Just moved into a new house and the previous owners didn't take care of the yard AT ALL. Weeds everywhere. 90% are simple weeds that will probably go away after I dig and relay a couple inches of soil ready for sod, but there are a cluster of 5 really large weeds that I can't identify and don't know how to properly kill.
My plan was to dig them right out, roots and all, to completely remove them. But the roots are huge and go very deep - I dug a couple feet down and they're still going. I have a feeling I will be digging forever to get them out.
How would you recommend I properly kill these weeds? I was thinking of cutting the roots a couple feet down, spraying weed killer in them, covering them in thick plastic and then filling the holes with the soil I dug out.
Images of the weed and how far down the roots go below (I kept digging the roots more than in this photo - but it gives you an idea).