It could be a water problem, or it could be blossom blight/ botrytis blight. I'd start by pruning all of the effected buds, and sterilize your pruner between each cut with a bleach wipe. Decrease water first. If you see the plant start to wilt, then water it a little more.

If the symptoms continue, you have one of two choices. You can continue to prune the effected buds until it clears. It took two years of this method with my Pearl Palace. Or you can prune and spray. Captan will work if it's not too bad. If it starts to spread, look into Decree, which is very spendy, and why I was so patient with Pearl Palace.
Good Luck