Burkholderia solanacearum race 1 isolates indigenous to the French West Indies were characterized by bacteriocin typing and two genomic fingerprinting methods: pulsed-field gel electrophoresis of genomic DNA digested by rare-cutting restriction endonucleases (RC-PFGE) and PCR with primers corresponding to repetitive extragenic palindromic (REP), enterobacterial repetitive intergenic consensus (ERIC), and BOX elements (collectively known as rep-PCR). The survey comprised 24 reference strains and 65 isolates obtained from a field trial in Guadeloupe in 1993. Comparison of the data identified RC-PFGE as the most discriminatory method, delineating 17 pulsed-field gel profile types. rep-PCR and bacteriocin typing identified nine rep-PCR profile types and nine bacteriocin groups. Independent determination of similarity coefficients and clustering of RC-PFGE and rep-PCR data identified six groups common to both sets of data that correlated to biovar and bacteriocin groups. Further study of bacteriocin production in planta gave results consistent with in vitro bacteriocin typing. It was observed that spontaneous bacteriocin-resistant mutants exhibited a crossresistance to other bacteriocins as identified by the typing scheme and that such mutants possessed a selective advantage for growth over isogenic nonmutants in the presence of a bacteriocin. The results are significant in the search for biological control of disease by nonpathogenic mutants of the wild-type organism. Burkholderia (syn. Pseudomonas) solanacearum E. F. Smith is the causal agent of bacterial wilt, one of the most devastating bacterial plant diseases in the tropical, subtropical, and warm temperate regions (24). Although the name Burkholderia solanacearum was recently proposed (48), the taxonomic position of this species remains unclear (16). With the advent of modern molecular DNA technology, significant advances have been made in the description of the species in recent years (5, 6). These techniques in general have complemented the previous classifications based on carbon utilization (biovars) and host association (races) and have further elucidated the probable origin of the races observed. Relatively few studies have centered on ascertaining diversity within a race, a biovar, or field populations of B. solanacearum (14, 15, 38). Numerous protocols have been applied to typing bacterial populations, including multilocus enzyme electrophoresis (22, 35), bacteriocin typing (19), and genomic fingerprinting (14, 15, 27, 30). Production of bacteriocin has been reported for several genera of plant pathogenic bacteria: Agrobacterium (26), Clavibacter (10, 18), Erwinia (11), and Pseudomonas (47).