You may notice signs of the poa trivialis dying (discoloration-yellowing or browning) within 2-3 weeks after you have applied Certainty but it is normal not to see anything for at least a month. Per the product label, you can make an additional application 4 or more weeks after the initial application as needed. Best results are obtained when target weeds are actively growing & not disturbed by mowing for at least 2 days before and 2 days after application. Warm, moist conditions following application will accelerate activity; cold, dry conditions will delay activity. Drought stressed weeds are less susceptible.
Yes, Certainty Herbicide is labeled to control both rescuegrass and poa annua.
Per the Certainty Herbicide product label for dallisgrass suppression, you would use 1.25 oz per acre. This would be mixed in 10-50 gallons per acre. The amount of water you use will vary as the water acts as the carrier. For smaller areas, you would use 5 small (or 1 large) scoop per 2 gallons of water to cover 1000 sq ft. At this rate one bottle will cover one acre. Please refer to the product label for complete instructions for treatment and tank mixing recommendations.
The amount of Certainty will depend on what type of turfgrass you will be applying the product to and the amount of water you use will vary as the water acts as the carrier. On average with herbicides you will use 2-3 gallons of water per 1000 sq/ft to give sufficient coverage. Please click on the product label link for specific mixing and application instructions.