We have two neighbors with large live oak trees and consequently we have live oaks that are constantly popping up all over our yard. Hundreds and hundreds of them. The problem is they are a bear to get rid of. By the time you see them they already have a well established tap root that is difficult to get out, and for what ever reason they have a tendency to shoot up right in the middle of our established plants, shrubs (probably to avoid mulch) and then I can't spray them with anything. And these things grow faster than any plant I've ever seen. In addition because they may be in the middle of an established shrub sometimes I don't see them until they are fairly big (several feet) and then they really have a long taproot and root system. I fight these all year and its driving me insane. Is there anything I can do to stop these pesky invaders or kill them? Other than sneaking over in the dead of night and chopping down the neighbors trees?? Not that I'm not tempted...
Getting rid of live oak seedlings
Good luck! Live Oaks spread by runners AND seeds - I have a he double hockey sticks of a time controlling them in my yard! I spray weed killer, mow them, weed eat them, pull them, cover the area with weed blocker, all for naught - it's a constant battle!
Try cutting just above ground and immediatly paint the cut with full strength glyphosate concentrate. Don't know timing for your zone, but nutrients have to be traveling to the roots, not rising as sap does in the spring here.