Butternut Squash

My butternut squash plant is huuuge and has 4 squashs growing steadily on it, i didnt pollinate the flowers as the plant is outdoors and i think the insects ahve done it for me!!However the bigger leaves are turning yellow, i keep it well watered but do you think its something to do with all the wet weather, then sun on the leaves after rain?
I dont want to end up removing all the leaves!!!

My butternut squash plant is huuuge and has 4 squashs growing steadily on it, i didnt pollinate the flowers as the plant is outdoors and i think the insects ahve done it for me!!However the bigger leaves are turning yellow, i keep it well watered but do you think its something to do with all the wet weather, then sun on the leaves after rain?
I dont want to end up removing all the leaves!!!

My advice would be not to have the plant too wet. If you have had a lot of rain you will not need to water at all. Too much moisture can encurage various nasties including mildew.

Try pushing your fingers into the soil to check that it is damp underneath... if it is there's probably no need to water. When you water do so when the plant is not in full sun and then try to avoid drenching the leaves too much....as you already said. 

But.... yellowing leaves (just a few older ones) is nothing to worry about as long as the rest of the plant looks green and healthy. Most squash are, as far as I know, greedy feeders so a small handful of pelleted chicken manure helps keep them going.....or some other general fertilizer around the base of the plant.

Apologies if I am "teaching grandma to suck eggs" ...... I find my butternut squash mainly just get on with life on their own......other than the odd bit of redirecting those long straggly shoots..... as well as a slosh of tepid water when the ground is dry. 

Mine's fallen off