Agreed, cheap baby shampoo. The only requirement for the shampoo is that it be clear meaning you can see through it. If it is cloudy, that means it has conditioners in it which cause other issues. And shampoo instead of dish washing soap because dish washing soap is antibacterial. Bacteria and fungi is what we're trying to improve in the soil. Too bad I didn't get back in time, but bermuda is sensitive to the baking soda, too. Even St Aug is sensitive to it but much less than other grasses. Still it is nice to see the crabgrass die such a well deserved black death. I have a totally unproved theory about how the baking soda works. I believe there are protective fungi that live on the blades of crabgrass. Generally they are hydrophobic and shed water as well as most herbicides. But when you prespray with either soapy or sugary water, then the baking soda can actually get right to the fungus and kill it. Without that protection, I believe the crabgrass becomes affected by a bacterial attack which kills it right away. I could be very wrong, but I'm sticking with that for now.

If you already have enough grass in your yard for your needs ( especially if its just for looks) , its better to not struggle with growing grass around trees.

If bermuda grass is the only weed you have then I suppose just a vertical barrier may work. Tho that will not keep it from growing in the walkways. For me, I don't want bermuda grass or any other weeds growing near my beds or in my walkways if possible. So for me it's a combination of prevention and constant maintenance. I also avoid the use of most chemicals near or on anything I will put in my mouth. Right now I have some bugs eating some leaves and things don't look picture perfect but they are not bothering the fruit - so be it. I use dish or hand soap mixed with rainwater in a spray bottle. "Your garden is the only place you will know just what chemicals were sprayed on things". ~ Gumby WANT TO KILL BERMUDA GRASS? A few options may work, but not for everyone.

We have the same issue in our front yard and believe it is gravel put there by the builder. I can't dig in any one spot without hitting the gravel and when I planted a vitex tree a couple of years ago I removed a bucket full of the small rocks in a 3'-wide area. In our case this area is what is known as the "bathtub" part of the yard where water runs in and may stagnate. There is a slight slope that runs down toward our home, so they probably poured the gravel down there to help it drain. It was no doubt compacted by construction machinery also. Despite those attempts this area is still soggy and in early spring is full of slime mold, so the gravel didn't even do what it was intended to do and makes planting any groundcovers very difficult. We put in a drainage tile that helped a lot with the water. The weeds, of course, love this spot. Is your area in full sun? Ours is in part shade which creates added problems because Bermuda does not tolerate much shade. Instead we have lots of moisture loving, shade loving weeds. If you have the sun that is what is giving your turf a fighting chance though the gravel being there will prevent it from really thriving.