Hello "Ask an Expert", I have seen something over the past few years, and finally thought I should ask someone and see if they know what it was. It probably affects about 1 in 20 tomatoes or so. I do experience the occasional blossom end rot as well, but this seems a little different. It's kind of like the bottom of the inner seed column gets kind of dry and brown. It doesn't seem to affect the tomato too much, I just cut that part out and it seems mostly fine. If there is a way to cut down on this though, I would be interested in finding out how to do so. The variety is "San Marzano". Any thoughts about what this is, and how to avoid it would be much appreciated. Thanks! Todd Holmberg
Hennepin County Minnesota tomato diseases
Thank you for contact us. Your tomato, bottom and along the sides seems to show tomato skin thickening which can be caused by heat or underwatering. Some tomatoes are bred with thick skins (Romas, plums, etc) are bred with thick skins to resist cracking that decreases commercial yield. The San Marzano is a plum tomato.
I hope this helps.