The Use of Forced Heated Air to Manage Botrytis Stem Blight of Geranium Stock Plants in a Commercial Greenhouse. M. K. Hausbeck, Former Graduate Research Assistant, Research Assistant, Pennsylvania State University, University Park 16802. S. P. Pennypacker, Professor, and R. E. Stevenson, Senior Research Assistant, Pennsylvania State University, University Park 16802. Plant Dis. 80:940-943. Accepted for publication 13 May 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0940.

The impact of forced heated air continuously applied from beneath an open-bottom bench on the incidence of Botrytis stem blight and inoculum production was assessed in a commercial greenhouse planting of geranium stock plants. The forced heated air treatment significantly reduced the incidence of stem blight and sporulation on blighted stems and necrotic leaves of stock plants compared to the control. This reduced incidence of necrotic leaves with sporulating Botrytis cinerea with their concomitant decrease in fresh and dry weights at the end of the growing season for those plants exposed to forced healed air clearly shows the efficacy of this treatment. In addition, during days when grower activity was documented, B. cinerea conidial concentrations estimated using a Burkard recording spore trap were lower in the modified area than in the control area.