Changing dynamics of red rot epidemics in Sugarcane in India: twelve decades of journey and lessons learnt

Abstract

From the first batch of hybridization programme, along with Co 205, the other varieties Co 210, Co 213 and Co 214 had become commercially popular in the subtropical region after 1920s. This effort was highly successful and made a revolution in sugarcane agriculture in a short period. Hundreds of elite varieties developed at Coimbatore and other research centres in different states in the past decades were deployed for cultivation in red rot prone areas as varietal replacements that came with huge cost for the farmers and mills. The industries incurred huge losses during severe epidemics like those in Co 213 in the subtropics and CoC 671 in the tropics. On the positive side, determined efforts were made to replace the affected areas with new varieties through robust varietal development programme in India. This displays exceptional work done by the sugarcane researchers especially the breeding and pathology groups. The historical red rot epidemics of 1930s, 1940s, 1980s and present epidemics in UP and Bihar and epidemics of CoC 671 in the tropical states in 1990s follow a path of boom and bust cycle and this reiterates avoidance of monoculture of a single variety in a large command area. Each and every boom and bust cycle has left a permanent mark on aggressiveness and heightened virulence of C. falcatum hence it is advised to adopt a mosaic pattern of varieties to combat the menace. New aggressive pathotypes with greater virulence cause strong erosion of host resistance and quick failure of new varieties. In the history, we found emergence of highly sporulating light type isolates with enhanced virulence over the earlier less virulent dark types. During 1880 to 1930, the countries such as USA, Argentina, Australia, Brazil, Cuba, Indonesia, Mauritius, Puerto Rico and West Indies had witnessed severe red rot epidemics in sugarcane; however, currently they do not have serious disease threat. These countries have successfully managed the threat through proper field sanitation and quarantine, whereas, India failed in this area and continue to battle with the menace for more than a century. Henceforth serious efforts are to be taken to eradicate all the susceptible varieties in the field even though their spread is in few pockets. Such pockets serve as reservoir for the pathogen inoculum leading to varietal breakdown in the new varieties. By adopting this integrated approach the country will harness the benefits from genetic gain achieved in many elite sugarcane varieties. Also disease surveillance has to be given due importance to take appropriate measures to contain the outbreaks immediately after its first report. Hiding the information and wrong advisories blow up the disease spread to large areas. Learning from the past mistakes will make better future for the farmers in the country.