We have about 12 apple trees. This year all of our apples have very small blemished on the exterior and dark veins extending from the skin inwards. Sometimes the veins extend to the core, other times (as in the photo) the just extend a bit. I am wondering if this is stink bug damage or something else.
Marion County Oregon
Thank you for your question. In the absence of maggots in the center of the apple (which would be an indication of codling moths), this would appear to be stink bug damage, based upon the 'trail' coming from the skin. Here is an Extension article on them: https://pnwhandbooks.org/insect/tree-fruit/apple/apple-stink-bug
But, as you can see in the margin on the side, apples are "home" to many other insects, some of which cannot be detected until being cut open. The internal browning may be a physiological issue, and some apple varieties are susceptible to browning due to low temperatures (http://postharvest.ucdavis.edu/Commodity_Resources/Fruit_Physiological_Disorders/?uid=2&ds=822). Here is another OSU publication with information about pest control in backyard orchards: https://catalog.extension.oregonstate.edu/ec631/html
Since there are few effective methods of controlling stink bugs, removing all fruit and vegetative materials around the base of the tree may be the most effective, as well as being environmentally safe. (This same advice applies to codling moths, which overwinter on plant materials.) Hope this is helpful. Good luck!