Prowl H2O received a label for pastures last season and we had trials to control large crabgrass in an established orchardgrass field. We tried Prowl H2O rates at 1 to 4 qts/A applied in March and compared that with two applications (first in March and a second right after the first cutting). On sandy soils in Delaware, we needed two applications in order to control crabgrass grasses the full season; even the 4 qts in March did not provide full-season control. The key is to get the Prowl H2O applied before the grasses start to emerge since it will not control any emerged plants. Using Prowl H2O in the spring or summer may limit over-seeding in the fall. Be sure to consider this if you are thinking about fall seeding (or over seeding).