There is no herbicide that will distinguish between common and Tif419 Bermuda. You're stuck with it forever. All of us are. Even if you could completely eradicate it in your lawn, someone somewhere is going to let his common Bermuda go to see and some of it will find its way to your lawn. The best we can do is to use cultural practices to encourage the Tif and discourage the common. The Tif thrives with lower cutting. You've already discovered that the common likes to grow taller. Hence, the reason for low mowing. When mowed low, the Tif gets very dense and thick. The common Bermuda is still there somewhere but it kind of gets lost in the thick Tif. A reel mower will allow you to mow down to a half inch or less. Yes, this is better but it would require you to mow every other day. I get the feeling that you wouldn't be too thrilled about the mowing frequency. Mowed at 1", the reel will give a superior cut and it will look better. As far as making the common Bermuda disappear, it's no better than cutting with your rotary. I think your main problem is the once a week cutting. As you've noticed, common Bermuda grows a lot more in a week's time than Tif. Double the mowing frequency and see what you think. I don't know exactly how old that sod is but I don't see the seams. If it were mine, I'd fertilize, water, and follow the Bermuda Bible. It's Bermuda and once established, you can't kill it, as you've discovered with the common Bermuda. Short of spraying RoundUp, you can't do anything to harm it that can't be fixed in a week or two. Feel free to experiment. That's half the fun of growing and maintaining a lawn.

Are you mowing twice a week?Bermuda is suppose to go to seed, especially when under stress from heat and drought. It is just a natural defense mechanism.

The type of bermuda seed is on the back of the bag if you still have it. Completely agree with RJ on mechanical stimulation of bermuda. I'm currently plotting my strategy for next year. A number of golf courses I researched verticut and sand every 2 weeks. The core aerate every month. With that in mind I'm looking to verticut at least three times and aerate x2 next year. From my research, if the lawn is healthy, stable and mature (2-3 years old) you can verticut of aerate anytime during the growing season. So we could in theory be safe upwards of a week or two before out first frost dates. This Winter is my lawn's 1st so I don't know if/when my lawn will go dormant. Your backyard look good. You should do a blanket application of Celsius and Prodiamine (or Dimension) very soon. Kill those weeds and let the bermuda spread a little more be it gets cold. Make sure to do pre-emergent on the front lawn as well. You have a good mower. Check your blade's sharpness and the rolliness of you roller (does it freely/easily spin). Your grass may be laying down longways and not being cut. Even though the mower is set at 1. 25" the actual length of the grass may be long. If you got a few hundred dollars laying around getone of these, otherwise any dime-store ruler will do. Make sure you lightly comb the grass and stand it up before you measure it. You probably can't cut in 3-4 different direction up by that fence which may lead to the grass laying down lengthwise.

So I fertilized with Vigoro Super Green and my grass has greened up nicely. Watering to 1 inch and depth of 6 inches. I check with builder again and I have common Bermuda. I guess they went the cheap route and found cheap ass common Bermuda sod. I mowed my backyard at 2 inches and the reel mower always gets snagged at the brown spots you see in the pic..feels like I scalp it. I know I spreader fertilizer evenly because I did 2 passes at opposite directions. I yanked out a grass stem from a brown spots and a green spot to compare. They both look even in height (so is that technically not a scalp in the brown areas?) however the left one obviously has a lot more green leaf. 1st pic - front lawn 2 inches. Notice that the grass isn't dense. You seem some bare spots. 2nd pic - front lawn 1.5 inches. Cleaner and more level however shows more brown stem. 3rd pic - back lawn. Notice the brown spots. That's always a rough spot for my mower and it feels like I scalp...but look at the 4th pic. 4th pic - comparison of grass from green and brown area in back lawn. Same height yet in obviously has much more brown stem than the other. I compared a few more strands of grass and they are about the same height in both areas. I can keep fertilizing monthly and watering deeply so maybe the front lawn will grow denser with time. What's up with my backyard tho? Brown areas vs green areas. Those spots are always brown. Not much green leaf in those areas usually.