It may have just run it's course...in orchards they're replaced fairly frequently here...however, some of the older varieties lasted much longer.

Those stubs left from pruning didn't help the thing at all. A great way to introduce bugs and diseases.

PLEASE STOPPING SPRAYING.. its called polluting.. when you are doing it for no known reason ...

pick a spot.. plant a new one.. and cut this one down in a year or two ... and dont leave a stub ....

BTW .. i had no bloom on any fruits trees in my MI this year due to winter ...

and all the white stuff on the bark is harmless lichens ...

and when your new one gets big enough to prune... learn how to prune properly.. no stubs.. ever ...

ken

ps: there is a fruit forum.. should you wish help in picking a new tree.. and mail ordering it at proper planting time... at the link.. a handy planting guide .. you can do a lot better than buying one at bigboxstore

Here is a link that might be useful: link

I think a lot of your problems lie with the poor pruning the tree has had. Some of those stubs should have been left as fruit bearing branches.
This tree has seen better days. The pruning work has hastened it's demise in my book and is not worth saving.
Mike

are you using sunflower seed? If so, see link.

Here is a link that might be useful: OSU factsheet