Those firm green-black, gelatinous balls on the greens are Nostoc algae. Nostoc algae thrives in over-watered or consistently moist, sunny areas. Although it is not hazardous to plants or animals, it is terribly unattractive. There are several ways to combat a Nostoc algae problem. Chemical control options provide a control, but cultural control is the most reliable way to win the long-term battle against Nostoc algae.

Causes of Nostoc:

There are various causes that influence the
infestation of algae on putting greens. Some of these include:

  • Over irrigation and extended periods of moisture.
  • Use of reclaimed water.
  • Compaction
  • Low mowing heights
  • Lack of air circulation and shade.

Cultural practices and management of Nostoc:

We have taken various steps to manage the unpleasant appearance of algae in our greens. The idea is to create conditions that are not suitable for the algae.

Step 1: we are keeping the greens as dry as possible for as long as possible. The soil moisture has a big impact in the reproduction and spread of nostoc

Step 2: we are doing weekly vertical mows which promotes air flow through the thatch.

Step 3: following the vertical mow we add a light dressing of sand which promotes drainage and dilutes the thatch layer of the turf.

Step 4: Needle tinning, we have been doing a monthly needle time which also assists with drainage as well as decompaction and allows air into the root zone.

Step 5: fungicide applications are also being applied to assist in combating this.


We believe that with this approach we will win the Nostoc battle. In September we will be doing our annual aeration to the greens tees and surrounds and we hope that this exercise will be the final punch for the unpleasant Nostoc.

Shiraz Mirza,

Bonanza Golf Course
Green Keeper