Survival and yield performance of the diploid potato genotypes selected during field trials in the coastal desert area of Lima, Peru, were evaluated under sub-tropical conditions in San Ramon, Peru, in a field with severe bacterial wilt (BW) infestation. Some selected diploid genotypes, which had been found to be resistant also to other biotic stresses in field trials in Lima, showed comparable yields to those of the tetraploid standard local cultivars under the subtropical conditions. Based on analysis of variance, the effects of the resistance to BW on the survival and yield were not consistent. These facts were considered to result from interactions between the BW resistance, adaptation (e. g. heat tolerance) and environmental factors. Observations of the latent infection provided an insight into how the expression of BW resistance is modified by environmental and pathogenic factors under field conditions.