Received for publication July 17, 1976. Journal paper no. 6348 of the Purdue University Agricultural Experiment Station. This study was funded by Specific Cooperative Agreement No. 12-14-3001-559 between Purdue University and the U.S. Department of Agriculture.
Graduate Research Assistant and Professor of Horticulture, respectively. The authors gratefully acknowledge the contributions of Drs. H. J. Brooks, W. A. Oitto, and R. C. Blake, and Mr. W. Zook, and all other persons involved in the USDA Pear Breeding Program, and of Dr. R. E. Cooper and Ms. Rosemary Guthrie of the Numerical Analysis Branch of the Data Systems Application Division, USDA-ARS, Beltsville, Maryland, for assistance in computer analysis.
Research Plant Physiologist and Research Plant Pathologist, respectively.