Hi Gregg, thanks for the question.

I doubt the bread is the problem.  More likely it would be a disease or pest. The squash vine borer would be first on the list. This clear winged moth places its almost unseeable eggs on the base of the plant.  On hatching the larvae eat their way in the plant and then tunnel down damaging the stem so water will not get to the rest of the plant.  Look for wet sawdust like frass coming out of holes at the base of the stem.  Check out the following link:

Squash vine borers | UMN Extension

I hope this helps.