A few years ago I wrote about how everyone knows zoysia grows slower than bermuda, except when it doesn't. In particular, I was discussing the growth of the nuwan noi variety of manilagrass (Zoysia matrella) in tropical Southeast Asia.

One of the examples I used in that post was the expansion rate for patches of nuwan noi in the bermudagrass fairways at the Santiburi Samui Country Club. I was back at Samui this week, and I went to the 18^th hole to check the nuwan noi.

Just around the dogleg, and down the hill near the landing area, there is a large patch of nuwan noi that has overgrown the bermuda.

I paced it off, and the diameter of that particular patch is now 17 meters. If that started as a single plant in January 2007, and has now grown 8.5 meters in every direction, then the expansion is 850 cm in 125 months, or 6.8 cm per month.

This approximate rate keeps coming up in a number of measurements I've made. I have estimated the expansion at 7 to 8 cm per month. And in pot experiments, I get a similar rate too. For example, planting nuwan noi stolons at a rate of 1,500 nodes per square meter gives 1,500 nodes in 10,000 cm². If each node occupies 1 cm² at the start of the month, and then the coverage goes from 1,500 to 10,000 cm² by the end of the month, that's an expansion rate of 6.7 cm² for each plant in a month.

Why does this matter? Because I've hypothesized that the most sustainable grass for a given location is the one that has the most growth per unit of N and per unit of H₂O applied.

I went for a run to the ocean at Cerro Gordo. As is my wont, I looked for grasses along the way. There were lots of zoysia lawns where I started. Then I got on a trail and headed down to the water.

When I stopped along the ocean's edge, I enjoyed the view, but I didn't see any zoysia. I was reminded of the rocky shores of the islands in Okinawa. But in Okinawa, one will find lots of zoysia growing on the rocks and cliffs.

This is on the western tip of Ishigaki Island. Lots of zoysia growing wild. Why is the zoysia growing wild in the East China Sea, South China Sea, and Philippine Sea, but more in maintained turf areas in the Caribbean Sea?

I think the answer lies in the combination of light and temperature. Specifically, locations with a longer duration of time at high temperature combined with low light will have a prevalence of zoysia. These locations may also have zoysia that grows faster than bermuda (Cynodon) or paspalum.

I looked up the combination of temperature and sunshine hours on this customizable chart.

Locations on the chart to the right are hotter, and lower on the chart have less sunshine. The "trails" for each location trace the normal combination of temperature and sunshine for an entire year.

I looked up cumulative precipitation too. This should have an effect too, although for competition between species in managed turf, precipitation should be less important, because irrigation can be supplied.

I'd like to grow different species of grass in representative climates and measure how much they grow. I expect certain species would map to location, somewhat like the locations are separated in the chart below by temperature and light.

This poster for today's field day describes what happened when we planted five grass varieties as stolons and then supplied irrigation with different amounts of salt in the water. I think two things might surprise you. First, some of the grass varieties, including a particular manilagrass (Zoysia matrella), can reach full coverage in about one month after planting. Second, irrigation with salty water, so long as enough is applied, doesn't slow down the growth of many warm-season grasses.

When the grasses can grow like this, it shows that managing the problems with water quality are closely tied to the quantity of water supplied. I will be talking more about this tomorrow when we are back for another day of seminars.

I've been growing grasses in a plastic house with a lot of help from colleagues at the Thailand Institute of Scientific and Technological Research (TISTR). The idea was to see how these grasses grow in after being planted as stolons, and to see what happens when salt is added in the irrigation water. I'll be discussing this experiment at the field day in Chonburi next week.

The picture above shows the grasses that receive the irrigation with 330 ppm total dissolved solids (TDS), 28 days after planting. The seashore paspalum looks the best, and the nuwan noi manilagrass has grown-in almost as fast. The hosoba korai, which is a beautiful grass once established, still hasn't covered much of the pot.

Another thing I've found interesting is measurements of salinity in the soil with the new TDR-350. All the pots are supplied with the same quantity of water. But different sets of pots get different amounts of salt in the water.

The soil salinity in these pots is changing depending on which irrigation water is applied. That's just as expected.

For more about the TDR-350, see this webinar.

Related articles

Surprises, conservatism, and what one can learn from soil testing: part 1

"One aspect of golf that we never promote is the health aspect"

Combining temperature and light to compare location effect on turfgrass growth

These pictures were taken 28 days apart. Here's what the grasses looked like yesterday, on February 24. That was 4 weeks, exactly 28 days after planting.

On 27 January, five different grass varieties were planted from stolons. The grasses, shown from left to right, are:

• manilagrass (nuwan noi)
• tropical carpetgrass (yaa malay)
• seashore paspalum (salam)
• manilagrass (hosoba korai)
• bermudagrass (Tifway 419)

For the first 10 days after planting, all the grasses were irrigated with 330 TDS (total dissolved solids, in units of ppm) water. For the next 18 days, the grasses shown above were irrigated with 4,500 TDS water.

The planting rates for the stolons ranged from 99 g/m² for the nuwan noi to 312 g/m² for the yaa malay. This is the mean mass for the stolons planted in the pots. We cut the stolons into 10 segments with 3 nodes each and then weighed them and planted them; each 0.02 m² pot was planted with 30 nodes (1,500 nodes per square meter).

This is what the pots looked like immediately after planting, on January 27.

I think this is interesting for two reasons. One, this gives some indication of the grow-in rate (and relative rates) of various grass varieties. Second, this shows the tolerance or not of the grasses to different salt levels in the water.

One set of grasses is getting water with salt (TDS) at 330 ppm, the one pictured are getting 4,500 ppm, and another set are being irrigated with 9,000 ppm.

I'll be talking about this, and showing some of these grasses, at the upcoming Sustainable Turfgrass Management in Asia conference.

The recording of my webinar on preventing nutrient deficiencies is now available in the videoteca section of the Campus del Césped website.

Or watch the English version right here.

This was fun. I hope you'll read the handout too. It is only 4 pages, with lots of white space, and gives a brief overview of this important topic. If you are still interested, then watch the video of the webinar at your leisure, and watch or download the slides too.

Links in English

• Handout in English
• Video in English
• Slides in English

Links in Spanish

• Handout in Spanish
• Video in Spanish
• Slides in Spanish

I'm bombarded at this time of year with reminders, notices, descriptions, and articles telling me about the importance of frost delays. Apparently, frost delays are essential for the health of the turf. Allow play on frozen or frosted turf, and the leaves will turn brown and start to die. In a worst case scenario, recovery from the damage could take months.

This is a story about something completely different. How about no frost delays at all, and removal of snow by any possible method so the course can remain open? That's the approach used at well over 1,000 golf courses in Japan. I guess there are about 600 courses that are at such a high elevation or are so far north that they close for the winter; at the remaining courses, golf is a year round sport.

I will admit, I was terrified to allow play on frosted turf when I was a superintendent in Japan. I'm sure I protested, explained how much the grass would be damaged, said I would not take responsibility for the damage, and so on. But much to my surprise, the damage was negligible and temporary.

I wrote about how temporary the damage is in this post about winter traffic on frozen bentgrass. As a follow-up to that, I was asked if it mattered if it was a leaf frost or a ground frost. I said I didn't know, but I would look up the temperatures from that winter and share some more details of my experience.

Here's the story.

This was at Habu CC in Chiba prefecture. The greens were Penncross creeping bentgrass, the tees and fairways were Tifway 419 bermudagrass overseeded with perennial ryegrass, and the roughs were noshiba (Zoysia japonica). Here's the 15^th in November.

The course is at an elevation of 120 m. I downloaded the daily temperature data for the winter of 2000/2001 from the nearby JMA Sakahata weather station, which is also at 120 m. I think these temperatures are similar to those at the golf course.

From 29 November 2000 until 2 April 2001 there were 73 days with a low of 0°C or below. I think frost can form on the leaves even when the air temperature is above 0°C, but I'll stick with 73 days as an estimate of mornings with frozen or frosty turf.

In Japan, it is customary to do a two tee start, with tee times at 7 minute intervals, the golfers stopping for a meal at the clubhouse before starting their second nine. At Habu, there were about 3,000 rounds per month in the coldest months of that winter -- maybe more -- and 4,000 to 5,000 rounds per month in November, March, and April.

I wanted to implement frost delays, but it was impossible. The golfers wanted to play, and the owner wanted to accept their money. Let's say for each of those 73 days with frozen or frosted turf, we did not allow the golfers to play for 2 hours in the morning. That's 2 hours of tee times off 2 tees, on 7 minute intervals, which comes to 137 golfers. Let's say the green fee was 12,000 yen. And let's lose those customers for 73 days. 137 times 12,000 times 73 = 120,000,000 yen. That's about a million USD. The only days we had to close were when we could not clear the snow. But we were trying everything possible to clear it. That's some serious money.

So how about the grass? How much damage was there? On the tees and fairways, the damage was negligible. Of course traffic on slow-growing turf is going to beat it up a little bit. I did not notice that the traffic on frost or frozen ground added to that.

On the greens I was really worried. Courses with more staff would typically put covers out on the greens, at least over the area where the day's hole location would be. We did that as much as we could, but we could not cover all the greens, or even cover all of a single green, with the limited covers and staff that we had.

I've looked through old photos. This is the worst spot on the practice putting green in January. The putting green got a lot of traffic every morning. Pretty ugly.

This, in February, is the worst spot on the 11^th green, which was shaded until mid-morning in winter.

That was as bad as it got. By March, even though frosts were still happening, the grass filled in. The damage had not been nearly as bad as I'd expected.

In fact, the greens were cored on March 27. But winter still wasn't over.

By April, there wasn't a hint of damage from all the traffic. No grass was dead, any thin spots were gone, and the grass was growing like crazy.

I'm not sure there's a moral to this story, other than one must do what is in the best interest of the facility. In the case of Habu CC that winter, it was best to have customers playing the golf course.

I don't like turf diseases. If there is any fun in them, for me, it lies in only two things. First, is it a particularly well-named disease? Second, how awful are the symptoms?

I enjoy learning disease names and finding those that have the most interesting names. Nothing against brown patch and yellow patch, but those are pretty bland. Dollar spot is more interesting, and elephant's footprint even more so.

Then there are the symptoms. All turf diseases, if left unchecked, can make some hideous symptoms. In their standard form, however, I find some to be more hideous than others. Yellow patch, anthracnose, red thread -- often present, but sometimes only visible to those actually looking for symptoms. Compare to a disease like large patch, which in its standard manifestation is monstrous.

Using those criteria of interesting names and hideous symptoms, one of my favorite diseases is inu no ashiato -- dog's footprint. The name is interesting, and the symptoms are moderately hideous. I was glad to see this new article by Tomaso-Peterson et al. about Curvularia malina sp. nov. inciting a new disease of warm-season turfgrasses in the southeastern United States. From the introduction:

A foliar disease of these warm-season turfgrasses is often observed following prolonged or significant precipitation events such as tropical storms and hurricanes. The disease manifests as distinct chocolate brown to black spots (2–15 cm diam) that appear on Cynodon dactylon or Zoysia matrella putting greens, fairways, and tee boxes. Under high disease pressure the dark spots may coalesce to form large, irregular areas of blighted turfgrass.

"Is this the same as dog's footprint," I wondered?

A Curvularia leaf blight affecting Zoysia spp. in Japan, referred to as dog footprint, shares symptomology to that observed on C. dactylon and Z. matrella in the southeastern United States ... Based on these reports, our hypothesis is that the sterile fungus associated with Curvularia blight and causing similar symptoms in stands of C. dactylon and Z. matrella in the southeastern United States is a novel species of Curvularia.

The species was identified as Curvularia malina.

To date, C. dactylon and Z. matrella are the only golf course grasses from which C. malina has been isolated. Disease epidemics on Z. matrella appear to be more severe than on C. dactylon based on visual field observations. The disease is most prevalent in the spring and fall, which are normally characterized by moderate temperatures and ample precipitation. Symptoms may persist into the summer if prevailing environmental conditions remain favorable and the turfgrass experiences stress from intensive management practices.

So far so good. Dog's footprint is more severe on Z. matrella in Asia than on C. dactylon. However, in Asia the disease is most prevalent in summer, or in conditions characterized by warm temperatures and ample precipitation.

Based on the results of our research, C. malina induces disease symptoms in warm-season turfgrasses similar to those associated with Curvularia leaf blight.

It seems dog's footprint is caused by C. malina. Manilagrass (Zoysia matrella) can get lots of diseases, but in a tropical environment, this species is infected by few diseases, with the most common being dog's footprint.

Here is dog's footprint on manilagrass at Hilo in March.

This is at Okinawa in August.

This is at Manila in August.

This is at Shizuoka in July.

Those are pretty typical symptoms. And they are all on a monostand of one type of manilagrass.

I've noticed that some manilagrass varieties are often showing dog's footprint symptoms, and other varieties rarely do. I usually see this at two different locations in the same town. For example, lots of dog's footprint at site X, and then an hour later at site Y, a slightly different type of manilagrass has no dog's footprint.

Last July, I saw this at one location, on a golf course fairway with a mixed stand of different Z. matrella (korai) varieties and with some patches of C. dactylon.

On one variety of korai, lots of dog's footprint. On the Cynodon and other variety of korai, none.

This disease is ubiquitous on susceptible varieties in East and Southeast Asia. Finding varieties that are less susceptible seems quite possible.

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), 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
• Grass species and the two green system
• Golf course maintenance at Japan
• Not the usual everyday maintenance
• Golf in Japan, Mt. Fuji, and the two green system

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

When Eric Reasor came to Thailand in July, he brought along measuring tools to assess how golf balls roll across putting greens.

He visited 22 golf courses in 5 days. Here's a map with the locations visited marked as an orange ⊕.

The primary measurement he made was rolling balls using a customized Perfect Putter, so that all balls were launched on their roll at the same line and with the same pace.

Each ball was marked where it stopped.

Then the width and length of the dispersion area was recorded. Sometimes the balls dispersed a lot before they stopped.

On other rolls, or other greens, the dispersion was relatively small.

The purpose of the project is to study what factors influence the dispersion of the ball as it rolls across the green. Is it the grass species? Is it the mowing height? Do off-type grasses affect the dispersion? Is it something else? This is all part of his research about bermudagrass off-types. For an overview of this problem, see Reasor et al. on the genetic and phenotypic variability of interspecific hybrid bermudagrasses (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy) used on golf course putting greens.

As we traveled around central Thailand, we got to see all the major species used as turfgrass in this region. For more about that, see What grasses are growing on golf courses in Thailand? Here's a few notes about what we saw in July.

Seashore paspalum must be maintained with a relatively rapid growth rate in this climate. If paspalum is not kept growing, it will be overtaken by other grasses. Therefore, a lot of work is required to keep paspalum surfaces in a playable condition, and we saw verticutting on paspalum fairways to manage the organic matter.

There are lots of birds on Thailand golf courses. These are Asian openbill and a little egret.

I haven't identified this bird yet.

Bermuda greens and seashore paspalum fairways are pretty common around Bangkok.

Manilagrass (Zoysia matrella) is even more common. Let's call it ubiquitous. You can find it at the airport, along the expressways, in lawns, on golf courses, and on football fields and tennis courts.

This is bermuda on greens with the nuwan noi variety of manilagrass on fairways. The fairway would have been planted to bermudagrass, but over time the nuwan noi comes to dominate the sward.

In parks, palace lawns, and temples, one tends to find tropical carpetgrass (Axonopus compressus) under the trees and nuwan noi manilagrass in full sun. For more about the grasses on lawns, see this post about climate and this one about botanizing in Bangkok.

We were lucky with the weather for that time of year. With 22 golf courses visited, we got rained out zero times. Normal weather in July at Bangkok will have 155 mm of rain and 13 rainy days.

Hey @UTTurfWeeds, squeezing some data entry in isn't so bad after all pic.twitter.com/gD8pcD9Qr5

— Eric Reasor (@TurfBlade) July 15, 2016

We saw a bit of rain, but not enough to interfere with our work.

It was plenty warm. These are temperatures and heat indices at the time I collected data at 19 of the courses. It was only less than 30°C twice. What a great place for a tropical holiday! Or in this case, for 5 days of intensive data collection.