Height Control of Dendrobium Orchid

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Charles W. Laughlin, Director and Dean, Cooperative Extension Service, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa, Honolulu, Hawaii 96822. An Equal Opportunity / Affirmative Action Institution providing programs and services to the people of Hawaii without regard to race, sex, age, religion, color, national origin, ancestry, disability, marital status, arrest and court record, sexual orientation, or veteran status. Objective The purpose of this experiment was to determine if flurprimidol would be effective in controlling plant height of dendrobium orchid. Cut-flower dendrobiums offer potential as flowering potted plants because of the longevity of their floral display, but most selections are too tall at blooming for ease of handling in the pot sizes normally used in the trade. Flurprimidol has been reported as a highly effective retardant on a number of flowering ornamentals (Barrett 1983). For comparison, ancymidol (Arest) and ethephon (Florel) were evaluated—ancymidol because it is an analogue of flurprimidol and ethephon because of its success as a retardant when applied as a drench (Shanks 1969, Freeborg and Daniel 1979).