I try to stay away from heavy chemical use. I use dormant oil spray in the winter (make sure it’s a kind that is okay to use on junipers) and insecticidal soap once it warms up to take care of scale. I don’t have that many junipers so I have time to remove them with tweezers.
BTW, I’ve gotten to the point where I am more picky about what I add to my collection. The time I spend agonizing over an unhealthy tree is time lost working on my nicer trees. I’ve had to cure my impulses to “rescue” trees; I hate to see nice trees go to waste but I’ve learned (through bad experiences) to stay away from diseased nursery stock. Also, you don’t want to bring a tree home that will infect your other trees.
Be careful of taking what is offered to you as well. I took a juniper someone didn’t want any more, and it was covered in scale. It’s doing much better now, but I’ve had to keep it isolated from the other junipers, which is annoying.
Good luck with your juniper, and as someone else suggested, watch some of Ryan’s videos - he has a lot of recommendations for what types of chemicals to use.
If I didn’t mind chemicals, I’d be growing roses but I do, so I don’t