Author
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GALLIAN, JOHN - UNIV. IDAHO, TWIN FALLS |
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Wintermantel, William - Bill |
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HAMM, P - OREGON ST UNIV, HERMISTON |
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/9/2001 Publication Date: N/A Citation: N/A Interpretive Summary: Rhizomania, caused by Beet necrotic yellow vein virus (BNYVV) and vectored by the soil-borne fungus Polymyxa betae Keskin, is one of the most economically damaging diseases affecting sugar beets (Beta vulgaris L.) world wide, and has been found in most sugar beet growing areas of the United States. During harvest in October 2000, sugar beets exhibiting typical symptoms of rhizomania were found in a field near Paterson, WA. These symptoms included stunted taproots, with vascular discoloration and a proliferation of lateral rootlets. Leaves were chlorotic. Four soil samples were taken from areas of the field exhibiting symptoms. Each sample was split, then diluted with an equal amount of sterile sand. Seeds of rhizomania-susceptible sugar beet variety Beta 8422 were planted in the soil/sand mix, and were maintained under conditions conducive to virus increase and rhizomania development at both the University of Idaho-Twin Falls and the USDA-ARS, in Salinas, CA. After eight weeks standard tests (ELISA) were performed on roots of plants. Two of the four samples were positive for BNYVV in the ELISA tests at both locations, based on absorbance4 values at least three times those of healthy controls. Several additional fields have subsequently been confirmed within a 24 km area, based on symptomology and ELISA. There are approximately 3240 ha of sugar beets grown in the region, and growers have been advised as a result of this confirmation to plant resistant varieties and increase the sugar beet rotation interval with non-host crops to a minimum of four years. Technical Abstract: During harvest in October 2000, sugar beets exhibiting typical symptoms of rhizomania were found in a field near Paterson, WA. Symptomatic roots from the field were stunted, with vascular discoloration and a proliferation of lateral rootlets. Leaves were chlorotic. Four soil samples were taken from areas of the field exhibiting symptoms. Each sample was split, then diluted with an equal amount of sterile sand. Seeds of rhizomania- susceptible sugar beet variety Beta 8422 were planted in the soil/sand mix, and were maintained in a controlled environment at 24 C and 12 hr day- length at one location and in the greenhouse at another. After eight weeks ELISA was performed on roots of plants grown at each location. Triple- antibody sandwich (TAS) ELISA (Agdia, Inc., Elkhart, Indiana) was conducted at the University of Idaho, and antiserum specific for BNYVV. Two of the four samples were positive for BNYVV in the ELISA tests at both locations, based on absorbance values at least three times those of healthy controls. Several additional fields have subsequently been confirmed within a 24 km area, based on symptomology and ELISA. |