Hey brother firstly long time where have you been are you well ?? Sorry only saw this now. Was it not over watered or weather too hot?? I know in this hot climate mine wilt easily and need quiet alot of water in Summer. Strangely though mine have also started going a little yellow into Winter which puzzles me and is a bit of a concern. Those very same Cherries planted in the garden thriving and huge. BONSAI is certainly not natural with soil confined roots fertilizer etc so I guess their "immunity" will never be as strong and the ones grown "more naturally"?? Cheer$;)