Thank you for your question. My suspicion is that it is powdery mildew, but there is a fungus detected in the east which is far more of a problem than our ‘nuisance’ mildew. I suggest you take the photos and a sample of the ‘gooey stuff’ and visit a local Extension office. The following webpage gives you locations and hours of those in the metro area: https://extension.oregonstate.edu/mg/metro/have-gardening-question Good luck!

Another expert has suggested wooly apple aphid: https://pnwhandbooks.org/insect/tree-fruit/apple/apple-woolly-apple-aphid Still suggest Extension office visit.