Yes in St. Louis MO you have something to worry about trying to grow Bermuda grass. You are quite a bit north of where Bermuda can thrive, and probably not the best choice for your area. Arkansas/MO state line is about as far north as one should try to push Bermuda. On the flip side unless you have a really cold winter, you are stuck with Bermuda. It will look fine during the hotter summer months, but summers are fairly short in St. Louis Misery, so you can only expect 3 or 4 months of green grass using Bermuda with only 2 of those months being vigorous growth. It is too late now to do much with the Bermuda now, I suspect it has gone dormant or will very soon. You can put out a pre-emergent now to prevent any more cool season grasses from germinating, but I suspect it is too late for that now from your description. When the cooler wetter weather arrived in your area was prime conditions for the other grasses to germinate. If you drive around and take notice you should notice your neighbors cool season lawns look great right now. Anyway go ahead and get some pre-emergence to halt winter annuals, and repeat around Xmas, then again in March. As soon as you see the Bermuda to start greening up next spring start your monthly fertilizer applications. Then when the soil warms up to 70 degrees over seed with a common Bermuda that has very good cold tolerance like Yukon. Or another option is next summer starting in July, nuke the Bermuda with several applications of Round Up through Labor Day, cut the dead sod out, and replant with a cool season grass like Fescue, KBG or a blend.

You have to get the roots of the invader out of the Zebrinus clump. If you cannot pull or tease them out, then you must dig out the clump and remove them that way. This should not effect Zebra's performance this season, especially if new growth has not yet emerged. If you do this, keep the plant watered (moist), treating it as though you have divided it. There is a more drastic measure: systemic herbicide, but ONLY if the Zebrinus is still dormant. I do not recommend it, but it can be done carefully by "painting" the blades of the invader with the herbicide.

I agree that digging the bermuda out and then putting in a garden barrier to keep it from creeping back into the liriope is the most effective way to remove the bermuda grass from the monkey grass area long-term because if you kill the bermuda with a herbicide, since bermuda is such an aggressive grower, it just will continue to infiltrate the liriope over time. For a short term solution, you can use one of the over-the-top weedkillers like Ornamec or Fertilome's Over-The-Top grass killer. I just checked Fertilome's Over The Top label online to verify, and it says it kills bermuda grass. It also lists liriope (monkey grass) as tolerant of the product, meaning that when the product is properly mixed and applied following label directions exactly, the liriope should not be harmed by the product. I do know people who have killed plants with these over the top herbicides by mixing them at a higher rate or applying much more heavily than the label specifies, so be sure you are careful to follow the label directions exactly. Here's the label, which includes extensive lists of plants that shouldn't be harmed by the proper use of the Over The Top product. Label for Fertilome's Over-The-Top Herbicide

Dear BT33 Thank you very much for your inquiry. I suggest you buy a product called Acclaim extra (fenoxaprop-ethyl). It will take out crabgrass easily, and with repeat applications 2-3 weeks apart will knockout the bermudagrass. You will need to go to a turf specialty/supply store (like Lesco) to get this product, I believe. Seeds and stems do travel via vehicles and water. There is little to do to prevent it. It has been happening in nature since the beginning. Again, thanks for the question and let me know if you have more. Respectfully Trey Rogers, The Briggs & Stratton Yard Doctor, YardDoctor.com