Ian from Leander writes
Prime Source Quinclorac 1.5L Select Herbicide will kill crabgrass. However as a general rule, herbicides should applied in temperatures below 85 degrees to avoid damaging the turf. If your temperatures reach higher than 85 degrees during the day, you will need to apply in the early morning or in the evening when temps are cooler.
Answer last updated on: 08/20/2018