Received for publication 8 June 1984. The investigation reported in this paper (84-10-103) is in connection with a project of the Kentucky Agr. Expt. Sta. and is published with approval of the Director. This project was supported in part by a grant from the Kentucky Dept. of Agr. 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.