Edit: Additional picture in the comments
My newer tomato shoots are turning black and I’m urgently trying to figure out why. All the plant sites are unanimously convinced that it’s late blight, stem canker or a related fungal issue, but the plant simply doesn’t display symptoms for these diseases- there are no lesions or sores, only a gradual darkening on shoots that is mostly uniform. If I look very closely, I can see many individual (very small) black dots. Any ideas? Thanks in advance!!
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Some plants exhibit a purplish color if the temperatures dip and it produced anthocyanins, I believe nightshades are capable of this.
A reddish purplish hue can also come from too much of a particular wavelength of light as well.
My first thought was cold damage. That’s how my tomatoes look when the temps start dropping at night.
Hard to tell from the picture, but it looks like the tomatoes leaves are going purple too, not just the stem, that’s what lead me to that option.
The plants I deal with don’t express as dots though, so shrug.
Thanks for the quick responses, y’all. Here’s another picture with more to look at- the entire stem is darkening but notice that it’s worst at the top right shoot.
It does look like blight to me but if not it’s likely disease of some kind so I would treat it the same. Carefully remove the affected areas and put them in the trash. Isolate the affected plant if you can. Continue with regular care
Blossom end rot? Hit it with some liquid cal-mag.
