That looks like a lack of pollination. The flower wasn't pollinated, so it died.

George
Tahlequah, OK

2 things can cause this. Insufficient pollination which can be fixed by hand pollinating. And BER (blossom end rot). There is a FAQ here on both BER and how to hand pollinate you'll want to review.

But in this case I agree with George that it is pollination problems as the BER affected fruit usually get bigger than this before it shows up.

Dave

I have been told that once the plants have some squash growing that they will abort additional fruit so that all energy can go to growing those that are already enlarging.

Any truth to this?

That is true. Plants have the ability to protect their ability to reproduce. From their perspective reproduction is the only goal. Once the plant has all the fruits it can bring to maturity, it will abort the rest. That appears to be what is happening in your situation. Pollination problems and BER typically show up early not late in the plants cycle. As the older fruits reach maturity, it may set a few more if the vine is still in good shape. Childbearing takes its toll on plants too.

thanks farmerdilla, if aborting more fruit is what's going on, what can i do about it? is BER something that would happen in may/june (e.g., what would be 'early' in the season)? i guess i'm trying to figure out what to do so this doesn't happen next season.

i attached a picture of my vines - the trellis is 6' tall to give an idea of the scale. as you can see, i planted the squash vines much too close together, and didn't know to prune the runners. would cutting the tips of the vines help set more fruit? i have to admit i'll be disappointed with only 6 butternut squashes! :)

{{gwi:102780}}

Both BER and poor pollination show up with the first fruits. If you have good fruits than later abortions simply means the plant cannot support them. Not much you can do at that point. A vine can only support a finite number of fruits. Stress of course reduces that number, so proper spacing, soil fertility, and water can drastically affect that number. A big healthy vine can support more fruits than than a spindly malnourished one.

thanks farmerdilla, i'll plan my layout a bit better for next year!