Both of those blacks have what's called horizontal splitting which is due to too much influx of water after the skin is at it's maximum size so that the skin splits.

There are really three kinds of splitting that are seen.

1)Horizontal splitting which can occur with any tomato variety hybrid or OP and is independent of association with any variety.

2)Concentric splitting; Seen as circles around the stem, usually scar over but can reopen if there's too much water and initiate a rotting sequence. A genetic association with certain varieties, mainly OP's

3)Radial splitting, pretty much the ame as above although the splits radiate out from the stem in a star like pattern/

Horizontal splitting refers to splitting any where's else on the fruits other thean radial and concentric and is due to water influx when the skin can no longer expand.

Carolyn

Carolyn, Thanks so much!

Carolyn has already done a good job of covering the basics re what can cause cracking, and the different types of cracking.

But here are some specific comments re the specific vars you mention in terms of my experience growing them in our climate.

JD's Special C-Tex (is sometimes referred to as JD's Early Black, I think). If you know for sure that it is a different var, pls let me know. I tend to think this is a case of multiple namings of the same var, but let me know if you know otherwise. Anyway, I've found it is not particularly susceptible to the radial cracking that you show, or any other cracking, for that matter.

Same with the Black Seaman. it doesn't tend to crack much for me.

The two most important factors I've found in cutting down on cracking in general are watering evenly (thick mulching helps a lot in keeping the soil evenly moist and cool, especially in our climate), and not leaving the fruits on the vine until dead ripe. Fruits do not need to be left on the vine until dead ripe for the best taste (common myth). It also helps to go thru and pick anything with a decent blush *before* each watering.

Hi sue...thanks for the reply. These are JD's Early Texas Black. I have grown the C-Tex in the past too( not crazy about it like I am the c-tex)I also try and pick at first signs of color, but have tried to net up my tomatoes so I can keep them on vine longer. Sigh, if I am not dealing with leafhoppers, or not enough sun, I am dealing with sun scald!