YELLOW LEAF DISEASE OF SUGARCANE: OCCURRENCE AND IMPACT OF INFECTED SETTS ON DISEASE SEVERITY AND YIELD

摘要

Yellow leaf disease (YLD) caused by sugarcane yellow leaf virus (SCYLV) is a recently reported disease of sugarcane. Survey for the occurrence of the disease in the field revealed moderate to severe YLD on Co 86032, CoV 92102, CoV 94101 and other varieties under cultivation. Studies conducted on the impact of YLD infection showed reduced germination due to planting of infected setts in most of the tested varieties. The reduction in germination ranged from 3.56 to 71.57 per cent in the trials. Further it was found that SCYLV infection enhances disease expression, adversely affecting sugarcane growth and juice quality with a set of sugarcane varieties. Severe infection of YLD in certain cultivars resulted in reduced cane girth and juice quality. In different trials, the YLD infection has significantly reduced the number of canes in the field in most of the varieties tested. Planting of setts from YLD infected canes showed disease expression up to 100 per cent in varieties such as Co 658, Co 6304, Co 86250, CoC 86062 and CoJ 64. In other varieties the disease expression varied from 60.87 to 93.75 per cent. Analysis of juice from infected and healthy cane stalks showed that YLD infection reduced the sucrose levels in five of the nine varieties in the first trial and eight of the seventeen varieties in the second trial. However, rest of the varieties recorded higher sucrose levels in disease infected cane stalk.