Sphaeropsis sapinea on Black Spruce in Ontario. D. T. Myren, Forestry Canada, Ontario Region, Box 490, Sault Ste. Marie, Ontario, P6A 5M7, Canada. Plant Dis. 75:644. Accepted for publication 31 January 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0644A.
Samples collected from black spruce (Picea mariana (Mill.) B.S.P.) in a seed orchard at Goodie Lake (50°04' N, 92°22' W), approximately 20 km west of Sioux Lookout, Ontario, were heavily infected by Sphaeropsis sapinea (Fr.:Fr.) Dyko & Sutton in Sutton. Infection was initially found by examining small pycnidial openings on the bark surface. Peeling back the bark revealed a large number of pycnidia that had not yet broken through. Infection on the stems and branches of 20% of the trees caused death of those portions of the host distal to the infected area. The seed orchard was on a sandy site, and trees had been deprived of water to create stress and encourage cone production. The severe moisture stress probably predisposed the trees to infection by S. sapinea. Subsequent sampling of black spruce in other seed orchards in northwestern Ontario revealed three in which 4.0, 4.3, and 4.5% of trees were infected by S. sapinea. This is the first record of S. sapinea on any of the spruce species native to Ontario. Identification of S. sapinea was confirmed by J. Bissett of the Biosystematics Research Centre (BRC) in Ottawa. Voucher specimens are on deposit at BRC (DAOM 211265) and Forestry Canada, Ontario Region, (SSMF 89-5-9602).