Okay, no more magnesium. That's not your issue and you could end up shooting yourself in the foot.
Plae green-yellow is nitrogen def. It's common late in flower and not something to be overly concerned with as long as you are within 3 weeks of harvest.
I seem to remember that PPP is a 8-9 week finisher, so a single foliar feed with a grow nute mixed 1/2 strength should help keep it from getting real bad.

I'm more worried about WHY you are seeing N def that bad, that early, with symptoms of other micro lockout... Check the runoff pH of your soil. I suspect it's not where it should be, and/or that you have a salting problem that will require a flush.
How to flush:
Check runoff pH.
Let's say it is 6.0. Make a jug of plain tap water adjusted to 7.0 to bring the soil pH UP.
Pour 3x the volume of the pot, in equivalent volume of water, yikes that's a terrible sentence, through it.
Then finish by watering with a bloom fertilizer at 1/2 strength and pH 6.7.
You are adding the N with a foliar spray hopefully, so you can use the bloom fert for the post-flush watering.
stinkyattic Reviewed by stinkyattic on . Problem 4 weeks into flower Hi, This plant has featured in these forums a few times. She's a power plant 4 weeks into flower. Growing in soil, PH 6.5. Using bio-bloom ferts. Some leaves, starting at the bottom are going yellow eventually turning completley yellow to a lime greeny sort of colour. I watered 2 days ago with 3 m/l of bio-bloom and a quarter of a tespoon of epsom salts in a liter of good old H2O. I thought it would be an MG problem as the veins on the leaves were still green as the leaf yellowed. I hope to Rating: 5