Latent Infection of Austrian and Scots Pine Tissues by Sphaeropsis sapinea.

This study documents latent infection of Austrian and Scots pine tissues by Sphaeropsis sapinea, the causal agent of Sphaeropsis tip blight disease. Symptomless shoots from diseased or apparently healthy Austrian and Scots pine trees were cultured and analyzed for the presence of S. sapinea. Nearly half of the sampled Austrian and Scots pine trees that appeared to be completely healthy had detectable latent S. sapinea infections. More than half of the symptomless shoots on visibly diseased Austrian and Scots pine trees were also latently infected with S. sapinea. S. sapinea was isolated from symptomless shoot stems, needles, buds, immature cones, and male flowers. In symptomless infected shoots, the fungus was primarily associated with the bark and phloem tissues. Six isolates of S. sapinea from symptomless Austrian and Scots pine shoot tissues were pathogenic on Austrian pine seedlings in the greenhouse. The presence of S. sapinea in symptomless tissues of tip blight-diseased trees has important implications for disease management.