I am not sure what that white stuff is. I have seen that on several plants this year. It just sort of looks like you spilled some milk on the leaves and it dried on.
Last fall I transplanted 10 small 2 prong roots up to a patch just off my back yard and one of those came up a 3 prong this year. I noticed that white stuff on it back in May and it is still there today. It looks about the same today as it did back in May and the plant appears to be doing fine. It has not yellowed or done anything that would make you think it was suffering somehow.
Here is a pic of that little 3 pronger in my backyard patch.
Tnhunter I can imagine a day around three o clock when I have been senging all day and I come up on this beautiful water fall,and suddenly im overwhelmed with a desire to just get in there,so splash,im gone,just laying on my back and relaxing,it just couldnt get any better,I love Gods creations.