May I ask why you have a problem with ants?
I grow organically and avoid killing any insects in my gardens that may be useful.
They are like my free garden workers
I do use Roundup tho because as soon as the air hits it it turns into organic matter that's why you can plant a day or two later. Only the RU that gets on leafs and travels to the root zone kills.
If crab and quack grasses were a cash-crop I would be able to quit my job
WM sells a product that has the same active ingredients for much less dough$
"Eliminator® Weed and Grass Killer" ( I seem to remember that it is a little stronger ('-'?)
As pitangadiego cautioned .... since the pseudo stem is a leaf protect it from over-spray.