Received for publication 3 Apr. 1984. Mention of a growth regulator in this paper does not constitute a recommendation for use by the USDA nor does it imply registration under FIFRA. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the USDA and does not imply its approval to the exclusion of other products that may also be suitable. 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.