An evolving hypothesis in the TAMU multi-adversity resistant (MAR) cotton program is that microorganisms (bacteria, fungi, and actinomycetes) which are natural components of the plant tissues and root surfaces (symbiotic organisms) play a major role in resistance to diseases, insects, nematodes, and stress. These symbiotic organisms are believed to be selectively favored by cottons in which MAR genes have been identified and intensified, and that the symbionts are effective in causing the plant to resist most adversities. The objective of this study was to further evaluate the effects of symbiotic bacteria isolated from MAR cottons on resistance to the bacterial blight pathogen Xanthomonas malvacearum (E.F.Sm.) Dowson, lint yield, lint percent, and fiber quality of cotton cultivars.