Squash can also be subject to BER (blossom end rot) as well as incomplete pollination problems. BER has classic symptoms of initial rot only on the blossom end of the fruit that helps distinguish it from lack of pollination. But if pollination appears to be the cause then trying some hand pollination of the blooms will surely help. Squash vine borers are another chronic problem that you might want to do some research on. They attack the plant itself, not the fruit. ... View related article.
It may be just transplant shock in which case they will recover quickly. But it may also be from excess fertilizer if the stems themselves are curling. Normally it's best to let transplants adjust first before fertilizing. I'd suggest you give them a couple of days in the cool shade to see if they recover, no additional fertilizer or water. You will know within 2-3 days if they will make it or need to be replaced.
Hi Darlene - there are 2 possible reasons. One is called BER (blossom end rot) a common problem in the early spring with all fruiting plants and it has several causes including cool wet weather, too much nitrogen fertilizer, or inconsistent soil moisture levels. You can find out much more about it by Googleing BER.
The other possible reason is called "fruit abortion" due to incomplete or inadequate pollination. It is also quite common early in the gardening year and usually resolves itself once the plant matures a bit more and the weather settles. If it doesn't, you can hand pollinate the blooms for better success.
The way to tell which is the problem is by the size of the fruit. BER fruit will be close to normal size but with a rotted blossom end. Aborted fruit is usually much smaller.
