Crabgrass breaks are occurring in landscapes this year due to the previous wet weather. The following is information on using quinclorac (Drive) herbicide for postemergence crabgrass control.
Drive herbicide (quinclorac) is safe on Kentucky bluegrass, perennial ryegrass and tall fescue. Consult the label carefully for use on bentgrasses and fine fescue. Drive can be effective on 2-4 tillered crabgrass but for the most consistent control Drive should be applied to crabgrass prior to two tillers. Drive is also highly active on large multi-tillered crabgrass but only when it has entered its reproductive phase (visable seedheads). Drive will not control goosegrass. Drive is tank-mix compatible with broadleaf weed herbicides. For optimum activity Drive must be applied with methylated seed oil (MSO). Two formulations are available: Drive 75 DF and a new liquid formulation Drive XLR8 1.5 L. In some studies we have observed more consistent crabgrass control with Drive XLR8 compared to Drive 75 DF.
Combination Products: A number of combination products are currently being marketed such as Q4, Quincept, and Onetime, which contain Drive in combination with broadleaf weed herbicides or in the case of Q4 also contain sulfentrazone for suppression of yellow nutsedge. Consult labels carefully to determine if a spray adjuvant is recommended. Also determine the use rate of quinclorac (the active ingredient in Drive) you will be applying. Applying quinclorac at less than 0.75 lbs ai/A and/or without a spray adjuvant such as methylated seed oil may reduce the consistency of crabgrass control especially if the growth stage has exceeded one-tiller.
Information from Dr. Stephen E. Hart, Associate Extension Specialist, Weed Science, Rutgers University