Red Thread and Pink Patch Diseases of Turfgrasses. Jonathan D. Kaplan, Former Graduate Research Assistant, Department of Plant Pathology/Entomology, University of Rhode Island, Kingston 02881. Noel Jackson, Professor, Department of Plant Pathology/Entomology, University of Rhode Island, Kingston 02881. Plant Dis. 67:159-162. Accepted for publication 1 July 1982. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-159.

Two groups of basidiomycetous fungi with pink mycelia were found to be associated with a turf ailment commonly referred to as red thread, pink patch, or Corticium disease. This disease complex is caused by a group of different fungi but was previously attributed exclusively to the pathogenic activities of Corticium fuciforme. The predominant group was composed of isolates of Laetisaria fuciformis forming red thread, needle, or antlerlike stromata on grass blades and had hyphae without clamp connections. A second heterogeneous group contained a number of fungi, including Athelia fuciformis, that had hyphae with clamp connections. Physiological and pathological studies on selected isolates from the two groups demonstrated differences in growth rate, temperature parameters, method of ingress, and response to certain fungicides. It is proposed that the name “red thread” disease be restricted to describe symptoms and signs of the turf disease caused by the fungus L. fuciformis. Turf exhibiting similar disease symptoms, but lacking needlelike red stromata should be referred to as “pink patch” caused by A. fuciformis and perhaps several other basidiomycetes with pink, clamped mycelium.