Bermuda | Asian Turfgrass Center

Zoysiagrass, bermudagrass, and irrigation requirements

Wed, 20 May 2026 15:13:45 +0700

One of the items in my blog posts TODO file has the heading Zoysia and water use Wherley et al.

“Didn’t I already write about that one?” I thought to myself as I was checking the list. I searched for “Wherley” on the ATC site, and nothing turned up about zoysia and water. Only about DLI.

I checked out the recently updated site search to check if I had written about this article previously.

So here’s that article about zoysia and water use.

Wherley, B., Heitholt, J., Chandra, A. and Skulkaew, P. (2014), Supplemental Irrigation Requirements of Zoysiagrass and Bermudagrass Cultivars. Crop Science, 54: 1823-1831. https://doi.org/10.2135/cropsci2013.11.0753

You can read the abstract to get the main results.

sports-type bermudagrass cultivars (Celebration, Premier, Tifsport, and Tifway) had the lowest irrigation requirement to maintain acceptable visual quality
manilagrass (Zoysia matrella) cultivars (Cavalier, Emerald, Zeon, and Zorro) required the most irrigation to maintain acceptable visual quality
manilagrass “root development was limited relative to bermudagrass and Z. japonica cultivars”
manilagrass required about twice as much irrigation as did bermudagrass to maintain acceptable turfgrass quality

See the related posts below for more about irrigation water requirements, zoysiagrass, and bermudagrass.

“Anyone who’s played golf in Japan will know that many clubs have two greens on each hole”

Wed, 14 Sep 2016 12:57:39 +0000

Fred Varcoe wrote about putting greens on Japanese golf courses in the August 2016 issue of Euro Biz Japan. The article, [Know your greens (pdf, 3 MB)][1], includes some quotes from me about bentgrass, korai, and how balls roll on putting greens.

For more about the two green system in Japan, see:

[The two green system][2]
[Grass species and the two green system][3]
[Golf course maintenance at Japan][4]
[Not the usual everyday maintenance][5]
[Golf in Japan, Mt. Fuji, and the two green system][6]

And kind of on this same topic, but of more general interest, see Paul Jansen’s post on [The Japanese Golf Experience][7]. You’ll see more than just grass: breakfast beer, tiny hotel rooms, hot springs, cold springs, blue balls, green tea, and a volcanic eruption.

Why light is more important for ultradwarf than for bent: my presentations at the Japan Turf Show

Tue, 20 Oct 2015 14:03:31 +0000

I’m giving two presentations at the Japan Turf Show in Tokyo this week. In the first one, I explain why light, by which I mean photosynthetically active radiation (PAR), is more important for ultradwarf bermudagrass than it is for creeping bentgrass. I use data from Tokyo and from Watkinsville, Georgia, to demonstrate this and to point out the difference in PAR between Japan and the region of the USA with similar temperatures.

The slides for this presentation about light are available in English and in Japanese.

In a second presentation, I talk about management of ultradwarf bermudagrass greens, explaining how this species performs compared to creeping bentgrass in Japan, and how it should be managed.

The slides for this presentation about ultradwarf management are available in English and in Japanese.

Distribution of daily light integral (DLI) at Tokyo and Watkinsville in 2014

Fri, 17 Jul 2015 08:47:55 +0000

I discussed photosynthetically active radiation during a seminar this week in Tokyo.

This slide showed the distribution of the daily light integral (DLI) in Tokyo during 2014 on days with an average temperature greater than or equal to 20°C.

I mentioned that one could make an overlay of the distribution of DLI at other locations, and that a distinctive feature of the Tokyo-area climate is that there will be more days with a low DLI than at locations with a similar temperature in the southeastern USA.

In this plot, I show the density of DLI in 2014 for Tokyo and Watkinsville.

The temperatures in these locations were similar in 2014; the mean of the mean daily temperatures was 16°C in Watkinsville and 16.8°C in Tokyo. There were 151 days in 2014 with mean daily temperature >= 20°C in Watkinsville; Tokyo had 150 such days.

For the DLI on those days, however, there is quite a difference. The median DLI for those 150 days in Tokyo was 35.8, compared to 42.1 in Watkinsville.

A Tokyo Temperature Time Series

Fri, 09 Jan 2015 16:39:12 +0000

Following up on the low temperature analyses (first one, second one) as they are related to creeping bentgrass during hot summer weather, I have taken a look at a single location over time. The JMA Tokyo surface observation site has annual and monthly data available since 1876 and daily records available since 1949. So it is easy to obtain the data of interest and make an analysis.

All these data are from the JMA historical weather data page. Here’s the code I used to get the data and make the charts.

First I counted the days each year when the low temperature was 21°C (70°F) or higher. This is an indication of the summer duration, if one thinks of summer in terms of temperatures which will cause problems with creeping bentgrass.

From 1949 to 2014, the trend has been an increase of 0.35 days per year with low temperatures of 21°C or above.

Then I looked at the annual temperatures (low, mean, and high) since 1876.

There seems to be an increasing trend, especially in the mean annual low temperature, which used to be less than 10°C in some years, and now is regularly above 12.5°C. But the annual value is not so useful when looking at heat stress.

August is usually the hottest month of the year in Tokyo, so I looked at the daily data for August since 1949, and calculated the monthly mean high, average, and low temperature.

The chart above is the proper way (or at least a standard way) to look at this type of data, because it includes the scale down to 0°C. One can zoom in on these same data by limiting the range of the y-axis scale, as shown below, and note that there is also an increasing trend in the August temperatures.

Is it hard to grow bentgrass in Tokyo? Yes! There is only a single year since 1949 in which the average low temperature in August was less than that 21°C (70°F) level.

I also looked at the percentage of days during the month of August with a low temperature of 21°C or above.

Generally there will be 75 to 100% of the days in August with low temperatures remaining above 21°C. In fact the last summer with more than 25% of the August days less than 21°C was 1993.

Inventions, Education, and Fun at Japan Turf Show 2013

Sat, 30 Nov 2013 15:24:36 +0000

The Japan Turf Show is one of my favorite events of the year. In fact, I like the show so much that I wrote a remote report for the 2012 show that I could not attend. This year I did attend. I taught a seminar about ultradwarf bermudagrass and how it compares to creeping bentgrass as a putting green surface in Japan.

What are my favorite things about this show? For one, it is fun to meet with old friends. I saw Fujihira-san at the show this year. He and I worked together at Habu CC thirteen years ago, where he was the assistant equipment manager; he is now the equipment manager at a new course in Chiba prefecture.

There is also the education, with six seminar rooms offering concurrent sessions on a range of topics. On the afternoon of the first day, a packed crowd of delegates filled seminar room A to listen to a panel discussion about ultradwarf bermudagrass. The presenters were representatives from companies providing Champion, Miniverde, and Tifeagle in Japan.

Although ultradwarf is a subject of interest, most putting greens in Japan are creeping bentgrass. After my presentation, I had a look at some of the creeping bentgrass on display.

Another great thing about the Japan Turf Show are the products one can find only here. For example, there is the Yabuta Co. drop seeder that can precisely spread seed at rates down to 1 g/m². That is the equivalent of 0.2 lbs/1000 ft², and is especially useful for precise application of creeping bentgrass seed.

Mr. Yabuta showed me one of his new inventions this year, the Cup Dr., which is available in small or large sizes for rolling the area around the cup after changing the hole location.

Then there are the multitude of tines and blades for cultivation equipment. The 4 mm hollow tine (0.16 inches) is becoming quite popular.

With all these tine sizes available, there is no excuse not to calculate the surface area affected at each time of core aerification, and to try to optimize that in a way that will maximize surface area removal while minimizing disruption to play.

If I were a greenkeeper, I would look to remove 5% or more of the surface area at each time of coring, and to do that with conventional tine spacings it is necessary to use 10 mm or larger tines. The 4 mm tines have their place, but are not really useful for substantial removal of organic matter or incorporation of sand into the soil profile.

With all these fun things to learn about, I’m already looking forward to the 2014 Japan Turf Show.

Overseeding Fairways in Japan

Fri, 28 Sep 2012 05:04:00 +0000

Twelve years ago this week, I was working with the maintenance crew at Habu CC just east of Tokyo to overseed the bermudagrass fairways with perennial ryegrass. First we verticut, swept, mowed, swept, brushed, mowed, and swept the fairways to prepare them for seeding. Then we spread the seed. And we did all this without closing the course for a single day.

Immediately after dropping the seed we topdressed the fairways with sand. And then we turned on the water. As you might imagine, keeping the seed moist with frequent irrigation throughout the day was a bit tricky while the course was still open for play.

The results were good, however, and golfers were soon playing on beautiful overseeded fairways, a rarity in Japan where almost all courses have dormant zoysia fairways from October through April.

Preparing for Overseeding Twelve Years Ago in Japan

Thu, 27 Sep 2012 09:04:51 +0000

Twelve years ago, I moved from Shanghai Links Golf and Country Club in China (pictured at right) to Japan, where I went to work as the superintendent at Habu Country Club in Chiba prefecture.

Habu CC has bentgrass greens and noshiba (Zoysia japonica) roughs, which is typical of golf courses near Tokyo, but it is unusual in that it has bermudagrass tees and fairways instead of the more typical korai (Zoysia matrella).

At Habu, one of my first jobs was to overseed the tees and fairways with perennial ryegrass to prepare for the winter when the bermudagrass would be dormant. A new (for Japan) system was being implemented at the course in which golfers would drive 2-passenger Club Car carts on the fairways, rather than using caddy-driven 5-passenger carts that never left the cart paths.

When I first arrived, even though it was coming to the end of a hot summer, the bermudagrass was not especially vigorous. We applied some fertilizer to stimulate the bermuda to grow for a few weeks while the temperatures were still hot, before we would overseed at the end of September.

We began our preparations by verticutting the fairways, then sweeping up the debris. The fairways were mown, and then brushed, and then mown again, as we gradually lowered the mowing height down to 8 mm.

The course remained open for play during these preparations, so we had to do our regular work such as raking bunkers, changing hole locations, and preparing the course for play in addition to our work getting the fairways ready for overseeding.

After the final mowing, we swept the fairways one last time, using all the equipment we had available, and then we were ready for seeding. Coming up in the next post, how we spread the seed and grew it.

Turfgrass in the Ryukyu Islands: report on the special lecture at Ocean Expo Park

Sun, 26 Aug 2012 11:46:38 +0000

Just before typhoon #15, I traveled to Okinawa to deliver a lecture about Turfgrass in the Ryukyu Islands at Ocean Expo Park. And despite the approaching typhoon – now passing Okinawa with winds over 130 miles per hour and with waves 50 feet high – there were 101 people in attendance in a packed room to hear about the turfgrasses of these islands, what makes this such a challenging place to produce good turfgrass (low photosynthetic irradiance), and the four steps that one can implement to optimize turfgrass performance under these conditions.

And people came not just from Okinawa, but also from Osaka, and from Nagano, from golf courses, city councils, landscape designers, engineers, agricultural scientists, to learn about turfgrass management in this part of Japan.

One of the things that was discussed was the climate, and I showed the climatological normals data for Naha and Ishigaki, comparing those cities to other cities where warm-season grasses are grown and demonstrating that there is less sunshine here, therefore making bermudagrass, with its high light requirement, a difficult grass to maintain in these conditions, with manilagrass, or St. Augustine grass, or broadleaf carptegrass, producing a better turf under the reduced irradiance of these islands. The presentation slides are available for download as a PDF here (14 MB).

I also prepared a handout for the lecture, and it is available for download here, also as a PDF file (600 KB).

Of course, with any lecture of this type, I am indebted to the translators, and Ocean Expo Park has excellent staff who translated the handout into Japanese, translated my lecture, and served as amazing hosts for my stay at Okinawa. We had a great time, and I’m looking forward to my next visit to Okinawa.

A Botanical Walk at Ishigaki Island

Mon, 20 Aug 2012 16:12:11 +0000

This short video will be of interest to golf course architects, superintendents, and anyone involved in the management or development of golf courses in tropical and sub-tropical Asia. Cut to just eight minutes in duration, it is a narrated walk along 5 km of Ishigaki island coastline, describing the grasses encountered and showing the ecological setting in which these grasses grow naturally.

Ishigaki has a climate very similar to that of Hainan Island in southern China. Seashore paspalum is overused there (and elsewhere in Asia), despite its high cost of maintenance and well-known propensity to be completely overtaken by bermudagrass and manilagrass. In this video, you can see for yourself why that is, and learn what grass is sure to perform much better in Southeast Asia.

How Much Do Clouds Reduce Photosynthetic Irradiance?

Thu, 16 Aug 2012 19:48:55 +0000

Over the past year, I’ve been doing a lot of research about climate and turfgrass performance, especially as it relates to how much light is available for photosynthesis. You may have seen the climate charts that show the large differences in sunshine hours between cities in Asia and cities in North America and in southern Europe, even when the average temperature is quite similar.

More recently, I’ve used a quantum meter to measure the instantaneous photosynthetic irradiance in Thailand, Hong Kong, and Japan, from sunrise to sunset, and I’ve written a short report that summarizes the results to date. The report shows the data from hundreds of measurements and explains that photosynthetic irradiance is reduced, generally, from 50% to 75% when it is cloudy. This has some bearing on the management and selection of grasses in tropical and subtropical areas with significant cloud cover that restricts the photosynthetic irradiance. Download the five page report here (1 MB).

Turfgrass Mystery: what happened with this bermudagrass in the transition zone?

Tue, 07 Aug 2012 19:05:06 +0000

This is a two part mystery, the first part of which I’ll speculate as to the answer, and the second part for which I’ll ask for expert advice (or guesses!) to find the solution. Above we see a green of ultradwarf bermudagrass in the transition zone of Asia. By transition zone, I mean the area characterized by short but hot summers, and short but cold winters, with temperature average and extremes such that both cool-season (C₃) and warm-season (C₄) grasses can grow, but neither will thrive in all seasons.

Referring to the image above, taken in mid-summer, we see what appears to be healthy grass on the right side of the green, and dead turf (or no turf) on the left side of the green. During the previous autumn season, both sides of the green were healthy and identical in appearance.

After the winter, when the temperatures warmed late in spring and the bermudagrass started to grow, only one side of the green grew. That mystery I’ll solve; the right side of the green has a large amount of organic matter and thus a relatively high nutrient and water holding capacity, while the left side of the green is grown on pure sand, with very little water and essentially no nutrient hoding capacity. It seems that during the winter, it was not cold temperatures that killed the bermuda on the left side of the green, but rather a lack of water, and some type of desiccation.

But here, finally, is the mystery … there are a few isolated areas on the “dead” side of the green that by mid-summer have recovered and are putting out stolons, rhizomes, and exhibiting extensive spreading. How did that happen?

And here is what happened:

On this putting green, changing the hole location the previous year caused some of the some from the high organic matter right side of the green to be changed in hole cores to the pure sand left side of the green. And that is where the grass survived the winter.

Ocean Expo Research Center Special Lecture, 24 August

Thu, 02 Aug 2012 23:07:05 +0000

I’ve been invited to give a lecture about turfgrass selection and management in Okinawa and the Ryukyu Islands. This Ocean Expo Research Center Special Lecture will be held on 24 August from 13:30 to 15:00 at the Ocean Expo Park. I’m excited and honored to be going back to deliver a lecture about some of my latest research. The last time I was there, I was studying the whale sharks. This time, the focus will be on something different.

The Ryukyu Islands have a subtropical climate that is noted for its high rainfall. In fact, I'm here now measuring photosynthetic irradiance, and there is a typhoon passing by that rather complicates my data collection. I found a break in the rain to collect some data earlier today.

In this type of climate, there are multiple species of grass that can grow. Just on the island of Okinawa, we can find Cynodon, Paspalum, Zoysia, Agrostis, Stenotaphrum, Axonopus, and Eremochloa, along with various weedy species, and many sports turf areas are overseeded with Lolium or Poa in the winter. Hawaii is a wonderland of grasses because of its diverse climate and elevation changes. So are the Ryukyu Islands. The challenge comes in choosing which grass will perform the best, and how best to manage that grass, because the climate is difficult for grasses with a high light requirement (such as bermudagrass) to grow well.

In this special lecture, I'll be talking about how we can understand grass characteristics and requirements in the context of the distinctive climate of Okinawa. It is open to the public, and the audience, in addition to researchers from Ocean Expo, will include landscape architects, golf course greenkeepers, city and prefectural officials, and anyone who is interested in this topic. When I spoke on this topic earlier this year at Hong Kong, Dr. John Kaminski called it "one of the best talks" he has seen with "great insights" into why certain grasses perform well and the implications of that.

Since then, I've been botanizing and collecting data at Thailand, Hong Kong, and in the Ryukyu Islands, and this lecture is going to be even better. I hope you can join me at Okinawa later this month.

Why is there cool-season grass in Philadelphia and warm-season grass in Seoul?

Wed, 18 Jul 2012 14:06:43 +0000

We can look at temperature data for Seoul and Philadelphia and we find that the average temperatures throughout the year have almost complete overlap. So we might expect that with such similar temperatures on a month by month basis, the grasses used in those cities would be similar. But while the courses at Philadelphia are mostly cool-season grasses, what we find at Seoul are primarily courses planted to Zoysia japonica. Here is a dormant zoysia fairway near Seoul in early spring.

Why such a different choice of grass when the temperatures are the same? I suggest that it has to do with summer precipitation.

From June through September, Seoul has a higher monthly average rainfall than does Philadelphia, and during the two hottest months of the year, July and August, Seoul has more than three times the rainfall, on average, than does Philadelphia. This combination of high temperature with high precipitation can be deadly for cool season grasses.

Customize the chart yourself to see data for other cities.

Data: korea • Chart ID: ATC_climate_chart_Korea

R version 2.15.0 (2012-03-30) • googleVis-0.2.16
• Google Terms of Use • Data Policy

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Ten Years Ago on a Golf Course in Japan: part 1

Fri, 22 Jul 2011 21:34:21 +0000

I was a golf course superintendent in Japan from September 2000 until August 2001. Now, ten years later, it is interesting to see some of the photos from that year and to remember what it was like. We were working with a maintenance crew of about sixteen people in July of 2001, and I think five people on the crew went on to be golf course superintendents themselves; two interns from the United States, and three of the Japanese crew.

We had a great team. July 22 was a Sunday that year, and on Japanese courses then, it was not typical to have much afternoon or “twilight” play. Golf tended to be (and generally still is) a structured event, so tee times (Japanese courses usually do a two tee start, off #1 and #10) would generally be booked a few weeks in advance, with the last tee times usually set at midday. Even on a busy day, after 14:00 or so the course would begin to clear as the last golfers played their final nine holes.

We were able to get a lot of work done on these afternoons. Soil tests of the fairways showed that the soils were low in magnesium and potassium. We were able to find sul-po-mag (0-0-22) from a Japanese agricultural supply company and apply it to fairways to increase the potassium and magnesium availability. And we had to do a lot of work to manage soil compaction, improve water infiltration, and stimulate growth on the bermudagrass fairways. At the time Habu CC was one of the few courses in Japan that used two passenger carts, and at which the carts were allowed to be driven on the fairways. We were doing about 4,000 rounds per month, all with carts driving onto narrow fairways of this course in the mountains of Chiba. So ten years ago today, we waited until the last golfers had moved off these holes and then worked until the sun went down.

Turfgrass at Okinawa

Wed, 13 Oct 2010 15:48:05 +0000

After last week’s Asian Amateur Championship at Kasumigaseki CC, I came to Okinawa for a meeting of the Okinawa Greenkeeper’s Association. The meeting was held at Unimat Okinawa Golf Club and I spoke about optimizing playing conditions for warm-season turf, the challenges of overseeding bermudagrass greens in the climate of Okinawa, and on my experiences working at the Masters, US Open, and Open Championship this year.

Okinawa has eighteen golf courses and they use a range of grasses, from A to Z, Axonopus to Zoysia, as Dr. Hikaru Akamine from University of the Ryukus told me. I met him yesterday and he provided me with a reprint of an intriguing paper he wrote about morphological characteristics of Zoysia tenuifolia and how to distinguish it from Zoysia matrella. This is something I am quite interested in, as the standard classification involves leaf widths but is not useful in practice. Why? Z. tenuifolia tends to be more narrow-leaved while Z. matrella tends to have a slightly wider leaf, but there actually is a lot of overlap in leaf width with some Z. matrella types having very narrow leaf blades. Dr. Akamine’s paper shows that folded leaves in the bud are Z. tenuifolia and rolled leaves in the bud are Z. matrella.

There are many excellent zoysias here, and that is what I see in the lawns around the pool as I look out from my room this evening. But in visits to two golf courses today, I also saw bermudagrass, carpetgrass, St. Augustinegrass, and centipedegrass in addition to the ubiquitous zoysia. And there is one golf course here with bentgrass greens, while at least two others are planted to seashore paspalum.

I suggested to the greenkeepers here that they establish more evaluation plots on their courses. I think that seashore paspalum may be particularly good on putting greens in the climate of Okinawa, and I made some suggestions in a second seminar today about the management of ultradwarf bermudagrass greens. You will find some dramatic golf courses and a wide range of grasses on this small island.