Received for publication 19 Aug. 1985. Journal Paper no. 10,459, Purdue Univ. Agr. Expt. Sta., West Lafayette, IN 47907. This research was supported in part by the U.S. Dept. of Agriculture (Cooperative Agreement Research Grant No. 585114-4-6001). Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty by Purdue Univ. or the USDA, North Carolina Agricultural Research Service, and does not imply approval of it to the exclusion of other products or vendors 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.
Former Research Associate. Present address: Dept. of Horticulture, Clemson Univ., Pee Dee Research and Education Center, Florence, SC 29503.