What causes this?

[kath]

For someone who admires a "pretty tomato" it's disheartening to see some favorite varieties afflicted with this yuckiness. I've looked up disorders of tomatoes and the only article that seemed to describe this dry brown corky phenomenon only gave a description and not a photo but it was discussing effects of boron deficiency. When I looked that up, I didn't see any pics that showed what I'm seeing.

Is it something that affects some varieties more than others? So far, I'm seeing it in only some of the fruit on a plant and not on all plants. It is affecting some varieties that I've grown before and yet this is the first time I'm seeing it. The blossom ends of most are just fine and when I cut out the rather large cores, the rest of the tomato is fine. Maybe it's just one more thing caused by our hot, dry weather along with BER, pointy non-pointy tomatoes, etc.? Is there anything I can do to stop/prevent it?

The first photo shows clockwise starting at the top: Copper River, Chocolate Beefsteak, Grandma Viney's Yellow and Pink, Granny's Heart, Monomahk's Hat and Indian Stripe x possibly Daniels in the center- just some of the varieties that are showing this. The second a close-up.

Not trying to make a big deal out of nothing, just wondering if this is preventable, I guess.

Thanks, Tomatovillians!

kath