I asked
@Mr. Krip earlier if he had ever seen a phosphorus deficiency, and he said no. He was giving another supplement however, Purpinator, which is high in P and K.
I purposely have not acted yet, wanting to see how damage on one leaf on one plant started to progress around the room, and because of that patience, I think I see what is happening now.
Here is Gummy Bears, my oldest and largest plant, and the one showing the most reaction to the problem.
Next is Strawberry Cough, the second biggest plant in density.
And lastly, Deep Cheese, also one of the 2 oldest plants in the room, and now beginning to finish out as it is entering its 6th week, and just starting to see traces of a deficiency starting up.
One other plant has always exhibited a bit of a problem that looks like Phosphorus deficiency, and that has been attributed to an aphid problem that destroyed some of the roots early on. She also is having a bit of a problem getting P from what I can see, but other than a couple of crinkled but still mostly green lower fans, she is doing fine.
So, my theory is that as great as Geoflora Bloom is, there is only so much P to go around in a 2 week application. A large hungry plant under a big light could exceed the ability of the microbes to get enough P into the roots/myco so as to be available to the plant, and at this time in the grow the plant simply needs more P and K than at any other time.
While some would write this off as late season "fade", I do not accept the loss of any leaf without knowing why, and how its loss could have been avoided. I am sure that this grow would finish out just fine and the buds would still be glorious based on their present trajectory, without supplementing the base Geoflora nute in any way. That being said however, I HAVE been talked into calling another forum Sponsor's product into play to see if I can mitigate some of this minor damage. I knew that watering by hose was too easy... I am going to mix some terpinator into the next watering, and probably start giving it regularly toward the end for individual plants when I start seeing this. We grow very hungry plants here in MIssouri... it is no wonder that the microbes need a little extra food to work with here at the end.