Abstract

Sorghum (Sorghum vulgare) is the most important millet culti- vated in Tamil Nadu and is subject to a number of diseases like smuts and leaf spots. Amongst the leaf diseases, leaf spot caused by Cercospora sorghi Ell & Ev. and leaf blight caused by Bipolaris turcicum (Pass). Shoemaker, are of major importance and are widely prevalent in this state. A survey was conducted in the districts of Madurai, Ramanathapuram and Coimbatore in Tamil Nadu to assess the prevalence and intensity of these diseases. It was found that the leaf blight caused by Bipolaris turcicum was comparatively more prevalent in most of the places visited in these districts than the leaf spot caused by Cercospora sorghi. These leaf diseases affect both rainfed and irrigated crops and assume serious proportions during spells of wet weather resulting in loss of yield and deterioration in fodder quality. In China, Porter (1926) recorded a loss of 5% in yield due to leaf spot disease caused by Cercospora sp. The exact figures relating to loss caused by leaf diseases in sorghum in this State are not available; but considering their wide prevalence and often with high intensity the loss must be substantial. In order to minimise the heavy losses caused by these leaf diseases investigations have been undertaken for evolving effective control measures. Field experiments were conducted in order to test the relative efficacy of various fungicides in the control of the above leaf diseases and the observations made and the results obtained are presented in this paper.

Keywords: