We present here the results of the field experiments set up on microplots in 2008 at Jadwisin Division of Plant Breeding and Acclimatization Institute. The aim of this study was to assess impact of irrigation on symptomatic and latent ring rot infection of potato progeny tubers. Seed potatoes were inoculated with bacterial suspension of two different concentrations of Cms cells: 10 6 cfu/ml and 10 8 cfu/ml. The most progeny tubers with symptoms of ring rot (1.96%) were found in non-irrigated combination. The share of samples with Cms cells detected using IF test for non-irrigated objects was 76.5%, while for irrigated objects was 89.2%. The latent infection was most intensive in progeny tubers derived from irrigated objects when seed tubers were inoculated with bacterial suspension of concentrations Cms of 10 8 cfu/ml. Irrigation had no significant effect on the degree of progeny tubers infection with ring rot symptoms. The significantly higher degree of progeny tubers infection was determined for samples in which potato seed tubers were inoculated with bacterial suspension of concentration Cms of 10 8 cfu/ml.
