Dock Weed

The speedy weedy works for dandelions, but not this "dock" stuff that has taken over areas of the yard. This picture was found on Wikipedia. Supposedly this invasive bugger can throw out as many as 40 000 seeds! No wonder my turf looks lousy, it is infested. Boiling water, pickling vinegar, slashing, pulling, yelling, sign language, all have been vain attempts at eradication. The roots on this plant are tuberous and yellow, and seem to be about four feet deep. I have now resorted to chemical means of killing. I feel guilty, but, what can you do? I would rather have no grass at all, and have wildflowers, but, it can look extremely messy and unkempt at certain times of the year.