What's happening to our tomatoes?

[BEZERKO]

Some of them are cracking and splitting open from the stem. Is it rot? not enough water?

[kfred]

1. Inconsistent water supplies

That's usually the cause. Temps that go very cold at night (unseasonably) and then uneven temps during the day exacerbate it. They're still edible, just ugly.

[bvar22]

2. Uneven watering.

We have the same thing this year.
Drought and hight temps through May and June toughened the skins, followed by drenching rains in Mid-July caused the cracking.....especially bad this year.
Mulching and consistent, regular watering will help, but when we have weather like this year, nothing will prevent some cracking.

UGLY, but the taste is still good. Just cut off the heel, and section out any long cracks.
If the cracks are real deep, and a white fungus appears, or if fluid begins dripping out of the cracks, or you see a brown discoloration in the meat, toss the whole tomato in the compost.

The cooler temps and regular rain has promoted the prospects of a good 2nd crop here.
We were about ready to pull up the tomatoes, but we have a bunch of new fruit, so we are going to let them be for a while.