Received for publication 10 Dec. 1983. Scientific Article No. A-4235 and Contribution No. 7223 of the Maryland Agricultural Experiment Station, Dept. of Horticulture. We wish to thank the small farms program of the USDA-NE Region for partial support of this project. 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.