Needle Cast of European Larch Caused by Mycosphaerella laricina in Wisconsin and Iowa. R. F. Patton, Professor, Department of Plant Pathology, University of Wisconsin, Madison 53706. R. N. Spear, Specialist, Department of Plant Pathology, University of Wisconsin, Madison 53706. Plant Dis. 67:1149-1153. Accepted for publication 3 June 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-1149.

A disease that results in premature defoliation has appeared recently on European larch (Larix decidua) in plantations in Wisconsin, Iowa, and one location in Michigan. The causal fungus is Mycosphaerella laricina, heretofore known only on larch in Europe. Symptoms are described, the life cycle is reviewed, and the morphology of the fungus is discussed, especially in comparison with species on larch from Japan and Europe.