Abstract

Angular leaf spot otherwise known as blackarm of cotton is a major disense of cotton and occurs in many cotton growing countries. In India, this disease occupies the primary importance in view of the loss it causes to the yield of cotton especially in certain States like Andhra Pradesh, Madras, Mysore and Kerala. This disease is a limiting factor in the cultivation of Sen Island cotton along the west coast areas and in places of heavy rainfall. Attempts are being made to exploit the source of resistance to this disease from a number of species and varieties of cotton. In evaluating the genetic stocks for their resistance to this disease, n suitable technique to create epiphytotics of this disease is essential as in the absence of such a technique the grading of a particular variety varies from year to year or from place to place according to seasonal variations. In the past, various methods have been described by different authors which have been briefly enumerated by Sundaram (1961). However, these techniques were found to be inadequate to create epiphytotics of the disease under field conditions. Sundaram (1961) described a technique to create the disease in an epiphytotic form under laboratory conditions based on which further studies were conducted to evolve a method to create the disease under field conditions and the results are briefly reported in this paper.

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