Influence of carbon, nitrogen, temperature and pH on the growth of Cercospora nicotianae causes frog eye leaf spot disease of tobacco

The paper gives an account of the variations in nutritional and physiological characteristics found in different isolate of Cercospora nicotianae causing frog eye leaf spot disease of tobacco, in India. The pathogen under study varied in their ability to grow in different temperature and pH levels and to utilize different carbon and nitrogen sources. Fructose was found to be the best source of carbon for the growth and sporulation of this pathogen. Among the nitrogen sources tested, Ammonium nitrate supported the maximum growth of the fungus followed by potassium nitrate.The optimum temperature range is between 20 to 30[degrees]C levels are identified as ideal for growth and sporulation. The least dry mycelial weight was found at below 20[degrees]C and above 40[degrees]C. The pathogen grew well at pH of 5 to pH 6 favoured maximum growth and development of the fungus. Whereas, least growth was observed at pH 3. Keywords: Tobacco, frog eye leaf spot, Cercospora nicotianae, Nutritional, physiological studies.