Assistant Professor, Department of Crop and Soil Sciences, Michigan State University, East Lansing 48824-1325
Associate Professor, Department of Horticulture and Landscape Architecture
Professor, Department of Plant and Soil Sciences
Associate Professor, Department of Statistics, Oklahoma State University, Stillwater 74078-6027
Professor, Department of Plant Pathology, Kansas State University, Manhattan 66506-5506
Field and greenhouse studies were conducted to evaluate the resistance of seed- and vegetatively propagated bermudagrass entries (Cynodon spp.) to spring dead spot caused by Ophiosphaerella herpotricha. In Kansas greenhouse studies, O. herpotricha caused root discoloration and root weight reductions in all entries tested. However, in Kansas field plots, root weight reductions were not different among entries and were not correlated with disease severity ratings. In an inoculated field study in Oklahoma, diseased areas ranged from 47 cm2 for the entry Jackpot to 262 cm2 for Poco Verde in 1995, and from 121 to 1,810 cm2 for the entries Guymon and Common in 1996. African bermudagrass (Cynodon transvaalensis) exhibited the greatest number of live shoots per diseased area in both years, due in part to its greater shoot density, but also indicating greater potential to recover from the disease. African bermudagrass, Guymon, Sundevil, Midlawn, Midfield, Ft. Reno, Mirage, and several experimental seed-propagated entries were most resistant to spring dead spot, having the lowest diseased area and greatest number of live shoots within diseased areas. In Oklahoma, severity of spring dead spot among bermudagrass entries was correlated with feeeze injury that occurred during the first winter after planting.