Can anyone help identify this tox/deficiency?

Hello, the burned tips are caused by too much nutrients and the dark green leaves are indeed a nitrogen toxicity. What you can do is to flush the soil once with 2 times the pot volume in water with the right pH and stop feeding every watering. You can feed every other watering to prevent too much nutrients inside the soil. So you can keep feeding like you are used to but just give water with the right pH in between (water-feed-water-feed). I really like this strain and just grew it myself. The finished product got a beautiful red color. Enjoy your grow buddy!

I checked the diary and I like what you are doing with this plant. I see you know what you are doing so i'll be straight to what I think. To me they look ok, before using actual nutrients i always had burned tips, I wouldn't bother yet if there is no slow/stunned growth, I'd stick to the feeding chart and , I'm not very sure, but I think ph should be very important to you for these nutrients. Your plants problem, based on my experience, is that she is underwatered or she doesn't have ease absorbing the water.

To jump back in here - I forgot to mention that I think the issue is too much nitrogen... the drooping leaves and the really dark green of her are indicators... cut back on your nitrogen-heavy nutes but others can stay at the same strength... :-D

Agreeing with GMSgrows here... you were/are feeding a bit too heavily which has caused the leaf tip to burn... but you don't need to trim off the affected leaves... they're still vital to the plant! My one question, in looking at your diary, is about your EC/PPM ... if you're not measuring that, you really should start - those meters aren't expensive and will help you to determine how much of the nutes you should be giving... You'd be hard-pressed to find a grower who doesn't get those nute-burned leaf tips in any grow - she'll be fine and your instinct to cut back was a good one. Put it this way: a deficiency is MUCH easier to solve than a toxicity.... for me, growing weed, less is more... Good luck!

Hmmmm I personally dont think its a toxicity as I'm pretty sure the symptoms would be bit more severe than this in my opinion. If you have held back on the feed maybe this is a slight sign of an underfeed. As if you overfeed plants you can get burnt tips from under feeding too but its quite strange to be just effecting that fan leaf there are some light leaves but i can only assume this is because you have held back her feed and is probably the start of a nitrogen defiancey but its quite hard to tell my advice ? I would just remove the effected leaf throw it in the bin and then re introduce her normal feed flushing in soil is a very long process so its quite hard to change the feed once you have a good routine. best of luck anyway buddy :)

I would say they were getting a little haevy on the feed, so by cutting back for a while can help out in different ways. If the substrate was building salts then that was remedied. If it was just plain to much feed, then that was remedied as well. I would also check your ph and ec levels from the planter after a watering. Make sure all is dialed in...