Use of Colletotrichum graminicola KA001 to control barnyard grass

Isolates of Colletotrichum graminicola were obtained from barnyard grass sh owing anthracnose symptoms and the fungus was evaluated as a potential bioc ontrol agent. C. graminicola KA001 was highly pathogenic to two varieties o f barnyard grass in a wide range of growth stages, with the most damage at the three- to four-leaf stages. Disease severity of barnyard grass increase d with the increase of the inoculum density from 1 x 10(4) to 1 x 10(5) con idia/ml, but inoculum density above 1 x 10(6) conidia/ml did not increase d isease severity. A total of 13 rice cultivars tested showed no disease symp toms when inoculated with this fungus. Appressoria were formed on both barn yard grass and rice leaves, but infection hyphae were only found in the cel ls of barnyard grass. The fungus grew and sporulated in a wide range of tem perature regimes, with optimal temperature at 27 to 30 degrees C. These dat a suggest that C. graminicola KA001 has potential as a mycoherbicide to con trol barnyard grass with a safe selectivity in rice fields.