This is not my plant but the clawed tip looks EXACTLY what I see.
I am confused since I don't see any way that the plant I grow has Nitrogen toxicity (as the article suggests where I found the image).
Some of the lower leaves had turned yellowish, so I was strongly assuming N *deficiency*, but then I found this blog with the picture and the claw and they suggest TOXICITY.
I am feeding my plant that is vegging (about 1 month or so) Floranova Bloom (mind you: BLOOM, 4-8-7) which doesn't have too much N in it anyway, and rather than giving 2ml/L or even 3.75ml/L (which is suggested max strength for "rapidly growing plants" I feed 1.5ml/L, which is actually really, really low. In fact I gave so little nutes the last weeks (in my Hempie buckets/hydro) that my first guess was deficiency but NO WAY for "toxicity"
However, there is just one thing maybe noteworthy to mention: I am feeding Floranova Bloom from my old bottle which is ALMOST empty. There is only like a tiny 10ml or so left now, and the solution definitely started to crystalize a little. (But I can still shake, mix and pour it).
Is it possible that the crystallized remains in the bottle somehow resulted in the nuts having more N or something since I can really in no way understand how I could have N toxicity...