White Poplar seedlings

[Genofish]

I had a large White Poplar that would have a few seedlings pop up in the lawn over the summer.The tree came down in a wind storm. Now due to the tree laying on the ground amd being cut up my yard is invested with poplar seedings where ever the branches were layin, there has to be houndreds of them. I can temperarly kill the seedlings with weed b gone but they come back after 2 weeks. Is there any thing that will kill theme without damaging the lawn or should i dig them out. I attatched two pictures below.

[Tom7227]

Poplars expand in an area via the root structures. When one is cut down or falls the roots kick into high gear to try and replace the downed comrade. There's nothing you can do to stop it, just keep mowing.