Small Pumpkin problem

I have some pumpkins growing,the main vine is long and each have several pumpkins growing along them but some of the pumpkins get to about golf ball size and just shrivel and die.I was wondering if it was because the main vines weren't tipped to create lateral growth or is there some other problem I'm not seeing.We have bees in the veggie beds so I don't think it's a pollination problem.Any help would be really appreciated with my poor pumpkin problem...Thanks.

Have you had a lot of rain? It sounds like a pollination problem but it could also be a fungal problem, or maybe a pesticide in the neighborhood.

Have you had pumpkins before? I wonder if you have the sort of bees who are attracted to other kinds of flowers. Do you have a wide variety of pollinators?

Yeah there was a bit of fungal stuff going on about the leaves Matu,rain hasn't been that extra being summer over here and we do live smack bang in the middle of thousands upon thousands of acre's of cropping farms but harvest is long over and if there is any pesticide spraying it's way off for that also.This is an experimental bed and is covered over with shade cloth so I'm guessing it might be associated with the problem.

We have zuc's & cuc's plus tomatoes all thriving and producing without any of the above problem...kinda strange I thought and as far as pollinators,nope just bees and your normal veggie bed bugs.

Usually with cucurbits if the fruit stays small, then turns yellow and rots then it wasn't fertilized.

Drought or high temperatures can cause plenty of female flowers but a lack of male ones. Plants usually naturally produce less male flowers as autumn approaches.

I'm heading towards that conclusion also Charli Wilson...sorry I haven't gotten back sooner but we've had a bit on our plate with the festive season and all.

I see bright yellow flowers and think nature is doing it's thing and forget sometimes there are certain process's at foot.

Thanks and a happy new year to all.
Glenn.