Earlier this year you diagnosed Choanephora rot on my zucchini plant (for several years my crop is minimal, as many fruits start to grow and then turn yellow and mushy before they mature). I took your advice and mulched newspaper/grass clippings underneath this year's plant, and I also sprayed once or twice with Bonide vegetable spray (insecticide and fungicide). This year our crop was much better overall, although we still had some of the prior issues, but now it appears the entire plant has succumbed (you can see in the pictures that the two main stems are withering/rotting), and I'm wondering if it's ultimately the choanephora rot again or if it may have been something else.
Harford County Maryland
This looks like squash vine borer damage. Here's what you need to know and how to control it: http://extension.umd.edu/growit/insects/squash-vine-borer
This is from our website's Grow It Eat It section, which is packed with helpful info on all the vegetable pests and problems.