I have the exact same problem, is there about a 1/2" -2" dead spot on the branch itself which looks like a powdery fungus of some sort. Mine is on about 3 plants which are also situated infront of my fan. I did some research and found out that is could be a "Stem Canker" I cant really find a cure for this but heard of a few people using "DEFENDER" fungicide to prevent it from spreading. Post some pics, I will do the same and we can compare and figure ou a way to get rid of this tear jerking occurance....GOD HELP OUR GIRLS.....LOL