Shoot Blight and Collar Rot of Pinus resinosa Caused by Sphaeropsis sapinea in Forest Tree Nurseries. M. A. Palmer, Research Plant Pathologist, USDA Forest Service, North Central Forest Experiment Station, St. Paul, MN 55108. T. H. Nicholls, Research Plant Pathologist, USDA Forest Service, North Central Forest Experiment Station, St. Paul, MN 55108. Plant Dis. 69:739-740. Accepted for publication 2 March 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1985. DOI: 10.1094/PD-69-739.

Symptom development and impact of Sphaeropsis sapinea (= Diplodia pinea) on red pine seedlings were studied during 1981 and 1982 at two forest tree nurseries in Wisconsin. Two distinct symptoms, shoot blight and collar rot, were associated with infection by S. sapinea. Shoot blight, characterized by stunted dead shoots and needles, was found in 1-, 2-, and 3-yr-old seedlings. This type of infection caused the most losses. The most severe losses occurred in 1981, when 34.5% of the 1-yr-old red pine seedlings were infected in one nursery. Collar rot by S. sapinea killed trees with fully elongated shoots. Losses caused by collar rot were less than 1% in 1982 at both nurseries.