COURSE CARE
The Dog Days Of Summer … And A Warning August 5, 2014 By David A. Oatis

August is a great time to aerate for several reasons. Bentgrass germinates much faster than annual bluegrass does at this time of year. If you are trying to encourage creeping bentgrass, aerating in August is better than aerating during the Poa-germination window which starts in September.

August is here and back-to-school sales are in full swing, and that means a couple of things to golf course superintendents: the summer help is getting ready to exit stage left, and the days are getting shorter. To date, this summer’s weather has been milder than normal, with only a few short stretches of high humidity and temperatures. Turfgrass regionalUpdateContent systems have shortened as they normally do, but in many cases regionalUpdateContents are still reasonably healthy because the turf simply hasn’t experienced as much stress as usual for this time of year. Perhaps the milder weather this summer is atoning for the weather we experienced last winter. Or, does Mother Nature have another trick up her sleeve?

I remember a couple of “mild years” that turned out to not be quite so mild – 2009 was one such year. The weather was cool and wet until the first week of August. Right about the time courses began to aerate, temperatures skyrocketed and the effect on some turf was lethal. So what’s the point? Most of the turf I have examined in recent weeks has been in relatively good shape, and most of the weak turf I have observed is the result of low mowing combined with traffic on new turf that is still recovering from winter injury. Many of these areas have been plugged and sodded, so the surfaces are slightly unlevel as well, which contributes to mechanical injury. Many greens would benefit from aeration now, and the weather looks like it is going to cooperate. Here are a few points to keep in mind as you grind through the last few weeks of potentially stressful weather and consider upcoming cultivation options:

  • August is a great time to aerate for several reasons. Bentgrass germinates much faster than annual bluegrass does at this time of year. If you are trying to encourage creeping bentgrass, aerating in August is better than aerating during the Poa-germination window which starts in September.
  • For courses that suffered extreme winter injury, grass populations may have changed to a point where August aeration may be especially appropriate. However, keep in mind that the turf is probably still weak, and thatch levels may not be high enough to justify aggressive hollow-core aeration. This could be a result of having topdressed extensively through the spring and summer to help level and fill in damaged areas. So, August aeration may make sense, but you may need to scale back the process to match the health of the turf and thatch-control requirements.
  • Turf aerated in August usually recovers very quickly. Assuming large, hollow tines are used; greens usually heal in two to two and a half weeks with favorable growing conditions. When the same procedure is performed after Labor Day, the turf will take a little longer to heal. Do the same procedure in late September and the healing window will get even wider. Farther north, or on greens that are heavily shaded, aerating in late September means the turf may not heal before next spring.
  • Aeration is a stressful practice and if the turf is weak it will not tolerate it as well. More importantly, weather is fickle and a sharp increase in temperature before or during aeration can increase stress levels dramatically. That is precisely what happened in 2009. The turf was weak, the aerators came out and then temperatures skyrocketed. The combination resulted in widespread and self-induced turf loss.
  • If you aerate in the next few weeks, keep in mind that the process can kick off summer patch and/or anthracnose. Depending on your grass populations, this can be a benefit or a significant problem. In either case, be prepared.

Don’t take these comments the wrong way. August aeration works really well in many cases, and in recent years many golf courses have gotten away from it. Just be sure to evaluate your turf and its health before pulling the trigger on August aeration.

As always, feel free to give our office a call if you have questions or if we can provide some additional information or insight. Best of luck for a successful conclusion to your season.

Source: Dave Oatis (doatis@usga.org)

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