Since I posted the information on the amount of Bermudagrass showing up in Iowa, I have had a number of questions on how to kill it. Roundup is the standard answer, but it is very hard to kill. I have also heard from former students in Bermudagrass country about its control. Below are two recommendations. Notice that these come from other states and that pesticide labeling and recommendations vary by state. Check labels for use of these products in your locations.
The first is as follows:
In our region, we use a combination of Roundup and Turflon (Triclopyr) Ester.
Tank mix Roundup is 3oz/1000ft2 and Turflon at 2oz/1000ft2. Be careful with seeding cool-season grasses back into the area. If seeded within 3 days, you'll see about 50-75% germantion on the cool-season seed. If you wait 2 weeks, you'll see anywhere from 75-100% germination.
(You can also find a number of articles on the internet about using Turflon Ester to control Bermudagrass.)
The second from another location includes Roundup and Fusilade in a tank mix, followed by Tupersan.
The aggressive way of killing Bermudagrass is to apply Roundup at 4 oz/1000 ft2 with Fusilade at 2 oz/1000 ft2 in a tank mix combination. It may take a repeat application
You can then use Tupersan at 14-16 oz /1000 ft2 as a follow up. Tupersan will hold back the Bermuda and you can seed into it.
Again, check label recommendations for your area before using these approaches.