Turfgrass Mystery

Turfgrass Mystery: the case of the subarctic stripes

Last month I went to Iceland, visiting 11 golf courses and speaking with the Icelandic Green and Groundskeepers Association. If you would like to see more, I put together this set of amazing photos of those grasses and courses. Those links provide good background information on the climate, grass types, and other turfgrass management issues in Iceland.

This mystery is at a golf course near Reykjavik. Have you ever seen turf look like this? There are stripes going across the green. I had never seen anything look quite like this.


Here is a closer look.


This striping was not evident on other greens on the course. I saw it only on this practice putting green near the clubhouse.

Can you solve the case of these subarctic stripes? This was quickly identified as lines related to sod, and then to be different varieties of grass (in this case, fine fescues), causing the stripes.

2_fescueCongratulations to Tom Margetts for solving this mystery in record time.

A close look at the turf from the different areas shows it to be primarily fine fescue, a mixture of slender creeping red fescue and chewings fescue, with the color differences caused by blends of different varieties within those species, producing swards of different density and color. One can see a few plants of Poa annua in there as well.

Thanks to everyone who helped to solve this mystery. To see all the turfgrass mysteries from this blog, starting with this one, click the Turfgrass Mystery tag below.

Turfgrass Mystery on the Putting Green


This is a good one. A friend sent me these photos and asked if I could identify what had caused the yellowing seen in the photo above, and in a closer view below. I couldn't solve it at first, but once it was explained to me, the symptoms made perfect sense.


Here is a bit of contextual information that may help in solving the mystery. These symptoms appeared on a korai (Zoysia matrella) putting green maintained at a mowing height of about 3 mm in Japan in early August. Can you identify what has happened here?

This one proved difficult to solve, with answers coming in speculating that it was caused by: surfactant or herbicide spilling from a leaky bucket; scalping caused by too much fertilizer or sand or grain or aerification; crop circle caused by mythical rabbits; disease; fireworks; bug spray; and more.

The correct answer is that this korai green had a few small patches of Miniverde utlradwarf bermudagrass in it. The greenkeeping staff removed the Miniverde by plugs, replacing with korai, but somehow did not remove all the Miniverde. Because of the different growth habit between korai (very upright) and bermudagrass (more creeping and stoloniferous), when the greens were verticut, the korai remained green, while almost all the green leaf material of the Miniverde was cut off.

Dr. Brett Morris from Australia and Billy Aylmer from Ireland were the closest in identifying the cause of this mystery.

One of the implications of this differential response to verticutting is that korai greens grown in that climate may require substantially less frequent verticutting than ultradwarf bermudagrass. The Miniverde would not have looked like this had the greens been verticut more frequently.

Turfgrass Mystery: what happened to this green?


This is a MiniVerde ultradwarf bermudagrass green in the western part of Japan.

These photos were taken on 1 and 2 October. For a closer look at the grass, click on the image below:


At this location, the average air temperature for the previous three months had been 27.7°C in July, 30.3°C in August, and 26.3°C in September. Those are almost optimal temperatures for the growth of ultradwarf bermudagrass. It rained a lot in July, 454 mm, and then August and September saw 70 and 139 mm of rain, respectively.

In the worst area of the green, it looked like this:


However, it would seem that the weather in the preceding three months had been almost ideal for the growth of ultradwarf bermudagrass. 

The mystery is, what happened to make the green look like this? 

Here is one more photo. In the foreground is the mysterious MiniVerde green. In the background is a manilagrass (Zoysia matrella, called korai in Japan) green, that seems to be fine by comparison.

This was a tough mystery to solve, with many guesses, ranging from disease, to localized dry spot, to salt damage, to scald from hot topdressing sand, and many more. This damage was actually caused by application of the fungicide tebuconazole. I don't usually expect to see fungicides having this effect on grass, so I found this a difficult mystery to solve myself. Here is the correct answer.

Thanks to everyone who helped to solve this. I have seen damage, sometimes severe, on ultradwarf bermudagrass greens in multiple countries in Asia after they have been sprayed with DMI fungicides (such as propiconazole or tebuconazole) at the label rate. Difenoconazole is supposed to be safer. For more information about DMI fungicides and bermudagrass greens, see this article by Dr. Monica Elliot: Bermudagrasses vulnerable to injury from some DMI fungicides.

In this situation, the tebuconazole damage was compounded by uneven application of the product. In the photos above, one can see various patterns of heavy or light application. The application method was similar to below, using a tanksha sprayer and applying the product with a hand wand.

I should give some partial credit to these responses also, for correctly identifying that the application method applied a product unevenly.


Turfgrass Mystery: why is there a ring of green grass around the collar?

green grass in June near Tokyo

This turfgrass mystery is illustrative of a couple of interesting points. These will be explained once the answer is given. This photo was taken in early June, 2001, at a golf course in Japan, near Tokyo. At right is the collar of the green, mown at 12 mm (1/2 inch). In the center is a band or ring of particularly green grass, and at left the grass is more yellow. At the right side of the photo, the grass condition is basically uniform, but at left there is the green grass and the yellow grass.

Can you identify what has caused this green band of grass, and why the grass at the left is yellow?

This was solved without too much trouble.

It was correctly pointed out that this must have something to do with fertilizer, with the green ring of grass responding to fertilizer that had also been applied to the green. But that is not all there is to it. 

The overlap of fertilizer didn't stop right where the grass turns from green to yellow. The yellow and shorter grass at left is japanese lawngrass (Zoysia japonica), and the grass at right is primarily perennial ryegrass (Lolium perenne). The fertilizer overlap extended into the zoysia. Because of the temperatures during this season, the ryegrass could use the nitrogen, and did, while the temperatures were too cool for the zoysia to make much use of the extra nitrogen.

At this interface between warm-season (Zoysia japonica) and cool-season grass (Lolium perenne), one grass was able to use the applied nitrogen, and the other could not. For the three weeks leading up to the date of the photo, I have calculated the daily growth potential, based on the actual temperature in 2001. This plot shows just how good the weather was for the ryegrass, and how relatively poor the weather was for the zoysia.

In fact, the average cool-season (C3) growth potential in this span was 0.96. For the warm-season (C4) grass, the growth potential never got above 0.5, not even for 1 day, and the average growth potential was 0.29. For more information, see Explaining the Turfgrass Growth Potential.

Turfgrass Mystery at the sod farm


I recently visited a sod farm in Tennessee and saw these sinkholes in a field of tall fescue (Festuca arundinacea). After the sod cutter went across the field and the individual pieces of sod were lifted, it became apparent that there was some tall fescue growing below grade.

This machine, shown here harvesting a field of hybrid bermudagrass (Cynodon), was used to cut the field of tall fescue.

I asked, "Can you identify what has caused this phenomenon?" There were many responses before the correct answer was given.

Some were close to the answer -- guesses of elephant tracks, water buffalo or horse footprints, groundhog holes, bird scrapings, bear footprints, misaligned aerification holes, fox damage, hail marks, repair plug removal, holes created by worms or insects, or perhaps rock removal from the field. The correct answer was that a cow or cows escaped into this field just after planting, pressing the tall fescue seed down and it remained there, growing in the footprints, until harvesting when those below-grade footprints appeared. Correct answer from Jason Haines below:

My advice is to keep large animals off of sod production fields, although the cows on this manilagrass (Zoysia matrella) sod farm in northern Vietnam, shown below, didn't cause any problems once the turf was established.


Turfgrass Mystery: where can we find this beautiful grass?


This might be an easy one. The picture above is manilagrass (Zoysia matrella) and was taken in December 2009. If you've followed this blog, you will know that I am a big fan of manilagrass in East and Southeast Asia, as this native grass produces a fine turf with fewer problems than other grasses in this part of the world. The grass in this picture is perhaps the best example and the best-maintained large sward of manilagrass in Southeast Asia.

The simple turfgrass mystery was ... where was this photo taken? This turf is at the Manila American Cemetery.

The location was identified correctly:

The turf here is not only some of the best manilagrass in Southeast Asia, it may be the best large sward of turf in all of Asia. The fine lawns at the Manila America Cemetery are spread over more than 31 hectares and are usually mown at less than 20 mm. 

The grass here should be studied by whoever works in turfgrass management in Asia. For more than 50 years, the manilagrass has produced an excellent surface here, and the native manilagrass has many advantages over the Cynodon and Paspalum species that are often planted in Southeast Asia. Mnl-am-cemetery1

Turfgrass Mystery: a spotted seashore paspalum green


This is a seashore paspalum putting green in Hawaii. You can click the photo to view it at a larger size. Can you identify the cause of the spots on the green? 

This looks a lot like dollar spot, which is common on seashore paspalum, and many people guessed that. The correct answer, however, was salt used as a herbicide to control Eleusine indica. Three people got the answer right, all at about the same time:

I described this in a post a few years ago, At Hawaii ... More About Salt Applications to Seashore Paspalum. And this is what the salt applications do to Eleusine indica without damaging the seashore paspalum.


Turfgrass Mystery: can you identify the grass on this putting green?


This is a warm-season (C4) grass that performs well on putting greens in the tropics. Click the image above to see a larger view. The photo was taken on a putting green in Asia just 1° north of the equator.

I've seen it as a fairway or lawn grass, but as a putting green turf, I've only seen this use in Asia. It seems to perform best with relatively minimal maintenance and does well in areas with relatively high cloud cover and rainfall (it is not a Cynodon species) where bermudagrass struggles. It also grows well in some relatively cool, because of high altitude, areas near the equator. It should probably be used on more golf courses.

Can you identify this grass? 

Here's another photo. It looks almost like creeping bentgrass, doesn't it?


The answer is serangoon grass (Digitaria didactyla), also known as blue couch.

After a discussion on Twitter with many people guessing that this was Zoysia matrella or Zoysia pacifica, due to it performing so well in areas with lots of cloud cover, the correct answer was provided at almost the same time by HK Golfer Magazine,

and then by Albert Bancroft.

We find serangoon grass greens in Singapore, and in Malaysia, and they generally perform very well. I've also seen this grass thriving on the greens of the famous Nuwara Eliya Golf Club (below) high in the mountains of Sri Lanka, at Bangalore, and at the organically-managed Kodaikanal Golf Club in Tamil Nadu.


A Turfgrass Mystery on Seashore Paspalum in Tamil Nadu


Last week I visited a golf course in Southern India and saw these symptoms on seashore paspalum turf. The general symptoms are shown above, and a close-up of a single patch is shown below. 

Can you identify the cause of these patches? 


This one was quickly solved by three people. Did you have the same answer?

Elephant_crossing_zone_tamil_naduThat, of course, is the correct answer, as this course, right up against the Western Ghats, is visited frequently by elephants. 

If we take an even closer look at one of the elephant footprints, we can see that the patch seems to include some dried mud that remains on the leaf, along with some bruising from the weight of the elephant.

These footprints should not be confused with the autumnal disease of Zoysia japonica in Japan, caused by Rhizoctonia cerealis, and known by the common name of elephant's footprint.


Hopefully this information will help you to identify elephant footprints on your turf the next time they occur, and you will easily be able to distinguish the real elephant's footprint from the one caused by R. cerealis.

Turfgrass Mystery: what is causing the splotchy dew pattern on this fairway?

Quiz-201209 1
Ok, here is a relatively easy one. What is causing the splotchy dew pattern on this warm-season fairway? Click the image to see a larger view. Bonus question: what country is this golf course in?

Thanks to everyone who responded. There were guesses of something to do with soil moisture (that was my first guess on this also!) and something to do with the trees, neither of which are correct, and a flurry of answers related to it being two different grass species with a difference in the way the leaves hold the dew.

That, of course, is the correct answer, and @GreatManDan gets the credit for identifying bermudagrass (Cynodon dactylon) as the grass holding the dew, and zoysiagrass as the grass not holding as much dew. For the bonus question, @campbellturf correctly identified the country as Japan. In the second picture, the cart path tracks, used with remote-controlled golf carts at so many courses in Japan, gives the country away.

Quiz-201209 2

This course was originally planted to Zoysia japonica in the rough and Zoysia matrella on the tees and fairways. In central and western Japan, when a little bit of bermudagrass finds its way onto the course, it tends to spread and spread, and these photos show just how much it has spread, as evidenced by the morning dew patterns.