Wound-Healing Process in Geranium Cuttings in Relationship to Basal Stem Rot Caused by Pythium ultimum. Molly Niedbalski Cline, Postdoctoral Extension Associate, Department of Plant Pathology, University of Illinois at Urbana-Champaign, Urbana 61801. Dan Neely, Plant Pathologist, Section of Botany and Plant Pathology, Illinois Natural History Survey, Champaign, IL 61820. Plant Dis. 67:636-638. Accepted for publication 19 November 1982. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-636.

Cuttings of Pelargonium × hortorum Bailey cultivars Blaze, Yours Truly, and Salmon Irene were inoculated with an isolate of Pythium ultimum at various stages in the wound-healing process. Disease severity and incidence decreased as the period of time between wounding and inoculation increased, particularly with Yours Truly. Extensive basal stem rot occurred on all freshly broken cuttings but was restricted on cuttings that had been healing 1 day before inoculation. Basal stem rot rarely occurred on cuttings that had been healing for 2 days or longer before inoculation. Disease severity decreased in all three cultivars when Rootone F or Hormodin No. 1 was used before inoculation. Severity ratings generally increased as the time of air-drying before inoculation increased.