Sugarcane smut (Ustilago scitaminea Sydow) in Tanzania, its geographical distribution and effect on sugar cane growth and yield

A survey on sugarcane smut in Tanzania revealed that sugarcane smut Ustilago scitaminea Sydow was common in all the four major sugarcane growing areas of mainland Tanzania namely Kilombero, Mtibwa, Kagera and Tanganyika Planting Company (T.P.C.). The presence of sugarcane smut in all the sugarcane estates appeared to be associated with the susceptibility of sugarcane varieties being grown, environmental factors, lack of any adequate control measure, and agricultural operations which favour the distribution of the pathogen throughout the sugarcane estates. Among the major sugarcane varieties grown, N:CO 310 was found to be the most susceptible followed by CO421, CO 617, N:CO 376 and CO 775 respectively. At Kilombero, investigations on the effect of sugarcane smut on seven sugarcane varieties namely N:CO 376, N:CO 339, N:CO 334, D141/46, IAC 55/26, CB 3839 and EA 6906; revealed that the disease reduces the rate of growth, size, weight and quality of the infected cane plants. All the seven varieties of sugarcane were of varying susceptibility to sugarcane smut with variety IAC 55/26 being the least susceptible; varieties N:CO 376, N:CO 334, D141/46 and CB 3839 being intermediate; and varieties N;CO 339 and EA 6906 being the most susceptible. The disease was estimated to be causing a loss of about T.Sh.10 million to the sugar industry in Tanzania in each growing season. Therefore, it is suggested that highly susceptible varieties like N:CO 310 be eliminated from commercial production. At Kilombero, sugarcane varieties IAC 55/26, n:co 376, N:CO 334, d141/46 and CB 3839 could be grown, whereas varieties N:CO 339 and EA 6906 should be dropped from commercial production. In addition application of prophylactic control measures are suggested and efforts should be made to screen sugarcane varieties for smut resistance at the existing and proposed sugarcane estates in the country.