Damping-Off, Root Rot, and Lower Stem Rot of Seed-Propagated Geraniums Caused by Pythium ultimum. M. K. Hausbeck, Former Graduate Research Assistant, Department of Horticulture, Michigan State University, East Lansing 48824-1312. C. T. Stephens, and R. D. Heins. Associate Professor, Department of Botany and Plant Pathology, and Professor, Department of Horticulture, Michigan State University, East Lansing 48824-1312. Plant Dis. 73:625-627. Accepted for publication 15 February 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0625.

Symptoms caused by Pythium ultimum on seed-propagated geraniums (Pelargonium × hortorum) are described and include damping-off, root rot, and lower stem rot. Geranium seedlings were transplanted into a soilless root medium artificially infested with low, medium, and high levels of inoculum of P. ultimum. Plant stunting caused by root rot and plant death caused by damping-off and lower stem rot were greatest when seedlings were grown in the highly infested medium.