The chamomile is an annual, so the pre emergent would affect it, too. Eight acres is a more a commercial-sized application situation. Not knowing your knowledge of pre emergent products, I'm not sure how much to write. Do you understand how the products need to be applied, and when? Are you aware of the $$ required to apply it to an area of that size? I confess, this is more my husband's side of the knowledge base of the business--I generally handle other aspects--and such a large area of coverage has never been applicable.

I admire your ambition to kill off foxtail grass. If it can be done... It is truly a terrible plant because of its awns. A very good adaptation for planting its seeds for optimum sprouting but a plague for animals. I don't know how the coyotes and foxes and other wild mammals deal with a foxtail in their nose or ears, as there is no one to rescue them from the misery.

What will you plant in its place? And how will you keep the foxtail grass from reseeding/contaminating your new planting?

I almost cried while reading your post Heathergillette! 8 acres of foxtails.

I've been battling them non stop on our 1.5 acre yard for 4 years now. Hand pulling preferably early spring while green and soft and just tall enough to be able to bunch them separate from other plants; a recent rain helps too for softer ground. If they've already dried out I just try to clean up and minimize fire hazard but in this state it is not effective since the heads go everywhere - and like the Terminator, they will be back. Echolane brings up an excellent point. As soon as the "heads" are removed the ground must be covered quickly with something else, a deep layer of mulch or gravel or DG or hardscape etc. Weedwacking (the norm around here) just makes them grow more vigorously, since no one seems to pick up the heads which are the start for next years plants. It's amazing to see a dried tiny head take root and sprout into a plant wherever the wind or animals place it. (a bunny lay on our shady covered porch during a heat wave and left behind a foxtail, poor little guy)

This older Houzz thread might be helpful.

I've seen a tool for burning weeds, which would have to be used carefully so you don't start a fire.

Are you able to harvest The chamomile seeds. If so, tandem disc the property. In the fall sow the chamomile seeds.

I would look at Pastora or Tenacity herbicides.

I have a tool for burning weeds but it is very slow process. I had all the fox tails gone and this year they grew everywhere, now I am trying white vinegar spray.

I guess I'm going to stop whining about Bermuda grass now.

Bermuda grass is always a legitimate whine.