Changing scenario of sugarcane diseases since the introduction of hybrid cane varieties: Path travelled for a century

Abstract

More than 50 diseases were recorded in sugarcane in sugarcane crop during different occasions. However, only a few diseases such as red rot, wilt, smut, yellow leaf disease (YLD), grassy shoot disease (GSD), leaf scald disease (LSD), ratoon stunting disease (RSD), rust and mosaic threatened sugarcane cultivation during different periods with varying intensities. Among these, researchers focused only on red rot on most of the occasions. Investigation on frequent breakdown of disease resistance in cane varieties to red rot established emergence of new pathotypes. The new pathotypes were found to be more virulent and the variant populations gradually adapted to the varieties in the field which resulted in the buildup of red rot in the varieties hitherto resistant; eventually, the pathogen succeeded by causing a ‘varietal breakdown’. A set of host differentials were identified to establish pathogenic variation in designated pathotypes for different zones across the country. The designated pathotypes were recommended for disease screening for the respective zones. Recently studies were conducted to establish molecular variations in C. falcatum pathotypes/ isolates. However, the genetic variations could not be related to pathogenic variations which are observed under field conditions. If we look back on the 100 years of research in sugarcane pathology, concerted efforts were made to identify resistance in germplasm and varieties to important diseases and to develop appropriate screening methodologies. This has benefited sustainable sugarcane cultivation in the country. Disease outbreaks were investigated in detail and new diseases were tackled in time. The scientific community has been benefited by the new understanding of host resistance, pathogen variation and diagnostics. The sugar industry is benefited from the virus-indexing service of the Institute to produce healthy planting material and sustain cane yield potential in commercial varieties