Thanks...Having flashback to last summer. We had a heat wave down here. 90 days straight above 100 F, some peaking out ~115 F. That may explain it. Even inside the greenhouse with the chiller running full blast, it was tough to stay cool. Although it did stay significantly cooler than the blast furnace conditions outside. The gh topped out at ~ 90 on the really hot days.
I wonder if the heat was/is the culprit. The plant hangs from a rafter near the chiller, so it's at the top of the gh. I have fans running in there 24/7 through the summer.
I have been using the MSU fert for several years now with great overall results. Are there other micro nutrients that I need to be conscious of?