Too much water and humidity, the leaves crack, and the water oozes out and dries. What you seeing is the white stuff you see on pots that is left over from the water. Trim off the end of the stems, (pinch back) don't water and let the new leaves grow clean, if it is humid don't water. The plant will absorb what it needs from the air.
They do not do will with your growing conditions, it actually hates it and that is the only way it can tell you that something is wrong. Norma

This is the critical time, cut back on water, and put plant in bright shade. These next two months will be the critial months. Hold way back on water at this time. No peat moss, nothing that holds water and builds humidity.
At this time of the year we hare having 105F to 108% we think is will cool down in the next two days, our humidity is up as well. I really think the next 3 mo. will be critical, but the plant back about Oct 1 when you see a cool down trend. It like to be crowded in the pot in order to flower,it likes cool night down even 30F it will tolerage a light frost if it isn't wet, you will see batter colors at this time of the season as well.
if you have time look for previous posts regarding'Jade plants' There has been enough written this past year to write a book, hint, hint , hint to all of you who read this. I haven't been responding to 'Jade' questiions. Norma

I have a jade tree. Its about 3 feet tall. Last year it was so amazing, now it is balding. A month back, leaves started turning black and started dropping. Nursery said may have over watred it, we are letting it dry but still falling. Some leaves have begun to dry. It is about 10 feet away from air conditioner. Have read a lot about it, would like to save this amazing tree.