Turfgrass ecology, part 1: abandoned turf in Japan

These photos from an abandoned golf course in the southern part of the Tohoku region of Japan are fascinating. They show clearly how three different species perform when they are not maintained for 18 months in that climate. From a consideration of the grass performance when abandoned, one can get a good idea of the maintenance requirements for the grass when it is being actively maintained.

These photos are provided courtesy of Mr. Norifumi Yawata, who kindly shared them with me along with some details about this site.

Formerly a creeping bentgrass green, now covered in weeds, but the korai around the green has very few weeds by comparison.

This site, formerly a golf course, has not been maintained for 18 months. One is essentially looking at what happens to 3 species of grass after 2 growing seasons (2013 and 2014) with no maintenance.

The greens were creeping bentgrass. The tees and the collar immediately around the greens were (and still are) korai. Korai is Zoysia matrella – the common name is manilagrass. Everywhere else, the fairways, the roughs, and so on, are noshiba. Noshiba is Zoysia japonica – the common name is japanese lawngrass.

Noshiba in foreground at the edge of the bunker. Korai border immediately surrounding the green. The green surface was formerly creeping bentgrass.

In these photos we see the characteristics of these grasses as they are adapted to this environment. Creeping bentgrass on the green surfaces has been overtaken by weeds. Clearly, creeping bentgrass in this environment seems to require mowing and supplemental irrigation and fertilizer and probably some pesticides in order to persist. It dies quickly without those inputs, or at least it becomes thin, with many voids in the turf that allow for invasion by other species.

The photo above shows a sand bunker in the foreground. Then comes some noshiba with the characteristic autumn symptoms of the wonderfully-named elephant's footprint disease caused by Rhizoctonia cerealis. At the edge of the green surface itself is a band of korai, finer-bladed than the noshiba. And then the green, now a weed patch.

View of an abandoned green complex from a high vantage point, showing the rapid colonisation of a creeping bentgrass putting green by weeds.

The korai and the noshiba both persist at this site for at least two years. It looks like some mowing of the korai and noshiba would get these surfaces back to acceptable condition by next summer. But the bentgrass is beyond saving. Because the korai and noshiba persist, it is evident that they survive without irrigation, and without fertilizer, and that the mowing, and perhaps some weed control, are all that are required to keep them at a minimal level of performance.

The dense korai turf is the most resistant to weed invasion when formerly maintained turf was abandoned for 18 months in the Tohoku region of Japan.

There are various implications of these observations on weed invasion of abandoned turf. This supports something I've written about before: for large areas of maintained turf, it makes sense to use a grass that won't die. Then one will be assured that with minimal maintenance, the quality will be acceptable. And with intensive maintenance, that grass that won't die will be able to tolerate every type of aggressive maintenance, allowing one to produce high performance turfgrass surfaces.

Korai forms a denser turf than noshiba and this is reflected in the relative amount of weed invasion in abandoned turf.

In this case, and at most golf courses in Japan, this good practice of grass selection is used. The creeping bentgrass area is small, less than 5% of the maintained turf area. So the grass that dies, the grass that requires intensive inputs, is planted only on a minimal area. The grasses that don't die, and that require relatively fewer inputs of irrigation, and fertilizer, and pesticides, and mowing – in this climate these are korai and noshiba – are used on more than 95% of the maintained turf area.

Zoysia on putting greens? Why?

Korai green on the 18th at Keya GC during the 2014 KBC Augusta tournament

Why would one deliberately use manilagrass (Zoysia matrella, or korai in Japan) on golf course putting greens? If one would grow bermuda (Cynodon) and korai side by side, and give them the same maintenance, the ball will roll better – smoother, and farther – on the bermuda than on the korai. One can manage korai to get an impressively smooth roll, as seen here, but overall one will see a smoother roll on bermuda than on korai.

So why, then, are there hundreds of golf courses in East and Southeast Asia with korai greens? It has to do with climate. The 2014 KBC Augusta tournament was held at Keya Golf Club in Fukuoka during the last week of August. Keya has noshiba (Zoysia japonica) rough and korai greens, tees, and fairways. Zoysia everywhere. And the conditions there make a good explanation of why one might prefer korai over bermuda.

Clouds above Keya GC on 24 August

There is considerably less sunshine in East and Southeast Asia compared to locations in the United States and Europe where warm-season grasses are grown. Even so, August 2014 had especially low sunshine in Fukuoka. The closest weather station to Keya GC with sunshine data is Maebaru

Mowing a practice green on a rainy morning at Keya GC

During August, there were 75.5 hours of sunshine at Maebaru. Sunshine duration is the time during which the direct solar irradiance is greater than 120 watts per square meter. That's an average of 2.4 hours of sunshine per day during August. And there were a full 8 days in August in which no sunshine was recorded. That is, the direct solar irradiance never exceeded 120 watts per square meter.

Trees around the 1st green at Keya GC

That relative lack of light for photosynthesis does not take into account the further shading caused by trees. As at most golf courses, many of the greens and other highly-maintained turf areas at Keya sit close to large trees.

Pumping water from a bunker on the 1st hole at Keya GC during the 2nd round of the KBC Augusta tournament

During the tournament week, there was some sunshine and plenty of clouds and rain. There were an average of 2.6 hours of sunshine per day during the tournament week itself, and rain fell on 4 of the 7 days during tournament week, for a total of 52.5 mm (at Maebaru).

The 13th green at Keya GC on 30 August

In these conditions, with such a low amount of sunshine, korai grows pretty much close to normal. Sure, it might be a little better if the sun were shining, but the relatively low light requirement of korai allows it to be maintained aggressively even during the cloudiest and rainiest of weather. 

To put this amount of sunshine – 2.4 hours per day on average at Maebaru during August 2014 – into perspective, that's less than London on average in February (2.5 hours) or my hometown of Portland, Oregon, during January (2.8 hours). Portland in January and London in February are not exactly bastions of sunshine. 

Atlanta and Fukuoka are at a similar latitude. On average, there are 8.3 hours of sunshine per day in Atlanta during August. There were zero days in August 2014 with that much sunshine at the Maebaru weather station in Fukuoka.

The reason for choosing korai instead of bermuda in East and Southeast Asia is that korai doesn't die. Imagine growing bermudagrass greens and trying to prepare them for a tournament when the amount of sunshine is less than London in February or Portland in January, or when not a single day for a month has as much sunshine as an average day in Atlanta.

For more about this, see:

More about the measurement of grass clippings

Pg (1)
2 liters of clippings from the putting green

One can measure the volume of clippings collected when mowing greens through the simple process of bringing along a bucket to empty the clippings into.

This technique is used at Keya GC in Fukuoka, the host club for this week's KBC Augusta tournament. The greensmowers bring along a bucket and take note of the volume of clippings collected from each green.

Mowing the practice putting greens at Keya GC

In a previous post, I mentioned some of the ways that this information can be put to use. Here at Keya, the target for tournament week was to be at less than 10 L per green. During the 2013 tournament, the clipping volume averaged 11.8 L per green during tournament week, and 5.3 L per green in the week immediately after tournament week. The course superintendent, Andrew McDaniel, thought that putting surfaces for the 2014 tournament would be best if the clipping volume were slightly less than in 2013.

The clipping volume is collected year round, and from most of the greens. I've taken a subset of the 2014 data and plotted it for the month of August, with the average clipping volume from greens 1, 2, and 4, just to show how the yield has been this month, through this morning, the 2nd round of the tournament.


It looks like the clipping yield is close to the target range. By tracking the amount of clippings, one can adjust nitrogen rate, growth regulator applications, and mowing height and amount of mowing in order to modify the amount of clippings.

The use (or not) of brushes, or groomers, or the effects of various other maintenance practices can be evaluated when the clipping volume data are available. The Shibaura G-EXE22 mowers used on the greens can be fitted with this brush.

Brush fitted between the front roller and the bedknife on the Shibaura G-EXE22

Andrew found that use of the brush increased the number of clippings by a factor of 2. During the tournament, the brushes are not being used, but in the lead up to the tournament, the brushes were used to increase the amount of clippings and help create the desired surfaces.

View from behind the 14th green at Keya GC

Now, during tournament week, the korai (Zoysia matrella) greens at Keya GC are growing at just the desired rate, and the mowers are removing the targeted amount of clippings. It doesn't take much extra time to collect this information, and having a time series of these clipping volume data can help a turf manager make decisions about the adjustments to make in green maintenance.

Korai green surface at Keya GC

Measuring and tracking grass clippings

Many golf courses in Japan track the volume of clippings mown off putting greens using this simple technique. A plastic bucket is brought along on the mowing runs, the clippings are placed in the bucket, the bucket is shaken to allow the clippings to settle, and the volume of the clippings is recorded.


This information can be useful to check, track, and improve the management of putting greens, For example, the data can be used to:

  • ensure that all mowers are set up the same way
  • measure the effect of fertilizer applications
  • measure the influence of growth regulators
  • evaluate the effect of weather and maintenance practices on growth
  • track clipping yield for special events


Andrew McDaniel is the golf course superintendent at Keya GC in Fukuoka, where the Japan Golf Tour Organization (JGTO) holds the KBC Augusta tournament. Leading up to the tournament, the clipping volume of the korai (Zoysia matrella) greens was generally more than 20 L per day per green with a single cut. Today, on the Wednesday of tournament week, a double cut of the greens is collecting about 5 L of clippings per green. The progression to the tournament target clipping volume has been monitored carefully.


He also used brushes on the mowers in the lead up to the tournament. When two mowers were used on the same green, each mowing the green once, the mower with the brush collected about twice as many clippings as the mower without the brush. 

For an even more detailed look at clipping production over time, and different ways I've seen it measured, see my report on clipping yield from putting greens.

Baker Street Botany

Baker_streetI'll retire to my usual haunt to ponder this one. Let me set the scene.

Mid-July, Saitama prefecture, Japanese lawngrass (Zoysia japonica) at the back of a driving range, infrequent mowing, no recent drought, and no recent frosts. Looking down at the grass – for one must be observant – I saw horizontal bleaching or striping on the leaves.

"Aha," I said, "I've seen this before. At Okayama prefecture on the same grass species, in the same season. And I've seen this picture with almost identical symptoms on the same species grown in Florida."

Bleached bands on Zoysia japonica near Tokyo

I inquired about recent weather and drought and herbicide applications. Temperatures have been relatively mild. There has been enough rainfall to keep the grass from experiencing drought stress. The hottest day of the year so far was 1 June, with a temperature of 34°C. That was more than 6 weeks ago, and since then the temperatures have been mild.

Bleached band in the center of a Zoysia japonica leaf near Tokyo

Glyphosate was applied about a month ago, not to this grass directly, but in an immediately adjacent area less than 1 meter away.

Have you seen these symptoms on Zoysia japonica? If so, under what conditions do they appear?

Bleached bands on Zoysia japonica at Okayama

Helicopter spraying

Pine wilt can kill infected trees within a few weeks. The pine wood nematode does the damage, but it is the pine sawyer beetle that spreads the deadly nematode.

Thus, disease measures for pine wilt involve control of the pine sawyer beetle. I learned about this today at Keya Golf Club in Fukuoka. There are approximately 25,000 pine trees at Keya, and helicopter application of insecticide can be completed on all these trees within one hour. 400 L of spray solution are added to the tank, the helicopter sprays that out, and then the process is repeated 3 more times. In total, the helicopter will make 4 runs, each time with 400 L of spray solution.

After observing the spraying from the ground, I got to take a ride in the helicopter and enjoyed a fine view of this classic golf course. 

3 fine football fields

On the eve of the World Cup, I have three quick things to share about football/soccer. 

Kashima Soccer Stadium, March 2014

1. I've been to two matches at the Kashima Soccer Stadium (this was a venue for World Cup games in 2002) in the past year, one at the end of summer, and one at the beginning of spring. The grass is a mixture of 2 kentucky bluegrass (Poa pratensis) varieties and one hybrid bluegrass variety. In this part of Japan it would be typical to use warm-season grasses on sports fields – summer temperatures are similar to those in Atlanta – and on the surrounding golf courses and lawns, warm season grasses are grown. I've been impressed at just how good the turf is here. Almost all the stadiums in J.1 are bermudagrass, so this pitch at Kashima Stadium is exceptional in being cool-season grass, and exceptional in being maintained to such a high standard. 

2. In the Thai Premier League, one can find matches played on bermudagrass, zoysiagrass, and seashore paspalum. Muangthong United play at the SCG Stadium on the north side of Bangkok, and the pitch here is seashore paspalum.

Seashore paspalum at SCG Stadium in Bangkok, April 2014

To keep the ball moving quickly, water is added at halftime. 

Irrigation at halftime, SCG Stadium

This is the best pitch I've seen in Thailand.

3. If you haven't watched this feel-good story about the amazing Panyee FC in an amazing part of Thailand, take a couple minutes and watch it now. I bet you haven't seen football played like this.

Grass species and the 2 green system


Abiko Golf Club near Tokyo won GOLF Magazine's Best International Renovation of 2013 award. In this article about the work, I read that Brian Silva, with co-designer Kye Goalby, "transitioned the old Japanese two-green system – one bentgrass, the other local korai grass – down to one." 

The Club did have two greens before the renovation, but it was two bentgrass greens on each hole, not one bentgrass and one korai.

The greens at the 7th hole of Abiko GC before the renovation

Rather than one bentgrass and one korai green, I've observed that most courses in Japan with the two green system actually have two bentgrass greens. To read more about this, see:

Although courses may have been constructed with one bentgrass and one korai green, most have converted the korai to bentgrass.

Just how common is the two green system in Japan? A survey by Monthly Golf Management magazine in 2013, with results published in The Greenkeeper 2014, provides an answer. Of the 1,176 courses responding to the survey (approximately half the courses in Japan), 37% have the two green system. It is interesting to see how this has changed over time. This table summarizes the survey results.

Year of opening% of total courses% with two-green system
until 1945 2% 36%
1946 to 1969 20 56
1970s 31 54
1980s 15 30
1990s 28 11
2000~ 4 5
overall 100 37

The largest percentage of courses were opened in the 1970s, followed by the 1990s. The percentage of new courses with the two green system peaked in the immediate post-war period and has been in steady decline ever since. Overall, 37% of the courses in Japan, based on the results of this survey, still use the two green system.