As long as the rest of the vine is healthy, I think it's just survival of the vine..it doesn't need to be feeding and watering the old growth, so they die off. I have only seen this happen on my pumpkin vines...they have been very, very healthy...but oldest leaves die...so I can only chalk it up to nature.

It continues to grow well and produces fruit. Ive found it weird and thought it could be something wrong with it.

Yea, I am noticing my pumpkins always look ragged and sections die off. I am an old gardener....but new to pumpkins. I am thinking most of them look ratty after awhile...but I am not sure.

I know this is from last year. My squash are starting to grow and would like to prevent this from happening again. Could it be vine borer damage or powdery mildew?

I could be mistaken, but some of your photos (especially #4) look like mild powdery mildew may be involved. Or your leaves were just dusty. Not sure that explains the dieoff though.

Note that sustaining that whole section of vine running over your porch is costing the plant water/nutrients/work without any return since it isn't able to put down any secondary roots there. I would train the vines only over rootable ground this year if possible and see if there's any improvement.

However, like others have said, it's not unusual for older leaves, or older sections of leaves, to get ratty looking and die as the season progresses. Old age, accumulated sun damage - could be lots of things. As long as you don't feel it's costing you a significant loss of harvest, I'd just try not to worry about it.

I don't have room for them to sprawl over rootable area. We get a small yield of aout 10 or so from 3 plants. Could have been more, my mom picks them before I see them grow.

Yeah, my pumpkin plants always do that. Don't think you need to worry about it.