Answer: I suspect that there may be two things at work, one being competition from the pine trees' roots for nutrients and moisture, and the other being too little sunlight. The cherries really do best in all day sun or with at least six or seven hours of sun including the hour of noon. That being the case, I am not sure fertilizing will solve the problem. There is a possibility, if the mulch was woodier rather than predomininantly bark, that there has been some temporary nitrogen loss. You might run some soil tests and see if the pH or nutrients are out of line, then fertilize based on the results. In any case, a layer of about three inches of mulch is all that is needed. Allow this mulch to rot down sufficiently and then maintain a thinner layer.
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