In hot areas of the West, summer can take a real toll on bentgrass and Poa annua greens. Turf is often the weakest in low-lying areas where water collects and the soil remains chronically wet. As the turf weakens and density thins, algae gains a competitive advantage and can take over. The algae forms a dense, thin mat layer that sheds water, prevents turf recovery and hinders seeding.
For courses with immediate algae concerns, this mat layer must be broken-up to facilitate recovery. On a recent USGA Course Consulting Service visit in southern Arizona, I saw the agronomy team using a simple and easy hand-held tool to break up the algae crust and place seed in the dimples. Then the team applied a thin layer of sand to protect the seed and help further degrade the algae. They used the rounded side of a bunker rake to lightly work the sand into the thin areas. Seed can be sowed to aid recovery, but experience shows that the existing bentgrass or Poa annua will recover more rapidly than the seed will germinate if, and only if, the algae layer is broken.
For those courses who experience algae problems in the same areas every year, you may want to consider the following long-term prevention strategies:
Turn off the water. Yes, this is a simple and blunt recipe for improvement but it works. Ensure there is no overspray onto the greens from the surrounds, approach or rough sprinklers. Reduce irrigation frequency on greens and/or lower run times on strategic sprinklers to allow these problem areas to dry between irrigation events. Plan to use soil moisture meters and hoses more often.
Remove collar dams. Oftentimes, algae is found where water is trapped on greens due to elevated collars. Lowering the collar or rough elevation is no easy task and you should consider hiring a golf course construction company to complete this work in a timely manner and to ensure the adjusted area ties in well with the surrounding grade.
Regrade the green and green surrounds. While this tactic will require temporary closure of the green, or at least a portion of the green, regrading to provide positive surface flow may be necessary to eliminate low-lying areas that impound water. A qualified architect and golf course construction company should be contracted to complete such a project. Please reach out to your regional USGA agronomist for assistance.
Install a perimeter drain. Courses built decades ago may not have a perimeter or “smile drain” in all low-lying areas around a green, or the drain may have been installed several feet from the edge of the green cavity. Installing a perimeter drain may help the situation, but providing positive surface drainage is more impactful.
It can be frustrating to see areas on a green thin out and succumb to algae every year. In my experience, 90% of the time such areas are located at the perimeter of greens where water accumulates. In the short term, break apart the algae, apply sand and then hand water or use a portable, low-precipitation sprinkler to encourage recovery. In the longer term, change watering practices and facilitate positive surface flow to prevent chronically wet conditions.
West Region Agronomists:
Brian Whitlark, regional director – bwhitlark@usga.org
Cory Isom, agronomist – cisom@usga.org