Received for publication September 18, 1982. Alabama Agricultural Experiment Station Journal No. 11-82292. Appreciation is expressed to Paul Ecke Poinsettias, Encinitas, Calif, and Jiffy Posts of America, West Chicago, Ill. for donating materials used in this research. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.