Answer: It sounds as though one of your trees is struggling - perhaps the soil is more compacted or it doesn't drain as well as it should. If you see no new growth this spring, you may want to dig your tree, amend the soil, then replant. You'll be able to inspect the root system when you dig it, and that should give you some clues as to why it is not thriving. Healthy roots are creamy white inside; dead or dying roots will be brown or rusty colored. If you find dead roots, cut them away before replanting your tree.
Best wishes with your landscape!
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