Cola Turning Yellow! +Rep For ANY Help!!!

One of my 12 plants has a cola that's turning real yellow. This plant has 4-5 colas due to LST and 2 of them have turned very yellow. The other plants of the same strain have not done this.
This is the plant from a distance:

These are the yellow colas:
You can see all the leaves are very yellow, it's not just the HPS light, and the bud looks albino.

And here are some healthy looking colas on the same plant:

If anyone can shed some light on what's going on I will +Rep the hell outta you.

Lookz to me like they need some nitrogen. I give mine nitrogen halfway through flower.

I give a little bit of veg food during 3rd and 4th week of flower so they have been getting nitrogen. Plus Nitrogen is mobile so if it was nitrogen it wouldn't be located at the top of the plant like that. Nitrogen deficiency start toward the bottom or middle of the plant on fan leaves. I've never seen a nitrogen deficiency in only the top cola.

A little more info, my pH of last watering was 6.8. I was in a super hurry so I didn't have time to check the run-off pH, but the time before that the run-off pH was 6.5. I dialed back my nutes a bit from the last feeding, so I don't think it's too much nutes.

It may be a ph issue but I've seen plants hungry for nitrogen where the only signs of it were at the top. Sounds like you know more than me.

they appear also to need more light, or closer to the light, they look like they r stretching. When was the last time u flushed them w something to break don salt like Floraclean?

They definitely don't need more light. I have 100watts per plant, and the lights sit 1-6in away from the top of the cola depending on the plant and how tall it is. This plant in particular sits about 3in away from the bottom of the reflector. I have enough ventilation run through my lights that almost all heat generated by them is extracted.

I've never flushed them using a flushing agent. I water with plain R/O water every other watering but that's it. I don't usually use a flushing agent until the last 2 weeks. Do you think salt build-up on roots is inhibiting nitrogen uptake? If it's a nitrogen problem though, why doesn't the plant take some nitrogen from the bottom fan leaves and distribute it to the top? Nitrogen is a mobile nutrient.

The burning/yellowing of the leaf between the veins is a result of a magnesium shortage. Lots of ways to get those in flowering. I can't see any other problems, but the pictures are a little off...

Snow Crash you sound pretty certain. It does make sense I suppose. I usually give them 1-1.5 Tsp of Cal/Mag+ per Gal when I feed, last time I gave them only .5 Tsp per Gal. Thank you so much for the help.

^I agree with Snow Crash, that's it looks more like magnesium, than nitrogen, evidenced by the yellowing between the veins. IDK though, something is 'off', but I can't quite put my finger on it. To this day, I'm still not convinced that there's such a thing as "light bleaching", bot am not totally convinced otherwise, either. Hmm...are those yellow areas, the areas getting the most light intensity? I'm not sure whether the 'accelerated activity' caused by intense light, brings out deficiences, or what the exact biological cause, is, but I've noticed that during flowering, that's where alot of my deficiences first appear. Even at this moment, there are spots in the areas getting hammered with light, that are a hair lighter in color, than the other tops. I'm thinking that they are photosynthesizing sooo much, that the plant can't 'keep it green', so to speak. IDK, just a theory. I do know that the healthier they are, the less this becomes visible, which seems to indicate that I'm on to something.


IDK if it could be albino traits showing. I haven't had enough experience with the subject, to know if the trait can show up so late. Anybody?