Indigo ProForce Checkpoint 500SC 5L HerbicideTargeted pre and post emergence control of Poa annua (Winter Grass). The low application rates and high active ingredient loading make Checkpoint 500SC Herbicide a useful economical and an effective option for Winter Grass control. ProForce Checkpoint 500SC Herbicide is a selective herbicide containing 500g L of the active ingredient Propyzamide. It is specifically registered for the pre emergent and post emergent control of Winter Grass (Poa annua)