Disable Particle Emission When Out Of Distance

So in my scene I have upwards of 70 - 100 particle systems, each for a tree. They all emit a max of 2 very very low poly meshes at a time. I've been using a LOD Group component on them so when the players out of range they aren't rendered, but because they can collide with the world, using LOD component is pretty much useless. What I ideally want to do is disable their emission when I'm out of the particle systems range, but I can't seem to find an efficient way to do this. It's also to be noted when active the particle system drop the games average fps by around 50 - 25 frames. Any suggestions on how to accomplish this would be great, thank!

 

If the particle system is in world space, you could just move one of them from tree to tree, and Emit manually. This would give you really high performance as it's only one system, and culls itself.

But yeah, you'll want to sort out some sort of trigger detection.