Plant Pathologist, ARS/USDA, Dept. of Plant Pathology.
Research Technician, Dept. of Botany.
Director of Research.
Received for publication on 12 Sept. 1986. Cooperative investigations of the USDA, North Carolina State Univ., and Virginia State Univ. Paper no. 10433 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, N.C.; Journal Article Series no. 150 of Virginia State Univ., Agricultural Research Station, Petersburg, Va. The use of trade names or vendors in this publication does not imply endorsement by the USDA, the North Carolina Agricultural Research Service, or Virginia State Univ. of the products named, nor criticism of similar ones not mentioned. We appreciate the assistance of Gwen Eason in data reduction and some statistical analyses, and Virginia Lesser for conducting statistical analyses and aiding in interpretation of the results. 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.