2,3-Dihydro-5-6-diphenyl-l,4-oxanthin (UNI-P293), was used to determine its effectiveness as a disbudding agent of Chrysanthemum morifolium cv. May Shoesmith. Concentrations of 0.5, 0.75 and 1.0% were applied on the 18th, 21st and 24th short day (SD). The optimum concentration on the 18th SD was 0.5% and 1.00% on the 21st SD. There was no difference among concentration levels on the 24th SD. Flower size and date of anthesis were not adversely affected when manual disbudding was used as a supplement to chemical treatment, but smaller flowers and delayed anthesis usually occurred when only the chemical was used for disbudding. All treated plants were shorter than untreated plants.
Received for publication October 14, 1975. Paper No. 4803 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh. From a dissertation presented by the senior author in partial fulfillment of the requirements for the Master of Science degree.
Present address: Agricultural Bank of Greece, Iraclion, Crete, Greece. Chrysanthemum cuttings were supplied by Yoder Brothers, Inc., Barberton, OH and UNI-P293 by Uniroyal Chemical, Inc., Bethany, CT. The authors are grateful to the Agricultural Bank of Greece whose financial support of the senior author made his graduate studies possible. Use of trade names does not imply endorsement by the North Carolina Agricultural Experiment Station of the products named, nor criticism of similar ones not mentioned.