Do they scrape off easily with a finger nail? If so I think you might have Brown Apricot Scale. Or are they globules of thick sap like stuff?

cut down the tree .. and plant something else ...

been there done that.. many times.. and basically.. given up on growing all the fruit trees .. its just to frustrating ... also ornamental plums... the purple leaved trees ...

btw.. google up gummosis ... it really isnt worth fighting it .. imo ... but it might be years before the tree dies ... actually most susceptible trees are what they call short lived trees anyway.... and guess why .. lol .. yup.. gummosis ...

ken

https://duckduckgo.com/?t=ffcm&q=gummosis&ia=web

It's called gummosis. Multiple possible causes, with which cause is involved in each specific instance varying - try searching the web using phrases like "gummosis stone fruits". Also your nearest USDA Cooperative Extension office can be tried for assistance. Due to commercial orchards being a big deal historically in California Extension has a lot of information about growing fruit in your State.