Dallisgrass, nutsedge (nutgrass, yellow an purple), and crabgrass are the most common summer grassy weeds in our area. the pre-emerge that we put on the lawn is designed to control crabgrass, not nutsedge or dallisgrass. Summer grassy weeds must be sprayed after they emerge when the temperature is consistently above 85 degrees, usually after June 1st. Please be patient with summer weed control. Most summer weeds need at least one extra application (no charge in between applications) during the summer months.