i am having to deal with a clients small tree: prunus x snozofam ( snow fountain ).
i've tried to identify the disease or pest... i think it is one of two things:
cherry necrotic rusty mottle
or
prunus necrotic ringspot virus.

i need some advice from anyone who has encountered this and what treatments for this problem i could use, before it becomes a large infestion of whatever it is. i've looked up 'stuff' on internet, but it suggests removal of plants, pointing out that it is stemming from the grafted rootstock, but this is only for fruiting prunus's and this is an ornamental....
i'm hoping someone can help me with some organic advice on what to do.

thanks for you time
leafbird