I don't know if there is an answer to that, Sally, at least not from our experience. We had a LOT of problems with our orchard early on in the form of fire blight that killed off about half of our trees. We sprayed with what the extension office suggested we use, copper and I can't say that it really helped anything at all.
What we discovered is that if we stay away from the hybrid trees and stay with the 'heirloom' varieties, golden delicious, red delicious, candy crisp for example, we get good production and have less problem with insect damage, simply because of the abundance of apples we get from three trees in particular..
The yellow delicous tends to be a poor producer but does give us about a dozen apples every other year that are 'okay' without spraying. They will have problems with black spot and gall but since I usually eat them right away and peel them before eating due to the fragility of my teeth, I can overlook the flaws in them.
You mentioned wild apples? Do these look like miniature red delicious apples? The reason I ask is that we had a tree that succumbed to fire blight that resprouted from it's root stock. Out of curiosity I let the sproutings grow and this year much to my surprise after I cut back the smaller sprouts and left the largest, it bloomed and produced what I can only describe as little miniature red delicous apples that are smaller than a tennis ball. We taste tested one of the apples and sure enough, they taste like red delicious apples and have the same skin and meat texture.
I've tried to identify the root stock but haven't had any luck. I'm going to let it grow and see what happens as heirloom fruit trees seem to be healthier and while the fruit on the 'wild' varieties isn't as large as the regular fruit, you don't have to fuss with them as much.
My best advice is to plant heirloom trees and if you want to spray, spray with organic sprays. Look at Captain Jack products. We used his organic copper spray 5 years ago on our trees when we were trying to save them and we have also used another of his sprays in the past when we had a blackberry arbor with some success in dealing with fruit flies.
Frankly, we just got to the point where we recognized that trees, like chickens were going to die if they set their minds to it and that was when we stopped spraying them. Plus we got aware of the potential toxic effects of the sprays we were using.
So if you want pretty apples, spray with organic and plant heirloom trees. If you just want apples for pies, applesauce and table use, then plant trees with large production factors and hardiness..once again, the heirloom trees such as red delicious, Jonathon, candy crisp, etc.
Better now!
