Seedling Blight of Longleaf Pine Caused by a Binucleate Rhizoctonia solani-like Fungus. J. T. English, Former Biologist, Florida Division of Forestry, FDACS. R. C. Ploetz, Visiting Assistant in Plant Pathology, NFREC, Route 3, Box 4370, Quincy, FL 32351, and E. L. Barnard, Forest Pathologist, Florida Divisions of Forestry and Plant Industry, FDACS, P.O. Box 1269, Gainesville 32602. Plant Dis. 70:148-150. Accepted for publication 5 August 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-148.

A pathogen that causes blight of longleaf pine seedlings in nurseries in Florida that was originally identified as Rhizoctonia solani is described in this paper as a binucleate R. solani-like fungus. The fungus belongs to anastomosis group 3 of Ceratobasidium spp. (CAG 3) on the basis of anastomosis trials with isolates representing six anastomosis groups. In greenhouse trials, longleaf pine seedlings grown in autoclaved soil infested with an isolate of the fungus showed symptoms of both preemergence and postemergence damping-off. Over a 2-yr period in one commercial forest tree nursery, losses associated with blight caused by this organism varied with seed lot age and ranged from 0.4 to 18.9%.