Infected stalks have a dull color and show large red blotches on the surface. A longitudinal section of the stalk shows red rotten tissue in the otherwise white pith. In resistant plants, the red, diseased areas are often confined to the internodes. As the disease progresses, cavities may form within the pith and bundles of hardened fibers are also visible. Leaves wilt and shrivel. Plants start to emit a foul odor and stalks are easily broken under adverse weather conditions. On leaves, small red oval or elongated lesions develop on the midrib, sometimes along its full length. Sheaths may have reddish patches and small dark spots develop only occasionally on leaf blades.
Symptoms are caused by a fungus called Glomerella tucumanensis, which can survive only short periods of time (months) in the soil. Although it is not a true soil-borne pathogen, spores washed into the soil from crop debris may produce infection in recently planted seeds or seedlings. After that, the disease spreads via spores produced in the midrib or stalks of infected plants and transported via wind, rain, heavy dew, and irrigation water. Cool, wet weather, high soil moisture and monocultures favor the disease. Drought also increases the susceptibility of the plant. Besides sugarcane, the fungus can also infect minor hosts such as maize and sorghum.
Hot water bath (for example 50°C for 2 hours) can be used to kill the pathogen on seeds and control the incidence of red rot. Biological control agents can also be used to treat seeds. These include species of fungi of the genera Chaetomium and Trichoderma and some species of the bacteria Pseudomonas. Foliar sprays based on these solutions are also effective in reducing the spread of the disease.
Always consider an integrated approach with preventive measures and biological treatments if available. Treat seeds with hot water mixed with a fungicide at 50-54°C for 2 hours to kill the pathogen (thiram for example). Chemical treatments in the field are not effective and should not be recommended.