Is there a global setting for DBI that I can set so it knows to convert dates in a certain format?

no. You could have verified that yourself searching   perldoc DBI   for the string "date".
If you do that in   perldoc DBD::Oracle, you can learn a bit more about the solution pelagic has offered you. His answer is the way to go (...ok, taking the string and manipulating it with perl works too...).

Cheers, Sören