Abstract
Red rot is one of the most important and widely distributed diseases of sugarcane that causes substantial loss to the sugar industry (Hughes, 1953). Rafay and Padmanabhan (1941) reported three variants of the causal fungus differing from each other in their morphological and physiological characters. Although some studies on nutritional requirements of C. falcatum have been carried out in some foreign countiies (Ahmed, 1973 and (Mouse, 1975) but such information on local strain of C. fatcatum was lacking.
Diseased stems showing red rot symptoms were collected and isolations from the diseased material were made by applying Lanai isolation techniques. For physiological studies the fungus was grown on different culture media at cl fbrant temperatures, pH, radiation doses and light conditions. All the Lab. experiments were run in 90 ram petri plates in quardruplicate. Except otherwise mentioned, the petri plates were incubated at 28°C. Linear colony diameter was measured after eight days of incubation. Spore density was estimated with the help of haemocytometer (Ahmed, 1973). The fungus grew well on all the culture media. However, maximum growth and sporulation was obtained on modified Richard's agar (Table 1). Our local isolate bad better growth and sporulation on modified Richard's agar. This increase in growth and sporulation may be attributed to the addition of cane juice which might have stimulatory effect on its growth and sporulation. The fungus did not grow at temperature below 10°C and above 40°. However, it was maximum at 28°C (Table 2). The findings are in conformity with Ahmed and Divinagracia (1974).
Maximum growth and sporulation was obtained at pH 5.5 (Table 3) as
* Pakistan Agricultural Research Council, Islamabad. 118
