So I have a kumquat in good condition, nice green leaves, that recovered from root problems a few months ago. Since the new growth is looking very healthy I was hoping one day the scion would grow a new second main branch. Eventually it did, I noticed a tiny new bud growing at the bottom, well above the graft union (yes, I was very sure) but after a week just gently touching it made it fall off. Thing is, it's not from overwatering as it's planted in the full soil and in greenhouse, nor is it showing signs of overwatering ( no yellow leaves and no other leaves are dropping either).
I'm wondering if a sudden temperature increase from the sun suddenly being revealed after a few days clouds + rain and my greenhouse windows being at minimal opening to avoid excessive rain from entering (and the 80Km/h winds from destroying everything) may have caused this, even though it has a shade cloth against the window it's located near.
I really thought new growth should be more resistant, how are citrus in warm climates otherwise be able to grow? O.o (temperature in greenhouse was with clouds 23°C and without clouds 35°C, I have no option for ventilation, I try to open / close windows as timely as possible and yes I know there are automated windows systems, I just didn't take them)