Brian from Central Oh writes
Unfortunately, since Dallisgrass is closely related to Tall Fescue, generally what kills one will kill the other. We normally recommend hand pulling, if possible, or using something like Roundup QuikPro to spot treat the Dallisgrass, and then reseeding with Tall Fescue once the Dallisgrass is gone. We recommend using something Dimension as a pre-emergent for you to try to help prevent having to control as much with a post emergent down the road. Often with a few years of fall and spring applications you can get decent prevention.
Answer last updated on: 08/24/2016