Is there a reason the ground surroundingnthe tree is bare? Is the area heavily mulched? (I can’t tell for sure, but it doesn’t seem like it to me.)
...So if herbicide had been used, then it’s possible the tree had been affected, though not heavily.
For appearance’s sake, I would probably clip off the “sticks” since even if new needles should grow on them, they are likely to be patchy.
Being same type of tree used for Christmas trees, blue spruce will respond to pruning and shaping. Next spring’s growths will probably balance/even things out.
If it continues to drop needles, then further investigation is warranted. ...hmm... is it heavily shaded on the side it dropped the needles? Do you see similar needle drop on the other tree behind this one? I have a weeping blue spruce (not the cone shaped tree like yours — I Had one of those but it got too huge ...about 15 feet high and 20 feet wide... and then one side of it died, so we took it out), and the weeping spruce loses a certain number of branches every year, especially the branches in the layers overlapped by newer growths. But it is on the east side of the house so I think it doesn’t get enough sun.
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