Abstract
Creeping bentgrass commonly is grown on golf courses in the United States. In the fall of 1998, symptoms of a new disease were observed on bentgrass putting greens in three states. The causal agent was determined to be an undescribed species of Ophiosphaerella based on morphological characteristics. This was supported by sequence analysis of the complete ITS region of the rDNA. A new species, Ophiosphaerella agrostis, is described based on these morphological and molecular analyses. Intraspecific genetic variation was assessed using amplified fragment length polymorphism DNA fingerprinting of 17 isolates collected from nine different locations. A 90% similarity was found among the isolates.