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Delayed Turf Recovery
Brought To You By Cyanobacteria March 16, 2018 By Addison Barden, agronomist, Southeast Region

Cyanobacteria, commonly incorrectly referred to as black algae creates headaches by slowing turfgrass recovery in thin areas.

Several extreme cold snaps this winter and recording-breaking rainfall in February have left some ultradwarf putting greens a little thin going into the growing season. Thin turf is susceptible to one of the most opportunistic putting green problems – cyanobacteria.

Under the recent cool, wet weather, cyanobacteria can quickly form in thin areas and outcompete bermudagrass. This can slow or even prevent bermudagrass recovery. Controlling cyanobacteria before warm weather arrives is important to maximize bermudagrass recovery in thin areas. However, controlling is difficult because the very practices that promote turf recovery – i.e., improving conditions for photosynthesis, water and fertility – also encourage cyanobacteria growth. Utilize the following steps to suppress cyanobacteria before it becomes too big of an issue:

  • Topdress putting greens to shade cyanobacteria.
  • Vent putting greens to increase gas exchange and help dry saturated soils. Deep-tine aeration will also improve infiltration.
  • Fertilize to promote new growth once soil temperatures are warm enough for bermudagrass to outgrow cyanobacteria.
  • Apply products that can help reduce cyanobacteria such as chlorothalonil, chlorothalonil containing zinc, mancozeb, and hydrogen peroxide.
  • Do not apply DMI fungicides as they have plant growth regulator effects and can enhance cyanobacterial growth.


For more information about controlling cyanobacteria on putting greens, contact a USGA Agronomist.


Southeast Region Agronomists:

Chris Hartwiger, director, USGA Course Consulting Service –

Steve Kammerer, regional director –

Patrick M. O’Brien, agronomist –

Todd Lowe, agronomist –

Addison Barden, agronomist –

Information on the USGA’s Course Consulting Service

Contact the Green Section Staff

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