Control of Damping-Off Pathogens in Soilless Container Media. Christine T. Stephens, Associate Professor, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824-1312. Thomas C. Stebbins, Research Technician, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824-1312. Plant Dis. 69:494-496. Accepted for publication 6 December 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-494.

Control of damping-off of impatiens seedlings with commonly used greenhouse fungicides was variable and dependent on the growing media in which the plants were grown. Damping-off caused by Rhizoctonia solani or Pythium ultimum was readily controlled in peat, composted pine bark, and composted hardwood bark media drenched with the more effective fungicides. Control of damping-off was least effective in processed pine bark. Metalaxyl outperformed several other fungicides in controlling Pythium damping-off in this study. PCNB was slightly more effective than ethazol plus thiophanate methyl or benomyl at low rates, but all provided excellent control of Rhizoctonia damping-off. There was less Pythium and Rhizoctonia damping-off in untreated composted hardwood bark than in other media tested, and addition of fungicides to this medium did not adversely affect its suppressive characteristics.