Not So Fast

By Bob Vavrek, agronomist, North Central Region
September 18, 2012

It’s easy to forget about the losses of turf that occurred on greens during the heat of summer, now that the weather has turned much more mild. Pushing the greens for speed with low mowing heights now can jeopardize any recent efforts made to seed bentgrass into thin and bare areas of the damaged putting surface.

Golfers tend to have very short memories regarding certain aspects of the golf course yet possess the recall abilities of an elephant about others. For example, a considerable number of longtime members clearly recollect the golden era of the golf facility 30 years ago when the greens were always fast and true, and much faster than today. Yet, we all know this simply is not true as green speeds have increased by at least a foot and likely closer to two feet over the last three decades.  

On the other hand, players have very short memories about the record-breaking heat and drought stress that occurred just a short month or so ago, now that milder days and cool nights dominate the weather patterns. Forgotten are the reasons why the old Poa annua greens were a bit slower than usual when mowing heights were raised to keep turf alive during extremely hot weather. Everyone seems to have become desensitized to the brown, dead spots along the perimeter of the greens and the thin turf along the entrance and exit points to the putting surfaces.

Golfers found it easy to be reasonable and patient about turf recovery when it was too unbearably hot to play. The moment the weather turns favorable, golfers immediately have an opportunity to play the course and make up for rounds lost to summer heat. Unfortunately, turf recovery only begins once weather turns favorable. It takes time and gains in turf recovery are never immediate. Golfer expectations for fast greens now will only place pressure on turf that has not fully recovered.

High soil temperatures and cooler nights provide ideal conditions for bentgrass seed germination. The green fuzz of seedlings emerging from the soil can be seen on seeded bare areas of greens within a week. However, the “need for speed” will jeopardize any hope of increasing the amount of bentgrass in damaged putting surfaces. Lowering the height of cut to produce peak season conditions on greens will take its toll on weak and highly vulnerable bentgrass seedlings.

No doubt, there will eventually be recovery across thin and bare spots on greens even if the height of cut is dropped back down to 0.125 inch or less to satisfy green speed expectations, but most of the recovery will be from new Poa annua that germinates from a seed bank already in the soil. Golfers could not care less whether or not the new turf in bare spots is bentgrass or Poa annua. Unfortunately, the new Poa annua that germinates will be dominated by plants that are annual biotypes. Annual biotypes of Poa annua are least desirable because they are highly susceptible to winter injury. And what survives the winter will only then be more susceptible to heat and drought stress compared to either bentgrass or perennial biotypes of Poa annua. Lastly, annual biotypes of Poa annua are most problematic because of heavy seedhead production each spring.  

The take-home message is to keep mowing heights as high as possible as the season winds down to allow damaged areas to recover. Give bentgrass a chance to mature beyond the seedling stage and you may be rewarded with a significant increase in the percentage of bentgrass in the putting surfaces. Patience now can pay dividends by making the turf on greens more dependable in the future. After three consecutive hot summers across the upper Midwest, are you betting against a fourth?

Source:Bob Vavrek, or 262-797-8743


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