The pitchmark and the divot: the science behind course care

To the untrained spectator, a dent in the green or a clump of grass torn up on the fairway may look like minor cosmetic nuisances. In reality, the pitchmark and the divot are direct physical traumas to the complex ecosystems that make up a golf course. Course care is not only a matter of politeness; it is an essential act to safeguard the biological health of the turf. Understanding the science behind this repair explains why a small effort by the golfer makes a big difference for long-term playability.

The anatomy of the green: a fragile ecosystem

The greens on a golf course are often made up of specific grass species such as Agrostis stolonifera (creeping bentgrass) or Poa annua (annual meadow grass). These grasses are mowed extremely short, sometimes to less than 3 mm. As a result, the plants have very small energy reserves and a limited root system.

When a ball lands on the green from a great height, the impact compresses the soil and the plant cells are literally crushed. This is what we call a pitchmark.

• Direct damage: The compaction of the soil closes off the air pores, depriving the roots of oxygen (asphyxia).
• The recovery period: A pitchmark that is properly repaired within 10 minutes heals fully within 24 to 48 hours. An unrepaired or wrongly repaired pitchmark, however, needs up to 21 days to recover. During those three weeks, a bare spot remains that is vulnerable to invasive weeds and disease.

Why 'flicking up' is harmful

The most common mistake in repairing a pitchmark is flicking the grass upwards with a pitchfork. Scientifically speaking, this motion breaks the remaining root structure of the surrounding healthy plants. As a result, an air pocket appears beneath the damage, causing the grass to dry out and die.

The correct method is the 'push-in' technique: the sides of the pitchmark are pushed towards the centre. This restores the density of the turf without damaging the roots and ensures that the mower the next morning does not pull the plants out of the ground.

The divot: an open wound on the fairway

On the fairway, the damage is often greater. A 'divot' appears when the clubface slides under the ball and breaks loose part of the turf, including the roots and soil.

From a biological perspective, a divot is an open wound from which moisture evaporates and where fungi and bacteria can invade the plant.

• Repair with the 'sod': If the loose turf (the divot) is still intact, it must be put back immediately and pressed down firmly. This allows the roots to reconnect with the soil and rehydrate.
• Repair with mix: On many courses you are asked to fill the divot with a mix of sand and grass seed. The sand provides the right drainage and levelling, while the seed produces a new generation of plants that fills the void before weeds can establish themselves.

The impact of disease and weeds

Unrepaired spots are the primary entry point for Poa annua, a grass species that greenkeepers often consider a weed because it is less resistant to heat and drought than the more expensive grasses. In addition, open patches act as a breeding ground for fungi such as Fusarium. When a fungus settles in an unrepaired pitchmark, it can spread quickly across the entire green via the mowers.

Conclusion

Course care is essentially 'field surgery'. By replacing a divot or properly closing a pitchmark, the golfer helps the plants survive after a mechanical trauma. The science is simple: the faster the density of the turf is restored, the less chance disease and unwanted grasses have to attack the ecosystem. A healthy green does not start with the greenkeeper, but with the player who understands that every repaired spot guarantees the playability of tomorrow.