Combined Resistance in Sugar Beet to Rhizoctonia solani, Phoma betae, and Botrytis cinerea. W. M. Bugbee, Research Plant Pathologist, U.S. Department of Agriculture, Agricultural Research Service, Northern Crop Science Laboratory, P.O. 5677, Fargo, ND 58105-5677. L. G. Campbell, Research Geneticist, U.S. Department of Agriculture, Agricultural Research Service, Northern Crop Science Laboratory, P.O. 5677, Fargo, ND 58105-5677. Plant Dis. 74:353-355. Accepted for publication 29 November 1989. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1990. DOI: 10.1094/PD-74-0353.

Germ plasms FC 701/4 and FC 712 of sugar beet with resistance to crown and root rot caused by Rhizoctonia solani were developed at Fort Collins, Colorado, and germ plasms with resistance to storage rot caused by Phoma betae and Botrytis cinerea were developed at Fargo, North Dakota. In three greenhouse experiments and a field test, germ plasms F1002 and F1004, selected for resistance to P. betae and B. cinerea, also possessed a moderate level of resistance to R. solani. F1002 was selected originally from FC 701/4, an early root rot-resistant release. F1004 was selected originally from a USSR germ plasm that had been developed for resistance to storage rot caused by B. cinerea. In a storage rot evaluation experiment, germ plasm FC 712 was as resistant to P. betae and B. cinerea as were germ plasms developed specifically for resistance to storage rot. Hybrid cultivars ACH 139, with resistance to R. solani, and ACH 146, with resistance to Aphanomyces cochlioides, were moderately resistant to P. betae and B. cinerea and should store better than root rot-susceptible cultivars.

Keyword(s): multiple disease resistance.