By the way I have a 4 gallon backpack sprayer is that going to be able to do the trick. It's a bit of a pain right now trying to kill the lawn, or I should say going slow. Doesn't help that the kids have baseball games almost every night.
I also have a batting cage in the back that gets a bit sloppy because getting a mower in there is a pain. So I weed wack, maybe something like this chemical mowing would be better than moving the net around and weed whacking. The grass in their gets very little sun and it's very sandy.