Grafted Dwarf Apple Tree Help Needed

[BlackBinder]

Hi everyone,
New gardener here with a mini grafted apple tree question.

I have 3 year old apple tree purchased from a nursery. It is in an 26 inch half oak barrel container. Last year it produced maybe 3 apples and seemed healthy. This year it has many more apples on all of the different grafted branches but something is wrong. Some of the leaves are turning colors and/or getting spots and dying. Please help me figure out what is wrong and what I can do to help it?

The types of grafted branches are: Melrose, Yellow Delicious, Honeycrisp, and Gravenstein. All are semi-dwarf and we live in Oregon if that makes a difference. Thank you all for your time.

[JONA]

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