What nutrient issue or disease starts with brown spots on leaf veins?

[nunyabidness420]

I first noticed an issue with this plant when these brown spots started showing up on the veins.
I ran through the usual checklist and couldn't figure out the issue.
Posted on another forum and didn't get an answer.
I ended up harvesting this plant prematurely but I would still like to nail down the issue in case it pops up in the future.
Without out any background information, what do you think this is?

 

[Renfro]

Likely a calcium issue.

 

[nunyabidness420]

Likely a calcium issue.

I thought calcium issues started with interveinal spots.
Do they also start on the veins?

 

[Renfro]

I thought calcium issues started with interveinal spots.
Do they also start on the veins?

I have seen it show up anywhere on a leaf and I have seen it be black dots and white dots.

 

[nunyabidness420]

I have seen it show up anywhere on a leaf and I have seen it be black dots and white dots.

Thank you!
The interveinal thing was throwing me off.

 

[jungle666]

Likely a calcium issue.

Would Epsom salts fix it

 

[nunyabidness420]

Would Epsom salts fix it

Epsom salt is magnesium so I doubt it will fix a calcium issue, but I've read those two are interlinked so
I had EDTA-Ca at the time so a foliar spray would have been my choice of treatment.

 

[jungle666]

Epsom salt is magnesium so I doubt it will fix a calcium issue, but I've read those two are interlinked so
I had EDTA-Ca at the time so a foliar spray would have been my choice of treatment.

What type of folier spray

 

[nunyabidness420]

What type of folier spray

This and water. Maybe some kind of agricultural surfactant if I could get my hands on some.