Poison damage: fire and forget ?

[grandmaster]

Hi! I'm new to WD and wanted to ask one simple question:
What is the radius in which poison DOT on enemies is maintained ?
I.E. if I use the passive which grants infinite time to locust swarm(LS), fire LS on enemy and move let's say, 10 screens from that place, will the damage on that enemy still be calculated ? Or not ?

 

[Artemis]

I've leveled up because of a monster dying from locust swarm on another rift floor. I don't know if Blizzard has since patched this long distance killing feature.