I attended a WSU Master Gardener Clinic this morning and three people came in with the same problem. Cherry Bark Tortrix. Seems to be the season. It has moved down the West coast from Canada to about 40 miles North of the Columbia River and is beginning to move inland. This pest seems to favor Fuji and ornamental cherry but will attack Plum and other plants in the rose family. For more info Google "Todd Murray WSUCBT" This link mentions the Trichogramma wasp that is being introduced to get rid of the moth that causes CBT. http://community.seattletimes.nwsource.com/archive/?date=20011007&slug=homegard07
What I have seen die from it is Prunus x blireiana. The Sato cherry cultivar is correctly 'Shirotae' and not 'Mt Fuji'.