When I was a child, my grandmother referred to down there as "pit-tow" (I never saw it written, this is just how I'd write it based on how she said it). She didn't speak French, but her parents grew up in French Canada.
I found the terms "pissou" and "petit fond". I don't know how realistic, linguistically, it is that their pronunciations "pissow" or "pteefo" turned into "pit-tow" within one generation, nor do I know whether these terms were common in Quebec in the early 20th century.