Dwarf Norway Spruce loosing needles

Hoping to get some ideas here please.  My spruce has many top needles browning and along with them green ones are also falling off.
I have looked for spider mite, fungus, can’t see anything on trunk, nothing that the eye can detect. I repotted it , pruned it and also used copper in case , also pyrethrum.
It’s been several weeks and still continuing to loose daily . 2 other people have said they have the same thing happening, both have not been able to find a conclusion. We all live in Australia.
 I must also point out shimpaku have been   loosing a lot as well.  However, not all of them as I grow quite a few of these .