Sugarcane wilt: Simulation of pathogenicity through different methods and environments

Abstract

Sugarcane wilt caused by Fusarium sacchari is an important stalk disease affecting sugarcane productivity in India and other Asian countries. Unlike other fungal diseases of sugarcane, efforts to artificially inoculate the disease met with limited success. Hence detailed studies were conducted to induce wilt under field conditions. Among the different methods, plug method of inoculation with spore suspension was found to be effective in inducing the disease in the stalks by artificial inoculation. In disease endemic regions of Gujarat and Haryana states the disease was induced after plug method of inoculation. However under non-endemic region like Coimbatore, disease reproduction required imposition of abiotic stresses like drought and water logging along with pathogen inoculation. In addition to pathogen inoculation in the standing canes, soil inoculation of the pathogen at the time of planting found to impede sett germination and settlings (Cane setts with roots and shoots) mortality. Inoculation of wilt-infected soil to the root zone also induced typical wilt in the susceptible varieties such as Co 6806, Co 85002, Co 62198, Co 86032 etc. Pathogenicity of F. sacchari in different inoculation methods was confirmed through re-isolation of the fungus and molecular analyses. The study concludes that artificial simulation of wilt in sugarcane is cumbersome in disease non-endemic regions as compared to the endemic regions. In addition, selection of right pathogenic isolates holds a key in simulation of the disease.