Molecular Characterization and Pathogenicity of Colletotrichum falcatum Causing Red Rot on Sugarcane in Southern Florida

Red rot disease reduces sugarcane yield and impacts the sugar quality, posing an important threat to the sugarcane industry in Florida. Although <i>Colletotrichum falcatum</i>, the causal agent of red rot in Florida, was first reported in 1984 based on morphology, molecular and pathological data have remained limited, highlighting the critical need for comprehensive characterization. Thirteen isolates were obtained from three local sugarcane varieties in Belle Glade, Florida. Phylogenetic analyses of five genetic markers (ITS, <i>ACT</i>, <i>TUB2</i>, <i>GAPDH</i>, and <i>CHS-1</i>) confirmed all the strains as <i>C. falcatum</i>. In addition, the study documented the disease progression at the cellular level and assessed the pathogenicity of representative strains using the leaf sheath and whole-seedling inoculation methods. The varieties CP96-1252 and CP89-2143 showed greater host resistance. These findings represent the first report of <i>C. falcatum</i> causing red rot in southern Florida, offer valuable insights for/into red rot management, and provide a basis for future breeding programs to enhance sugarcane resistance to red rot disease.