Exploring potential of different fungicides for management of red rot of sugarcane under sub-tropical India

Red rot is one of the most devastating diseases of sugarcane which imposes major limitations to the profitable cultivation of this crop. The disease is primarily transmitted through sett borne inoculum in field. Although fungicides have been effectively used for disease control in several crops; there have been limited studies exploring potential of fungicides for management of sett transmitted red rot under field conditions. As such, field experiments were carried out over two crop seasons (2018–2019, 2019–2020) to evaluate six systemic fungicides and one systemic resistance inducing chemical (salicylic acid) for red rot management. The fungicides and salicylic acid (SA) were applied as sett treatment at time of planting to red rot pre-inoculated setts of variety Co 1148 and data on red rot, number of millable canes (NMC) and yield recorded in the experiment. In both years, highest red rot incidence was recorded in control plots (55–59%). Application of the fungicides and SA showed a reduction in red rot incidence over control but the extent of reduction varied considerably (10.6–39.4% reduction) across the treatments over the 2 years. Overall, among the seven fungicides evaluated, sett treatment with two fungicides (Tebuconazole + Trifloxystrobin and Thiophanate methyl) consistently resulted in > 30% reduction in red rot incidence over control in both years along with significantly higher NMC over control. Significant variations were also recorded in yield among the treatments with the above two fungicides exhibiting > 40% yield increase over control during 2018–2019 and > 27% yield increase during 2019–2020 crop season. The current study establishes that the fungicides Thiophanate methyl and Tebuconazole + Trifloxystrobin have the potential to control sett borne inoculum of red rot, which is the primary mode of red rot transmission in nature, to the tune of 30–40%. These fungicides have the potential to be exploited further either alone or in combination with other management options as part of developing effective red rot management strategy. © 2021, Indian Phytopathological Society.