Brown rot of potato is a devastating disease caused by Ralstonia solanacearum (RS) (Smith, 1896; Yabuuchi et al.1995). Traditionally populations of RS were restricted to southern states since it is unable to infect and survive under temperate climate conditions. Increases in temperatures within potato growing regions and an influx of emerging temperate-tolerant RS populations are two major factors that could potentially affect potato production within the Northern US. Finding potato cultivars with resistance to this pathogen is important as disease is eminent and could be disastrous. The objective of this study is to evaluate resistance within potato species, cultivars, and accessions to populations of RS that are pathogenic at low temperatures. Eight Solanum species (S. brevicaule, candolleanum, chacoense, gandarillasii, tuberosum subsp. andigenum), nine S. tuberosum hybrids from the International Potato Center collection, seven common US cultivars, and the sequenced potato (RH89-039-16) were tested for this study. Pathogenicity screening was done in environmental chambers at 18°C and 30°C, and tests were repeated three times. Plants were inoculated with RS strain UW551, sequevar 1, phylotype IIB, a strain classified as a Select Agent due to its pathogenicity in potatoes at low temperatures. During the study, we found a large variation to brown rot resistance. However, the resistance in most cases is broken at warm temperatures (30°C). Some cultivars showed resistance that can be used for breeding purposes and to mitigate disease in fields by cultivar rotation.