STATUS OF LEAF FLECK CAUSED BY SUGARCANE BACILLIFORM VIRUS INCIDENCE AND SEVERITY IN DIFFERENT SUGARCANE GROWING AREAS OF KERALA AND TAMIL NADU

Abstract

Sugarcane bacilliform virus (SCBV), causing leaf fleck in sugarcane (Saccharum spp), is a major threat affecting exchange of germplasm globally. Surveys conducted in four major sugarcane growing districts of Kerala and two in Tamil Nadu during 2018-2019 revealed that the disease incidences ranged between 12 and 51% in Kerala and 28 and 56 % in Tamil Nadu. Symptoms associated with the disease include mild to severe mottling of the leaves, which were more prominent on leaf positions four to six. In Kerala, ratoon crop of the cv. Madhuri in Pathanamthitta district recorded the highest incidence (51%) and severity (36%) of leaf fleck. Least incidence (12%) and severity (10%) were recorded in Idukki district in the cv. Co 86032. Among the surveyed locations in Tamil Nadu, plant crop of cv. CoV 09356 in Villupuram district recorded the maximum percent of disease incidence (56%) and severity (50.41%) followed by Radhapuram with an incidence of 55% and severity of 43.75%. Least incidence and severity were recorded in plant crop of cv. Co 86032 at Kuchipalayam (28%). In comparison to Kerala, Tamil Nadu recorded higher incidences and severities of leaf fleck. PCR assays using primers specific to Badna viruses, confirmed the presence of the virus in collected samples. Detailed surveys conducted for leaf fleck for the first time under field conditions indicated severe occurrence of the disease in the states of Kerala and Tamil Nadu.