First Grow! (Blackberry Kush CBD Auto)

Did some defoliation and some low stress training for a little while, but the latter is no longer necessary seeing as light appears to be penetrating the whole of the plant in my grow room. There are some strange things happening with a few of the lower fan leaves. The plant sticks I have in there do have a green residue that comes off of them (not sure what it is, though they are plant sticks, so I assume they're safe and non-toxic) and I am wondering if that could have caused the crumbling away I'm seeing on one or two leaves. What does it look like to you guys? Few leaves with discolouration too, nitrogen deficiency, perhaps? Been watering her 1L once every 2 days on average (with nutes one watering followed by without nutes the next). Please let me know your thoughts. Thanks!