For those not getting adequate insect control, particularly against plum curculio but also plant bugs and are willing to spend a lot of money for a lot of insecticide, one fool proof method is to combine Avaunt and Assail at highest rates. This gets me cleanest possible fruit. Both are available from Keystone and are not restricted. They are granular and should sustain efficacy for years. I suspect if you combine the Assail with Spectracide it will solve any inadequacies of Spec alone.
My thinking is that the Assail is especially useful on the first app. when its’ kickback is most useful. It’s also quite rain resistant. The label discourages using with a sticker, but it still works with the one I use. It also has a relatively short PHI.