Identification of Epicoccum sorghinum and its Effect on Stalk Sugar Yield

Ring spot disease of sugarcane is associated with several fungal pathogens worldwide. In the Philippines, the disease is considered a minor one with limited knowledge of its pathosystem. Thus, this present study was conducted (1) to identify the fungal pathogen associated with ring spot of sugarcane through combined morphological and molecular characterization, (2) to determine the pathogenicity of the isolated fungus in detached leaf and planta trials, and (3) to evaluate its effects on the stalk sugar yield. Morphological characters and gene sequences of internal transcribed spacer (ITS-rDNA), beta-tubulin (TUB2) and actin (ACT) regions of fungal isolates VNOC62a and VNR26 showed high similarity with Epicoccum sorghinum. Both isolates were pathogenic in detached leaf, and planta trials and the same fungi were reisolated from the symptomatic leaves, thereby fulfilling Koch’s postulate. Further, E. sorghinum VNOC62a significantly reduced the stalk sugar level (Brix) at seven-day post-inoculation (dpi) while E. sorghinum VNR26 reduced sugar level at 14 dpi. This study successfully identified Epicoccum sorghinum as the cause of ring spot of sugarcane and revealed to significantly reduce stalk sugar yield, in vitro.