First spring doing Bonsai and it seems like a crapshoot between pests and and fungi for most of my trees. How in the hell do y'all remedy problems you can't confidently identify?
Three choices: either ID the issue and tackle it effectively.. Or bring in the nuclear option and use broad spectrum antibiotics to kill everything.. Or accept that our own wrongdoings in the past can do a number on our trees and make the best out of it, trying not to repeat our wrongs.
Some things in some circumstances can't be prevented at all. They happen. And I believe it's sound to have some broad spectrum antibiotics/antifungals/antibacterials/anti-insect stuff in stock for worst case scenarios.
But.. They should be a last ditch effort and not the number 1 stop on the road. Because if those last ditch efforts fail at stop 1, stop 2 means certain death for your plant. There are people on this forum who shower their trees with antibiotics - and it works! They have great trees in good health. But there's also people who never do this and have great trees in good health. The former will have no options left if something bad happens to resist the chemicals. The latter have a whole plethora to choose from.
ID'ing what's wrong is a great part of getting better plants and seriously ramping up your understanding: know what hurts them, know how to prevent it, know how to possibly cure it.
Let me walk you through ID'ing an issue.
Historically:
You have chlorotic dead tips on some spots. But now they're overgrown with new shoots. That means something happened in the past. Could've been a repot, a dry day, spider mites, a couple weeks of rain, anything. All we know for sure is that juniper roots are connected directly to branches and that root issues go hand in hand with foliar problems. I don't know your nutrients, I don't know your watering, I can see two pictures and that you're in spider mite country. I don't know cali weather, but I know you guys sometime have some weird snow fall (does that come hand in hand with freezing temps?). When was the tree repotted? Any dormant sprays? Insect sprays?
Visually:
I don't see mottled patterns, grey discolorations or white tips. That means we can exclude spider mites. Can't see the soil, so I don't know anything about that. Can't see the trunk or branches, so I can't tell if there's sap flow issues or any damage. I can't see the pot holes, but if there are no white root tips near it, the tree could've been dry for a while or even overly wet if you find mud near the holes.
Olfactory:
How does the soil smell? It should smell like the tree. If it smells like a lake in summer, something has drowned. If it smells foul, there sure is something bacterial growing in there.
Cues:
Bottoms first: no telltale signs, because there are no pictures.
Trunk and up: same as above.
Foliage: chlorosis on last year foliage starting from the outside inwards, dead tips on weaker branches. No visible black spots, no rust growth, no weird malformations on the branchlets, no aphids or remains of aphids, no visible spider mites.
Chlorosis can happen in a couple of cases: lack of water, too much water, iron blockages (high soil pH), anaerobic soil.
So the natural thing to do is to exclude points: lack of water is out of the question because you use a chopstick, too much water is possible. Do you know your water pH? What does the soil smell like?
How's the progression been? Did the tips turn grey and limp first, or did they just brown up? Have there been any drastic temperature changes a couple weeks, maybe a month or even two, ago?
I don't want to exclude fertilizer burn, because that would have the same signs and the light chlorosis might have nothing to do with it as it can be local (root-foliage connection).
The more answers you can provide, the more logic we can apply to give you an answer.