Soybean rust caused by Phakopsora pachyrhizi is one of the most serious economic threats to soybean production in South America. A previous study using South American P. pachyrhizi populations collected between 2007/2008 and 2009/2010 revealed the pathogenic diversity in Argentinean, Brazilian, and Paraguayan rust populations. Because such pathogenic diversity has been a major constraint to the breeding program for soybean rust resistance, pathogen populations were continuously monitored throughout the 2010/2011 to 2014/2015 seasons using the same method of evaluating pathogenicity as used in the previous study. None of the 83 P. pachyrhizi samples collected from the three countries from 2010/2011 to 2014/2015 yielded identical pathogenicity patterns in the 16 differentials, thus demonstrating the pathogenic diversity of more recent South American rust populations. Cluster analysis using a total of 145 rust populations from 2007 to 2015 demonstrated that the Argentinean, Brazilian, and Paraguayan populations were not assigned to three distinct country-based groups. The analysis indicated that a majority of South American populations differed in pathogenicity compared with Japanese rust races. The rates of resistance to the rust populations varied among the 13 differentials carrying Rpp genes; the most effective resistance gene was Rpp1-b followed by Rpp5, and the least effective was Rpp1.