Eliminating leaf scald disease in sugarcane: efficacy of hot water and cold soak treatments

Seed cane treatments play a crucial role in managing the primary transmission of sugarcane diseases, ensuring the establishment of healthy sugarcane nurseries for commercial plantations. Leaf scald is one of the major diseases in sugarcane that is primarily transmitted via infected seed cane. The present study was done to test the effectiveness of the hot water treatment (HWT) and adoption of cold soak treatment (CST) to find the optimum combination of seed cane treatment for the production of leaf scald disease (LSD) free-seed cane for sugarcane nurseries. Twelve-months old LSD affected seed cane was treated at 24, 36, and 48 h CST treatments followed by another set of treatments at 54 °C for 50 and 120 min of HWT. A field trial was conducted to record germination, LSD symptoms, and yield in the plant crops. Latent infection of the LSD pathogen in the plants was detected by PCR with L1 and Ala4 primer pairs specific to the Xanthomonas genus. The results revealed that the CST at 36 h followed by 54 °C for 50 min HWT showed significantly higher germination and cane yield. Moreover, the disease incidence was significantly low compared to other treatment combinations and low pathogen titer in the plant crop. Any duration of only CST treatments was ineffective in significantly reducing the level of inoculum in the infected seed cane. Although CST was applied, the 120 min HWT combination resulted in poor germination that led to low cane yield. Moreover, our findings confirmed that neither HWT nor CST or its combination was effective in eliminating LSD pathogens from infected seed canes. Although the LSD pathogen was not eliminated from the infected seed cane, the combination of CST at 36 h followed by HWT at 54 °C for 50 min can be adopted as a new recommendation to reduce the primary transmission of leaf scald disease.