Geographic distribution and genetic diversity of three Ophiosphaerella species that cause spring dead spot of bermudagrass

The distribution of three Ophiosphaerella spp, that cause spring dead spot (SDS) of bermudagrass was studied by systematically sampling two golf cours es in Oklahoma and one in Kansas. O. herpotricha was isolated from all thre e locations and was the most abundant species. It was the only SDS pathogen found at Jenks, Oklahoma. O. korrae was isolated from Afton, Oklahoma, and Independence, Kansas, whereas O. narmari was only detected in samples from Afton. This is the first report of all three Ophiosphaerella species on be rmudagrass at the same location. Amplified fragment length polymorphism (AF LP) marker analysis was used to investigate inter- and intraspecific geneti c diversity of Ophiosphaerella isolates from North America and Australia. A majority of the O. herpotricha and O. narmari isolates from Afton were dis tinct haplotypes, suggesting that sexual recombination was occurring within the population. Conversely, the presence of multiple isolates of O. herpot richa and O. narmari with the same haplotype also indicated that asexual pr opagation was occurring. The genetic diversity among O. herpotricha isolate s from Afton was not distinctly different from that of isolates collected t hroughout the southern United States. In contrast, O. narmari isolates from Afton were distinct from those collected in Australia. The genetic diversi ty in O. korrae was markedly different than that in the other Ophiosphaerel la spp. The population at Afton was dominated by just a few haplotypes, and these were nearly identical to isolates collected from bermudagrass and Ke ntucky bluegrass throughout western, central, and northern North America. H owever, O. korrae isolates collected in the southeastern United States were only distantly similar to other North American isolates.