Answer: I'd first examine the yellowing needles. Use a magnifying glass to check for tiny black dots (which indicate a fungal diseases). If you find holes in the needles, it indicates damage from the spruce needle miner. If you see webbing on the affected needles, it indicates spidermite damage. If none of the above apply, the plants are showing symptoms of environmental stress (over or under watering). Hope this information helps you determine the problem with your spruce trees!
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