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Disease Note. First Report of Rhizomania of Sugar Beet from Texas. J. E. Duffus, Sugarbeet Production Research Unit, USDA-ARS, Salinas, CA 93905. H. Y. Liu, Sugarbeet Production Research Unit, USDA-ARS, Salinas, CA 93905. Plant Dis. 71:557. Accepted for publication 11 March 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0557B. Rhizomania, one of the most destructive diseases of sugar beet (Beta
vulgaris L.), was found in the sugar beet growing area of the Texas
Panhandle near Hereford in 1985. Rhizomania is caused by beet
necrotic yellow vein virus (BNYVV), which is vectored by the soilborne
fungus Polymyxa betae Keskin. The disease was first found in the
Western Hemisphere in California during 1983 (I). Rhizomania was
identified in Texas by the characteristic symptoms (root stunting,
proliferation of lateral rootlets, and darkened vascular rings) and the
presence of BNYVV and P. betae in the roots of affected sugar beet
plants. BNYVV reacted in ELISA tests with antiserum to Japanese,
French, and California isolates of the virus, and characteristic virus
particles were observed by electron microscopy of plant tissue dips. The
disease was found in three fields in 1985 and in two additional fields in
1986. These fields represent less than 400 ha of the approximately
15,200-ha production area. |