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Disease Detection and Losses

Relationship of Age of Plants and Resistance to a Severe Isolate of the Beet Curly Top Virus. James E. Duffus, Plant Pathologist, Agricultural Research Service, United States Department of Agriculture, U. S. Agricultural Research Station, P. O. Box 5098, Salinas, CA 93901; Irvin O. Skoyen, Agronomist, Agricultural Research Service, United States Department of Agriculture, U.S. Agricultural Research Station, P. O. Box 5098, Salinas, CA 93901. Phytopathology 67:151-154. Accepted for publication 17 September 1976. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-151.

Strains of the curly top virus capable of causing appreciable damage to resistant cultivars of sugar beet are found throughout the western United States. However, little knowledge of the extent of the damage induced by these isolates was known. Field trials on sugar beets have indicated that current strains of the curly top virus caused serious losses, even when inoculated as late as 10 wk after seeding or after more than 40% of the growing period had elapsed. Both root yield and sucrose content were significantly reduced. Disease resistance appears to be associated with differences in incubation period rather than differences in the abilities of resistant cultivars to recover from the effects of virus infection.