Question: How can I eliminate dallisgrass from my lawn?
Answer: Dallisgrass forms dense, dark green clumps in all types of lawns. Each of its seeds is fertile, so it's very important that you remove the seed stalks as soon as they start to form. They develop really quickly, so that may mean mowing every 4 days during the summer.
With the removal of MSMA from the consumer herbicide market, gardeners lost a valuable ally in eliminating dallisgrass and other grassy weeds in bermuda turf. (MSMA could never be used with St. Augustine turf.)
As things stand now, there is no herbicide that will kill dallisgrass without killing the desirable turf. Your choices are either to hand-dig the dallisgrass clumps or spot treat them with a glyphosate herbicide. You may be able to apply the glyphosate in early spring, once the dallisgrass has greened up and started growing, but before the warm-season grass has started to green. Apply it only to the dallisgrass, as it will kill all other grasses. If you're careful in your application, the permanent turf will fill across the dead area. If you're careful to choose a product that contains only the glyphosate, there will be no residue left in the soil.