Crabgrass is an annual plant that normally dies in the fall. Where you live you might not have a fall season that will kill it. Generally you keep crabgrass out of the lawn by mulch mowing at your mower's highest setting. Crabgrass needs FULL sun to thrive. If your St Aug is tall enough, it will shade out the crabgrass and it will never get started. It is not too late to start that if you want. The other way to keep crabgrass from getting started is to let the surface of the soil dry out between watering. Letting it dry out for one week between watering is good. Two weeks is better. Of course you have to water very deeply for that to work. The crabgrass seed needs water every day for a few days in a row to sprout. Many people with in-ground sprinklers will water for 10 minutes each day. If that is how you are watering, then you should expect crabgrass and other weeds until you change your timer. If you really want to try a chemical, try this one developed in Florida. I would not apply it the way they show you in the video - too much waste. I would pour it into a sock and pound the powder out of the sock with my hands for a much lighter application. Supposedly crabgrass turns black and dies in a couple days leaving the St Aug alone to fill in where the crabgrass was. The ingredients in that product looks like a cake recipe to me. Seems perfectly safe.

Hiring someone is out so it looks like we may be digging it up ourselves. I thought about chopping it low, then either trying to dig it by hand or round up it to death. Problem is I do have plants nearby I don't want any chance of being poisoned and I'd like to use the space for replanting so I've been hesitant on the round up. Do you have any idea how deep the roots might be? We just removed some stumps from three rose of sharons I chopped and round upped to death but we had access from the road so we hooked on to the stumps with my truck but this clump of grass is in the back so not so much access to it to pull it up.

Fire ants make mounds and not holes. The mounds start out small and become larger as the colony population increases. These mounds look rather innocent until you disturb them, and ALL of the ants boil out of the mound all at once. Again, there is never a discernible hole. I never worry about ants in my yard and garden, other than fire ants. Fire ants can be a problem for humans, pets, bird nests, beneficial insect eggs and larvae, and such.

crabgrass starts out as small clumps - just like shown on last photo. It quickly gets larger and eventually puts out many many seeds. this would be my guess in this case. It is easily pulled (when young) with very thin roots (another good indicator). Recommend pulling before it puts down more seed. Otherwise a weed killer with Quinclorac will hurt/kill it (not sure about Bermuda safe... or not?) Quackgrass on the otherhand spreads by underground roots/rhizomes... can form some dense areas with thick bright green blades (reminds me of st aug. grass)