Soil Scientist. Presently Assistant Professor, Dept. of Plant and Soil Sciences, Univ. of Maine, Orono, ME 04469.
Graduate Assistant. Presently Assistant Professor, Dept. of Vegetative Crops, Cornell Univ., Ithaca, NY 14853.
Associate Horticulturalist. Mississippi Agr. and For. Expt. Sta., Beaumont, MS 39423.
Associate Professor and former Graduate Assistant.
Received for publication 17 May 1984. Journal series paper 188 of the Virginia Truck and Ornamentals Res. Sta. The authors acknowledge the permission of E. Mapp Dunton, Jr., for use of data generated under his direction. 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.