Here is the ugliest tomatoe you've ever seen. All of my brandywines from that plant have some sort of deformity on the bottoms - but none like this.
Looks normal from the top...
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But turn it over and...
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From what I've read, it could be a genetic mutation that affects 1 in 1000 seeds. I suspect though that it is from pushing the season and planting when too cold. Maybe I need to brush up on my hardening-off skills.
In any case, they're still big and tasty