the Madras State (undivided). Diseased seedlings collected from nurseries raised in sandy as well as black soil tracts in the important nursery areas showed the presence of P. aphanidermatum.

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