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Vector Relations

Differences in Vectoring Ability and Aggressiveness of Isolates of Polymyxa betae. J. S. Gerik, U.S. Department of Agriculture, Agriculture Research Service, U. S. Agric. Res. Station, 1636 E. Alisal, Salinas, CA 93905; J. E. Duffus, U.S. Department of Agriculture, Agriculture Research Service, U. S. Agric. Res. Station, 1636 E. Alisal, Salinas, CA 93905. Phytopathology 78:1340-1343. Accepted for publication 9 May 1988. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1988. DOI: 10.1094/Phyto-78-1340.

Six nonviruliferous isolates of Polymyxa betae from California, Colorado, Nebraska, and Alberta, Canada, were tested for their ability to acquire and transmit beet necrotic yellow vein virus (BNYVV) and cause damage to sugar beet plants. All of the isolates tested transmitted BNYVV from systemically infected Beta macrocarpa to sugar beet. Infection by viruliferous isolates of P. betae resulted in decreased root weight and increased root branching and root tip mortality when compared with noninfected controls. Nonviruliferous isolates of the fungus decreased the top weight and root weight of sugar beet when compared to controls. Differences in the amount of damage caused by BNYVV were observed when the virus was transmitted by individual isolates. An isolate from the Sacramento Valley was found to be more aggressive than other isolates.