I'm a beginner gardener, and growing tomato plants for the first time. I need help diagnosing a problem on my stems!
I regrew my three plants from seeds of a small heirloom tomato that I came across last year. All three plants are still indoors and small-ish. I labeled them in the below pictures as A/B/C. Sadly, the stems are all showing signs of deformity, though leaves don't have major issues (maybe a light yellow spot or two, which I plucked off). Plant C's stem was looking healthy until recently, and now it's starting to get that scabby look and lose its hairy quality in the affected area. Is this early blight? Bacteria?
Plant C was healthy looking until recently. Should I separate plant C from the others, or is it too late?
I've learned a lot already through this process and in hindsight probably should've heat treated those seeds. Would love help in diagnosing in the meantime. Thanks!