First Report of Ploioderma lethale on Pinus mugo. G. W. Hudler, Department of Plant Pathology, Cornell University, Ithaca, NY 14853. S. E. Jensen, Department of Plant Pathology, Cornell University, Ithaca, NY 14853. Plant Dis. 76:101. Accepted for publication 10 September 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0101A.
In the town of Andes in Delaware County, New York, in July 1990, two small (0.05-1.0 m tall) mugo pines (Pinus mugo Turra) growing in a residential landscape 20 m from a stand of Austrian pine (P. nigra Arnold) infected with Ploioderma lethale (Dearn.) Darker were also found to be infected by the pathogen. Identification of the fungus was based on comparisons of mature ascocarps with a description of the fungus (CMI Descriptions of Pathogenic Fungi and Bacteria No. 570) and with specimens of the pathogen at the Cornell Plant Pathology Herbarium (CUP No. 43746,55644). Ascocarps were elongate (up to 1,700 µm long), black, and subepidermal at first and occurred on both abaxial and adaxial surfaces of current year's needles. Unitunicate asci within averaged 110 I'm long X 15 I'm wide (22 measurements) and each contained eight ascospores. Ascospores averaged 23 I'm long X 4 µm wide (46 measurements) and each was surrounded with a gelatinous sheath. P. lethale is reported only from North America and, prior to this report, only on P. nigra and native species of Pinus. A voucher specimen is on file at the Cornell University Plant Pathology Herbarium as CUP No. 61974.