Beta maritima as a Source of Powdery Mildew Resistance in Sugar Beet. E. D. Whitney, Research Plant Pathologist, U.S. Department of Agriculture, Agricultural Research Service, Salinas, CA 93905. . Plant Dis. 73:487-489. Accepted for publication 1 December 1988. 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, 1989. DOI: 10.1094/PD-73-0487.

Fifty-five accessions of Beta maritima were tested in the greenhouse for resistance to Erysiphe polygoni from sugar beet (B. vulgaris). Reactions varied from highly susceptible to visually free of mildew. Field tests of selected accessions and accessions resistant to rhizomania showed high levels of resistance to powdery mildew. Crosses between plants that were free of mildew in greenhouse tests produced some families that also were mildew-free. Outcrosses to sugar beet were fruitful and also showed high resistance to mildew. High levels of resistance in B. maritima were found in accessions from Denmark, France, Greece, and The Netherlands. These accessions should provide new sources of resistance to powdery mildew in sugar beet.