Chris Froome is part of the team announced by the British registered squad but Cummings has been left out, while Thomas is only first reserve.
The nine riders selected are: John Lee Augustyn (South Africa), Francesco Bellotti (Italy), Diego Caccia (Italy), Felix Cardenas (Colombia), Gianpaolo Cheula (Italy), Christopher Froome (Great Britain), Robert Hunter (South Africa), Paolo Longo Borghini (Italy) and Mauricio Soler (Colombia).
Because Barloworld was not selected for the Tour de France, the Giro d?Italia is the team?s biggest goal of the season. They hope to win stages with sprinter Robbie Hunter and do well in the mountains with Maurizio Soler and Chris Froome.
Thomas finished the Giro del Trentino last week, his first race since crashing out of Tirreno-Adriatico, but team manager Claudio Corti was not convinced the young Welshman has recovered enough to face a three week major stage race.
?I?m disappointed but there?s not much I can do about it,? Thomas told Cycling Weekly.
?I gave it everything to recover from the crash in Tirreno but it was always a race against time. I rode Trentino and suffered to get through. I thought I?d done enough but they preferred to select some one else.?
Steve Cummings won two races for Barloworld in 2008 and won a stage at the Giro del Capo in South Africa in March. However he failed to finish Liege-Bastogne-Liege on Sunday after working for his team mates and Corti justified his selection by saying other riders are currently on better form.