Erik from Martinez, Ca writes
In California many varieties of crabgrass are resistant to quinclorac, which is the main ingredient used to control it across the country. The active ingredient Quinclorac in Drive XLR8 Herbicide Crabgrass Killer is safe for fescue but resistance is possible.
Q4 Plus which is quinclorac and sulfentrazone together for the crabgrass, or Tenacity which is a completely different active ingredient all together. Tenacity though works bests as spot treatments for post emergent control, and the manufacturer suggests only targeting young crabgrass with it as mature large clumps will take multiple applications or may not see complete control when at that growth stage.
Make sure every spring you are using a pre emergent like Dimension 2EW or Pendulum 2G Herbicide to prevent the crabgrass seeds from germinating so you do not have to treat for it later in the growing season. Pre emergents should go down right at or just before soil temps reach 55 degrees consistently.
Answer last updated on: 08/24/2021
