Northwest Indiana. Pumpkins were planted at the end of May. I noticed within the last 2-3 weeks the stems on both plants started turning yellow and the skin started breaking open (for lack of a better term).
Plants are in full sun. Get watered once in the morning and once at night. No fertilizer beyond what comes in the bag of Miracle Gro soil I mixed with our native (clay heavy) soil.
Researching pumpkin diseases (https://www.gardeningknowhow.com/edible/vegetables/pumpkin/diseases-of-pumpkins.htm & https://plantvillage.psu.edu/topics/pumpkin/infos/diseases_and_pests_description_uses_propagation) none of these seem to line up with what my plants have.
I thought I was possibly over-watering the plants, but pulling back to only watering once a day only causes them to wilt (then pop back to life when I water them). I read that leaves can turn yellow if you under-water the plants, but I feel like I've been watering them well (shower setting on the hose sprayer, 2-3 minutes, watering the stems and not the leaves)
Any assistance is appreciated. Linked are photos of the stems. https://i.stack.imgur.com/55Qvf.jpg
Edit 7-23-20: I added a few more pictures. Someone on another forum suggested it was squash vine borers. I haven't seen any of the insects around that look like that though. Also digging around in the ground around the plants I didn't notice any tell tale signs the borers where there.
Edit 7-23-20 #2: The more I'm looking at my pictures the more I'm thinking the bugs have already done their damage and moved on. Looks like I'll be performing surgery on my other squash plants that are showing signs.
Edit 7-23-20 #3: I found spots on the stems of my yellow squash and zucchini plants this evening and decided to investigate. After cutting and scraping at the spots I found no evidence of bug activity. For lack of a better descriptor, they seem to be rotting. My questions are thus: 1) Am I not looking in the right location for the borer bugs? 2) Could this be a fungal or bacterial issue? Pictures at the link: https://i.stack.imgur.com/SCuQL.jpg