VIEW ARTICLE

Reaction of Resistant and Susceptible Sugar Beet Cultivars to Beet Yellows and Beet Western Yellows Viruses. F. J. Hills, Extension Agronomist, Department of Agronomy and Range Science, University of California, Davis, California 95616; R. J. Shepherd(2), and R. J. Wakeman(3). (2)(3)Professor of Plant Pathology, and Staff Research Associate, Department of Plant Pathology, University of California, Davis, California 95616. Phytopathology 63:621-624. Accepted for publication 4 December 1972. DOI: 10.1094/Phyto-63-621.

Sugar beet hybrids, ‘US H9B’ (resistant) and ‘US H7A’ (susceptible), and an open-pollinated breeding line, ‘C13’ selected for resistance to beet yellows and beet western yellows viruses and used as a pollen parent for US H9B, were tested for resistance to virus transmission by inoculation with few to many apterous green peach aphids. Increasing numbers of apterae increased virus infection to a similar degree with the three cultivars, hence resistance to aphid transmission was not demonstrated. Cultivar C13 exhibited internal plant resistance to both viruses as it showed relatively less reduction in root yield with increasing levels of disease than did the other cultivars. US H9B produced superior root yields at all levels of infection but relatively little of its superior performance appeared to be due to virus resistance. The selection procedure for the development of C13 apparently also resulted in the selection of heritable characteristics other than yellows resistance which contribute to the superior performance of its hybrids.