What's killing my veggies?

Last year we planted summer squash and tomatoes (and a few other things). Just before they were ready to pick, the stalks/vines "hollowed out" like something was eating them from the inside out. If we picked the vegetables right away, they were fine, but if we were a day after they were ripe, something was eating them, again from the inside out!

Does anyone have any idea as to what's infesting my garden and if so, how do I get rid of them?

Thanks!