Preventive Approach Advised by PACE Turfgrass Research Institute

On June 21, the Northern hemisphere enters summer solstice. The longest day of the year marks the start of the most difficult time of the year for managing golf course turf. It is a time when long days and short nights result in heat stress. There’s more time for golfers to inflict traffic damage, and there’s less time for turf to recover. Drs. Larry Stowell and Wendy Gelernter, research directors of the PACE Turfgrass Research Institute, advise a strong preventive approach and caution against aggressive management practices that depend on rapid recovery of turf during the summer months. Manage carefully and in small doses, they say, until the autumnal equinox (when day and night are equal in length) arrives September 22. Although hot days occur in the fall, turf damage is less because the nights are longer, cooler and allow more time for turf to recover.

Stowell and Gelernter suggest golf course superintendents review and follow these preventive methods for avoiding summer stress on putting greens:

“Vent” Monthly for a Breath of Fresh Air:

  • Schedule a monthly “venting” (aeration) using small (1/4 inch) diameter hollow cores or solid tines.
  • This practice helps prevent surface sealing and black layer. The small diameter holes are relatively non-disruptive to play, but allow oxygen into the root zone, and enhance water movement.
  • Always check soil salt levels and leach to remove excess salts prior to venting.
  • Because stressed or dying turfgrass takes longer to recover when vented during hot summer months, venting or aeration should be used as a preventive strategy and not as a remedial tool that is used after damage has occurred.

Raise Mowing Heights, Increase Rolling and Use Growth Regulators:

  • Raising mowing heights by even 1/32 inch can give the turf a big boost in its ability to tolerate stresses from pests, heat and traffic. That tiny fraction of an inch is sometimes all that stands between success and a make-or-break summer.
  • To keep greens speeds up, consider rolling up to four times per week.
  • Applications of Primo (trinexepac-ethyl) every 14 to 28 days at low labeled rates will tighten the turf canopy and also help keep greens speeds up.

Keep Turf Cool:

  • Begin preventive cooling programs (syringing, fans, blowers) when turf canopy temperatures reach 100°F for poa, 105°F for bentgrass or 125°F for bermudagrass.
  • The best way to measure turf canopy temperatures is with a digital thermometer and a bead thermocouple (available from Grainger’s or other suppliers for about $150). Monitor at the hottest time of day (usually around 2 p.m.).
  • If you don’t have a bead thermocouple, a quick test for turf canopy temperatures is to place the flat of the palm of your hand on the turf surface. If the surface feels warm, the canopy temperature is probably above 98°F (your body temperature) and therefore close to or within the cool-season turf danger zone of 100°F to 105°F.

Direct Traffic:

  • Change pin placements and avoid traffic in areas that show stress.
  • Route traffic onto the green at multiple locations.
  • Rope off areas before they exhibit excessive wear.
  • Keep the traffic moving by regularly updating traffic flow and pin placements to prevent excessive wear.

More detailed information on alleviating summer stress and other turf management programs are available to members of the PACE Turfgrass Research Institute. A free, three week trial membership, available at, is now available to all interested turf managers.

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