Top 25 tweets of the Ryder Cup*

There's an asterisk on this, because I limit this to 4,098 unique tweets returned by a search for ct_turf from September 22 to October 4. From those, I selected the 25 with the highest favorite count. Note that the favorite count was at the time of the search, which was multiple times from Sep 29 to Oct 4. Thus, the favorites on the tweets may be quite different now from the time of the search.

As an example, Jeff Johnson's "tweet of the year" about amazing surfaces didn't make my top 25 because that tweet was saved just a couple hours after it had been posted, when it hadn't yet reached the 103 favorites that I see at the time of this writing.

From the 4,098 tweets returned by a search for ct_turf, I wanted to find those that had the most favorites. That's an easy assessment of which tweets were the most popular.

First, I checked the favorite count on all the tweets. I had a set of tweets from the evening of September 22 until midday on October 4.


Then I found the top 25 in terms of how many favorites they had at the time the search was made.


For easy viewing, I put all 25 of those tweets together here:

Monthly Turfgrass Roundup: September 2016

In this month’s roundup: fertilizer, roots, golf in Japan, identifying a turf disease, the Ryder Cup, putting green performance, and much more.

What's the probability of a positive response to fertilizer application?

Sue Crawford reports on a #MLSN trial green:

Golf with two greens on each hole.

Lawn fertilizer calculator from University of Missouri.

Eric Reasor shared this tip on scouting for offtype grasses:

Fast release fertilizer, burn, and root growth.

Andrew McDaniel shared photos of pre-Ryder Cup preparations:

Measuring ball roll dispersion on putting greens.

Andrew Kniss on the environmental impact quotient (EIQ). It's not better than nothing.

Thailand putting green performance.

Paul Jansen on the Japanese golf experience.

A new Shiny app with the temperature and sunshine combination for 11 cities in Japan.

Chris Tritabaugh from the 1st tee at Hazeltine:

The turfgrass disease called dog's footprint.

Documenting more preparations for the Ryder Cup:

For more about turfgrass management, browse articles available for download on the ATC Turfgrass Information page, subscribe to this blog by e-mail or with an RSS reader - I use Feedly, or follow asianturfgrass on Twitter. Link and article roundups from previous months are here.

Applying the grammar of greenkeeping

Over the past two weeks, I've had multiple conversations about the way I think of turfgrass management. It all starts with a definition of greenkeeping as managing the growth rate of the grass. I wrote about this in A Short Grammar of Greenkeeping. You can get your copy here.

Application of the grammar allows for easy communication among turfgrass managers about the work they are doing. I'll use the creeping bentgrass greens at Hazeltine National GC as an example. Volunteers from near and far were at Hazeltine during the Ryder Cup.

Let's say that I was from Madrid, or San Francisco, or Sydney, and I wanted to get green conditions that were more like those at Hazeltine. One of the ways I would try to do that would be to apply a similar quantity of nitrogen. But how to compare locations?

I would use the temperature-based growth potential (GP). For Minneapolis, the GP looks like this.


If I set the maximum monthly N at 3 g/m2, and multiply by the GP, I get a maximum annual N of 13.3 g/m2 for that location (Minneapolis). Now I'll make up a number, because I don't know exactly what it is, but let's say the actual quantity of N applied at Hazeltine was 9 g/m2.

I'll use the log percentage (L%) difference for consistency. The L% is the natural logarithm of the ratio of two numbers, multiplied by 100:

If 9 g N were applied at Hazeltine, and the value calculated using GP as described above is 13.3 g, that is a 39 L% reduction.

If I want to apply proportionally the same amount of N at another location, I can calculate the GP amount, which I'll call a standard value, and then take a 39 L% reduction.


The standard using these calculations comes to 16.7 g at Madrid, 20.1 at San Francisco, and 28.9 at Sydney. Knowing that there was a 39 L% reduction at Hazeltine, my starting point for Madrid, after applying the same reduction, would be 11.3 g N/m2. At San Francisco, the N would go from the standard calculation of 20.1 down to 13.6 g, and at Sydney the 39 L% reduction takes N from 28.9 to 19.6.

This grammar facilitates the rapid sharing of relative inputs used to produce turf surfaces all over the world. Let's say we know there are amazing bentgrass greens in Sydney with N inputs of 10 g/m2/year. A corresponding quantity of N in Minneapolis would be 4.6 g.

This same approach can be applied for the quantity of water supplied in comparison to evapotranspiration (ET), to frequency of mowing, to evaluation of the growth rate, to assessment of the photosynthetic light, and so on. I find this approach quite useful in rapid implementation of maintenance practices that work well at location A, applied to location B. One then has a site specific starting point that can be further adjusted at location B, based on turfgrass response at that location.

The relationships between golf and health, with multifunctional golf facilities thrown in just for fun

Golf and health

Yesterday I saw the new paper by Murray et al. in the British Journal of Sports Medicine on The relationships between golf and health: a scoping review. The reviewers identified 301 studies on this topic that met their search criteria, and then they summarized the results in terms of:

  • participation
  • golf and physical activity
  • golf and longevity
  • golf and physical health
  • cardiovascular system
  • respiratory system
  • metabolic health
  • cancer risk
  • musculoskeletal health
  • golf and injury
  • golf and mental health/wellness
  • mental health
  • mental wellness

It's a comprehensive review, and if you are interested in this topic, I suggest you read the paper. From the golf and physical activity section, here's the calorie burn and walking distance:

Studies assessing calorie expenditure during golf typically classify golf as a moderate intensity physical activity with energy expenditure of 3.3—8.15 kcal/min, 264—450 kcal/hour, and a total energy expenditure of 531—2467 kcal/18 holes. Golfers walking 18 holes take between 11,245 and 16,667 steps, walking 4—8 miles, while those playing and riding a golf cart accrue 6280 steps or just under 4 miles.

This ties in well with something I've written about before, which is golf and health and multifunctional facilities. In the words of Don Mahaffey, "golf is good for you" but this aspect of golf is often overlooked.

See these posts for more from Don Mahaffey, and from info about STERF's research into multifunctional golf facilities:

A few examples of multifunctional facilities


Weddings and banquets, of course, are common at many facilities. This is a chapel at Club de Golf Escorpión in Valencia.


Use of a practice tee for sports training, at Escorpión.


A football field at El Saler, just to the right of the 8th and 9th holes. This has been used by the Spanish national team and by Valencia CF, among many others.


Birdwatching is a common activity at El Saler, and this sign near the clubhouse shows many of the species one can find in this area.


Many golf facilities have trees or hedges with fruits or nuts. At Golf Costa Brava, the cork oaks are harvested.


Walking, hiking, or biking the Cami Ral will take one right through PGA Catalunya.


Hiking paths at Domaine de Falgos in the Pyrénées start at the golf clubhouse.


The driving range fairway at Domaine de Falgos doubles as a rugby field.


A Ryder Cup miscellany, in charts

I was recently at Hazeltine National Golf Club for the Ryder Cup. When I arrived, I was informed that it had been extraordinarily rainy since early to mid-August. I had a chance to observe the rain myself as well. I wondered just how extraordinary the rain was, so I looked it up.


You can see all the charts I made in this Flickr album.

Ryder Cup 2016 charts

Another thing I looked at was when, who, and about what were people communicating with Chris Tritabaugh, the golf course superintendent at Hazeltine National Golf Club.


These are the words used most often during the week in tweets mentioning Chris's Twitter account.


This shows the discussion about the @ct_turf account on Twitter for the week. There are a number of hubs in the discussion.


Zooming in to just one hour on Saturday morning, one can see accounts grouped into conversations based on who was communicating at that time.


I even made a word cloud, these for the conversation on Saturday, 1 October.


All 33 charts are in this album if you would like to see more.

Dog's footprint and grass susceptibility to this disease

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.

"Anyone who's played golf in Japan will know that many clubs have two greens on each hole"

Selection_101Fred 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:

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.

Shiny app shows the temperature and sunshine combination for 11 cities in Japan


I made a Shiny app with climatological normals data from the Japan Meteorological Agency to show the combination of sunshine and temperature at 11 locations.

@naturalgolf_D asked "What kind of situation is Japan?" With these data, I think it is interesting to compare different locations of interest, and a Shiny app is an easy way to do that.

Six more Shiny apps from ATC are here.

Thailand putting green performance in July: a summary


While Eric Reasor was collecting the data on ball roll dispersion in Thailand -- read yesterday's post for more about that -- I collected data on the the same greens. The data summary shown here are the data I collected from 19 greens on 19 different courses. The grasses on these greens included various bermudagrass varieties, seashore paspalum, and manilagrass.

I took 3 stimpmeter readings per green, measured 9 locations per green with a 500 g Clegg soil impact tester, and used a TDR-300 with 7.5 cm rods to measure soil water content at those same 9 locations. I also made some measurements of soil temperature, surface temperature, and air temperature.

I showed the distribution of air temperature (median was 31.8°C) and heat index (median was 38.9°C) in a previous post.

Here's the summary of soil and surface temperature from these greens.



Putting greens in Thailand tend to be relatively soft, and the measurements in July were consistent with previous measurements.


This is the distribution of soil water content.


This is the distribution of green speed.


I measured the speed on each green in 3 different locations. With that, I get some idea not only of the green speed, but also about the variation in green speed. I express the variation in green speed within a green as the coefficient of variation (cv), which is the standard deviation of the measurements on a green divided by the mean of the measurements on a green.

Then I compared the distribution of cv for the 19 greens measured in Thailand with the cv for 26 greens measured during the recent KBC Augusta tournament in Japan. Under tournament conditions, there was slightly less variation in green speed. But many of the greens in Thailand had variation the same as measured during a tournament.


For more summaries of putting green measurements, and of measurements from greens in Thailand, see this post on playing with numbers. There are links to handouts and other data sources there. Or look at the charts in these slides:

Bangkok is a long way from Knoxville


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.

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.