VIEW ARTICLE

Techniques

A Simple Method for Field and Greenhouse Inoculation of Polymyxa betae and Beet Necrotic Yellow Vein Virus. R. M. Harveson, Research associate, Department of Plant Pathology, The Texas A & M University System, Texas Agricultural Experiment Station, Bushland 79012; C. M. Rush, Professor, Department of Plant Pathology, The Texas A & M University System, Texas Agricultural Experiment Station, Bushland 79012. Phytopathology 83:1216-1219. Accepted for publication 4 August 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/Phyto-83-1216.

A method of inoculating sugar beet with viruliferous Polymyxa betae for use in field and greenhouse studies was evaluated for two years (1991–1992). Seeds of sugar beet cultivar HH39 were coated with powdered sugar beet roots containing beet necrotic yellow vein virus (BNYVV)-infested P. betae cystosori. Two percent methyl cellulose was used as the carrier at rates of 1:20:20 and 1:10:10 (w/v/w) inoculum/methyl cellulose/seed. Seeds were planted in field plots and maintained by conventional agronomic practices. During 1991, plots were sampled and tested for BNYVV incidence twice between planting and harvest. The second year, plots were sampled once. For comparison, seeds also were planted in the greenhouse and assayed simultaneously with field samples. All assays employed the double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) for BNYVV detection. During 1991, 46 and 50% of field and greenhouse samples, respectively, were positive after 4 wk. After 6 wk, the percentage of plants infected had risen to 57 and 80. During 1992, the higher inoculum rate and longer growing season resulted in >90% infection. We concluded the technique is valuable for establishing infection with BNYVV under both field and greenhouse conditions. It is possible that the method also could be used with other viruses transmitted by Polymyxa spp.