| Sumario: | Bacterial wilt or Moko of plantain, caused by Ralstonia solanacearum E.F. Smith, race 2, is the most important bacterial disease of this crop in Colombia. The BIO PCR technique was used for detecting the bacterium. A total of 337 samples were initially collected (193 from soil and 144 from plant tissue) from affected crops in six of Colombia s plantain-growing regions. DNA was extracted by thermolysis from 189 strains selected for their growth in SMSA medium; of these, 29 were isolated from soil and 160 from tissue. With primers OLI 1 and Y2, a 288-bp fragment could be amplified by PCR, from the 16S gene of ribosomal DNA in 98 tissue strains and 8 from soil. 64 of the tissue strains and the 8 from soil were selected according to origin and identified as biovar 1 by their production of acids from disaccharides cellobiose, lactose, and maltose, and oxidation of alcohols dulcitol, sorbitol, and manitol. Pathogenicity tests on seedlings of the plantain Africa (Musa cv. AAB) under greenhouse conditions showed that 35 strains were highly pathogenic, 28 moderately pathogenic, 8 had low pathogenicity, and 1 was nonpathogenic. For infiltration in tobacco leaves, 63 strains, induced hypersensitivity, and 9 induced yellowing, an atypical reaction for this race. BIO PCR technique facilitated the detection of the pathogen in soil and plants.
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