Survey, molecular characterisation and in vitro management of sugarcane red rot (Colletotrichum falcatum)

Abstract

Red rot of sugarcane, caused by Colletotrichum falcatum Went (formerly Glomerella tucumanensis), is a highly destructive disease that significantly reduces sugarcane yield and quality. A field survey was conducted from August to October during 2024–2025 in five blocks of Muzaffarnagar district, Uttar Pradesh, to assess disease incidence. The highest incidence was recorded in Jansath block (11.23 %), followed by Sadar (11.13 %), while Bhagra and Shahpur each recorded 6.09 %. The lowest incidence was observed in the Purkaji block (4.71 %). Molecular identification using PCR amplification of the 18S rDNA region with universal primers (ITS1, ITS4) and specific primers (Bt-1, Bt-2) confirmed the presence of C. falcatum, producing amplicons of 570 bp and 750 bp. In vitro evaluation of biocontrol agents using the dual-culture technique revealed that Trichoderma harzianum exhibited the highest inhibition (88.89 %), followed by Trichoderma viride (80.00 %), Bacillus subtilis (72.22 %) and Pseudomonas fluorescens (66.66 %) at 9 days post-incubation. Fungicides tested at 100, 200 and 300 ppm using the food-poisoned technique showed that Carbendazim 50 % WP and Azoxystrobin 23 % SC achieved 100 % inhibition at all concentrations. Propiconazole 25 % EC and hexaconazole 5 % SC showed moderate inhibition. The findings highlight the potential use of effective biocontrol agents and fungicides for integrated management of red rot in sugarcane. These results may assist farmers and researchers in developing sustainable disease management strategies, while further field validation and long-term studies are required to confirm their effectiveness under diverse agro-climatic conditions.