Summertime Weed Control in St. Augustinegrass Lawns

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Summertime weed control in St. Augustinegrass lawns can be difficult. Grassy and broadleaf weeds with differing lifecycles and susceptibility to herbicides can frustrate homeowners and lawn care companies alike. Maintaining dense turf is critical, but herbicides will still be needed to limit weeds.

  • Cultural controls:
    • Frequent mowing at 3.5-4"
    • Minimize shade
    • Maximize drainage
    • Fertilize during the spring and summer when St. Augustine is growing aggressively
  • Preemergence (PRE) herbicides:
    • In areas that St. Augustine grows, weeds likely germinate throughout the year
    • PRE herbicides create a barrier that kills young seedlings as they germinate
    • PRE herbicides are the most efficient and most effective herbicides, reducing the need for frequent applications
    • Specticle® from Bayer has longer residual control than other PRE herbicides
    • Specticle is labeled to control 97 common broadleaf weeds, grassy weeds and annual sedges
  • Postemergence (POST) herbicides:
    • Broadleaf weeds that have emerged and become established in lawns must be controlled with selective POST herbicides
    • Celsius® WG is a broad-spectrum POST herbicide with three active ingredients (thiencarbazone + Iodosulfuron + dicamba)
    • Celsius controls more than 125 broadleaf and grassy weeds in St. Augustine lawns, eliminating the need for tank-mixing multiple herbicide
    • St. Augustine has excellent tolerance to Celsius
    • Watch for the upcoming addition to Bayer’s herbicide line-up: Celsius XTRA which will provide the outstanding broadleaf weed control you’ve come to expect from Celsius, plus now control of sedges
  • Pay special attention to label precautions – Effective summer weed control is difficult and comes with some risk of injury to the turf, so read and follow all label instructions
  • Need more info? – Read and follow all label directions. Contact your Bayer area sales manager if you need assistance


dollar weed 

Dollarweed is a perennial can spread throughout a St. Augustinegrass lawn if left unchecked (Bayer)



  Green Solutions - St Augustine Lawn Calendar
Todd Lowe

by Todd Lowe , Todd Lowe, M.S., Green Solutions Team

Monday, April 19, 2021