A fall broadleaf weed control strategy is essential in a sports field playing surface maintenance program. The main focus of a late fall weed control application is to address winter annuals and other broadleaf varieties.

Although weed control is relatively straightforward with a herbicide program, the best way to minimize weeds is to maintain a thick and dense stand of turf by adhering to sound cultural practices.

Mowing

  • Maintain turf within the recommended mowing height for that species of turf.
  • Mow frequently and remove no more than one-third of the leaf blade during each mowing event.

Aeration

  • Core aerate at least once a month with a power take-off (PTO)-driven aerator.
  • If budget and time allow, aerate—core or solid tine—monthly.

Fertilization

  • Fertilize native soil cool-season athletic fields with three to four pounds of nitrogen per thousand square feet per year, as some weeds like clover are indicators of low nitrogen.
  • For cool-season turf, apply the majority of the fertilizer in the fall.
  • For warm-season turf, apply most of the fertilizer when the turf is actively growing.

Herbicide Applications

Fall applications provide the best broadleaf weed control due to the downward translocation of carbohydrates. Broadleaf weeds are getting ready for winter and moving resources to the roots. Herbicides will go along for the ride, impacting the roots and other underground structures, thus killing the plant completely and achieving better, long-lasting control.

Some excellent cool-temperature herbicides include 4-Speed XT, Cool Power, and Escalade. Products containing the active ingredients quinclorac or mesotrione will be effective, too. Difficult weeds like ground ivy and wild violet are best controlled with a product containing triclopyr, like Boulder 6.3 EC, by Alligare. 

Consider using an adjuvant to enhance the efficacy of your spray. If you’re planning on reseeding, be sure to check the label of your product of choice since many herbicides have a 10-14-day waiting period between applying and seeding.

Rainy and/or cloudy conditions can reduce the effectiveness of your application. Try to apply your herbicide on a rain-free, sunny day. Fall applications can be made until air temperatures drop into the lower 40s, which is when the weeds will shut down for the winter.

Tips for Effective Herbicide Applications

  • Always read and follow label directions.
  • Adhere to mowing recommendations before and after applications.
  • Remember that liquid applications consistently outperform granular weed control applications.
  • Do not apply herbicides to drought-stressed turf.
  • Consult the label before application if new seedlings are present.
  • Consult the label before application if new sod is present.
  • Pay close attention to overseeding windows after application.
  • Apply in low wind conditions.
  • Use a product containing carfentrazone in cool conditions.