3 years in a row now, every time the buds get to a certain maturity and start to weaken with age I get this. It is a form of septoria , I believe. Once the sugar leaves dry into the buds, the buds themselves deteriorate. We are in a severe drought, just hit 106 again the other day, but there doesn't seem to be anything to do to prevent this. I sprayed sulfur earlier this summer and treated with Zerotol, but once the buds get to this point, it seems to be over.