I have this on one plant in my garden and one plant only. It's Reserva Privada's OG#18. I transplanted two weeks ago into a 20gal so there is no way it's root bound. No one I know has a clue as to what it is, but it has been a problem for me with only the OG#18. But it's such good pot! It may be a humidity problem because I'm at 25 - 30% here. I prefer plants that grow well in all conditions, dirt and hydro.