Good Morning,
There are a few different pests and diseases that attach Black Hills Spruce. The information in the link will give you information on one disease, lirula needle blight:
https://www.canr.msu.edu/news/lirula_needle_blight_found_on_black_hills_spruce

But there a several others. And there is no "one cures all" chemical that will address all of the possibilities. While fertilizer may give your trees more vitality, it will not solve your problem.
Your best resource for diagnosing and treating your tree is to consult a certified arborist. An arborist is a certified and generally insured expert in trees and their problems. He or she can examine your tree and make recommendations regarding the health of the tree, any needed judicial pruning, and whether or not (in his opinion) it should be removed. You can find a certified arborist in your area here:

http://www.treesaregood.org/

Click on "Find an Arborist" at the top of the page; then click on United States from the pull-down menu. Then enter your State and City. This should bring up a list of certified arborists nearest to you. Or you may be able to locate one under "Tree Services" in your local Yellow Pages.

It is possible to send a specimen to the research lab at Michigan State University; however, due to the corona virus, there are a couple more hurdles to jump before getting a diagnosis. They are no longer accepting walk-in specimens, but can be reached by email.

For plant health assessment samples and insect and plant identification, please send a preliminary email to <personal data hidden> with digital images to see if a diagnosis/identification can be made without a physical sample. Please remember to photograph the injury symptoms both up close and at a distance, as well as include details on any patterns, timing, chemical applications, etc. This is the same information typically requested on the MSU PPD submittal form.

I hope this helps.  Thanks for using our service.