Brown spots toward top of stem HELP!

I have a plant that has a brown spots and lines on the stem almost like a thin crust but not quite. Any ideas why this is happening? the rest of the plant, leaves and all are a healthy green color, no yellowing or other signs of ph problems. (hard to see in the picture, but look at the dark areas on stem)

That pic is not good enough, get another one.

If the leafs start yellowish in flowering it usually Cal/Mag def ...
Do u add some epsom salt or cal/mag + yet?
If not add enough cal/mag ASAP ...If not your plants will show u some brown spots and then late to cure the plants ....
Best regards

My camera is awful, thats the best I can do. I have 4 plants in hydro drip system and 4 in soil. This plant is one thats in soil and the only one to have the brown spots towards the top of the stem. If you look closely you will see brown lines on the stem that are almost crusty. I sprayed peroxide on the stem lightly incase it was fungus or mold but after doing that twice it still remains. I just don't want the plant to affect the others if it is a pest or something else bad

I haven't added anything to the plants, I mixed the soil to provide quality nutrients and only have fertizized twice in a month and 1/2. Also this is the only plant that has not stated to flower or show male or female preflowers =/ View attachment 1928761

I used a all around fertilizer and use Mono potassium Phosphate 0-52-38 twice during flowering. Whats Cal/mag? (calcuim/magnissium?) epsom? and where can I find it?

Also one more question for you guys. Should I trim off the bottom branches off these plants? Any tips?

Knyves said:

Also one more question for you guys. Should I trim off the bottom branches off these plants? Any tips?View attachment 1928778View attachment 1928779

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good work ... u can take clone from them