The month is January. The location is Bangkok, Thailand, 13° north of the equator. This is a golf course fairway. But all may not be as it seems. Can you see what is wrong, or at least what is unusual with the fairway in this picture?

Here is a look at the same fairway from another angle. Now do you see what is wrong with the picture?

These are not stripes on the fairway created by a mower. This is a bermudagrass (hybrid Cynodon) fairway with strips of seashore paspalum (Paspalum vaginatum) sodded in at the width of a fairway mower.

This course was in the middle of a conversion from bermudagrass fairways to seashore paspalum fairways, and the work was done in stages, to allow the course to remain open. Half of a fairway was sodded to seashore paspalum, and after that was well-established, the remaining strips of bermudagrass were replaced with seashore paspalum.

I'm changing the format of the #TurfMystery posts. Rather than ask for guesses, I'll just present the mystery and the answer together. I expect this will be just as interesting, and will avoid cluttered Twitter timelines.

Here's a mystery about green patterns in straight lines on greens in Iceland. This mystery is similar, at least in appearance, to these previous ones:

• The case of the subarctic stripes
• The tee with the solitary stripe

This is Iceland in early May. There was still snow on the mountains around Reykjavik.

The greens in question are primarily fine fescue. I noticed straight lines where turf was greener in one section and less green in another.

Was this caused by fertilizer?

Or was it a different variety of fescue, with a darker green color? Or perhaps the remnants of a pigment application from the autumn?

Maybe a nitrogen or iron application and only applied to a portion of the green?

The answer is not fertilizer, and not a greener variety of grass. What caused this was the application of dark topdressing sand.

Topdressing in the spring with dark sand is a great way to smooth out the green surface after a long winter, and it makes a big difference in the color of the grass due to the slight increase in temperature.

The areas in green received more sand. The areas that were less green had less sand applied, or were skipped, due to irregularities in the distribution pattern from the topdresser.

You'll see the difference in color from a closer look at a skip.

With such a short growing season, and cool temperatures, the practice of topdressing with black sand in the spring makes a lot of sense, and makes a big improvement in the turf. This is done on football pitches too.

For more turfgrass mysteries, see the archive here.

Engelke and Woods on zoysiagrass test plots in Oregon.

I was in Oregon last month, and I had the great opportunity to spend a few hours with Dr. Milt Engelke, studying and discussing grass in general, and Zoysia grasses specifically.

You might not expect it, but most cultivars of manilagrass (Zoysia matrella), and all cultivars of japanese lawngrass (Zoysia japonica), can survive in Oregon's Willamette Valley. In fact, the grasses I saw on my visit, in mid-October, looked really good.

The place, and the season, will give some hints about the correct solution to this mystery.

The location is Oregon's Willamette Valley.

The season is autumn, in this case, mid-October.

Manilagrass and japanese lawngrass growing in Oregon's Willamette Valley.

The grass species are primarily Zoysia japonica, Zoysia matrella, and some interspecific hybrids.

And this is the mystery.

The curious case of the Oregon Obtrusion. Can you identify the cause of this patch?

Dr. Engelke and I were looking at variety after variety, and then we came to a plot of Zoysia japonica with this patch on it. Keeping in mind the species, season, and location, can you solve this mystery? What is the cause of the patch on the zoysia?

Update: a closer look at this mysterious blemish.

I thought this might be mistaken for the beginning stages of large patch, considering it was the onset of cooler autumn temperatures and the species is Zoysia japonica. However, the uniformity of the patch and the clear circular shape were a strong indication that this was manmade.

Here are a series of answers.

@asianturfgrass it's too perfect of a circle for it to be pathogen. Has to be from an object covering turf for extended period

— Jason Goss (@gossturf) November 15, 2014

@asianturfgrass @terrydavio @theturfyoda base of a sprinkler?

— Jason Haines (@PenderSuper) November 15, 2014

@asianturfgrass Sprinkler base

— Tim Fleegel (@timfleegel) November 15, 2014

This is what that sprinkler looks like. The case makes it easy to drag the pipe across the field without damaging the impact sprinkler.

Some years ago, on a fine December day, I was at this beautiful golf course in southwestern China. The tees, fairways, and greens are creeping bentgrass. From the tee, I had the view above. But when I got to the fairway, I was surprised to look down and see this pattern.

In fact, there were a lot of cup cutter plugs, lined up one by one, on this fairway.

The mystery is this: why are there cup cutter marks in the fairway?

The correct answer was given in quick succession by @GreatManDan and then soon after by @gossturf.

@asianturfgrass Hydraulic oil would be my first option.

— DG (@GreatManDan) August 19, 2014

@asianturfgrass @gord_mckie repairs to a hydro leak?

— Jason Goss (@gossturf) August 19, 2014

What I found especially interesting was just how many plugs it took to make this repair. The diagonal across the fairway was about 175 yards in length. With each plug 4.25 inches in diameter, that would require 1482 individual plugs to make the repair. 

Late spring in the Yangtze River Delta. A time of glorious weather before the sultry summer. Tea in classical gardens. Flowering trees have bloomed, and are now in full leaf. On the golf course, grasses are growing a little more rapidly day by day.

That sets the scene for this mystery. A bermudagrass tee, in late spring, in the Yangtze River Delta of East China. In the previous 2 weeks, the lowest temperature was 10°C, and the highest was 31°C.

On the tee, a strip of green. Here is a look from another angle.

A closer look at the turf in the green stripe is here.

And this is what the turf looked like outside of the green stripe.

The mystery is this: what caused the green stripe on this tee? 

Congratulations to Jason Goss who got this one exactly correct:

@asianturfgrass they have a skip when they sprayed for transition back to warm season turf?

— Jason Goss (@gossturf) August 1, 2014

I think the key for this was recognizing the season and climate. With that type of climate, it is common to overseed bermudagrass tees. But one wants to ensure the bermudagrass can grow with no competition from perennial ryegrass for more than 100 days in the summer. That is necessary to keep healthy bermudagrass. Thus, on this high traffic tee, Monument herbicide (trifloxysulfuron) was used to remove the ryegrass, which will allow the bermudagrass to grow with no competition through late spring and all through the summer.

For more about this technique, see the Removing Overseeded Perennial Ryegrass from Bermudagrass Turf fact sheet from the University of Tennessee. 

Partial credit for a correct answer to @GreatManDan and @PenderSuper, who identified the herbicide skip and ryegrass involvement.

Thanks to everyone who sent their answers. For other turfgrass mysteries, click here.

This mystery comes from the Westman Islands. For an overview of turfgrass in Iceland, see this report and these photos.

When I visited the Westman Islands GC, most greens looked as above. The grass was healthy at the end of summer. But there were a couple greens that had some bare areas, as shown below.

A closer look at the bare areas revealed this appearance.

The mystery is this: what caused the grass to fail in some areas? I wouldn't wish this pernicious problem on anyone.

The answer is nematodes, and Dr. Brett Morris identified exactly what has happened:

@asianturfgrass first thought was nematodes weakening the Poa

— Brett Morris (@brettmorris73) May 7, 2014

 Partial credit for a right answer goes to Nadeem Zreikat from Campbell Chemicals, who guessed disease or nematodes, which I didn't think was specific enough. If you click on the photo above, you will see the bare area has Festuca rubra growing in it but not Poa annua, although one can see a few plants of Poa annua in the surrounding areas. 

In looking at the root system of the Poa annua, one can find root galls caused by Subanguina radicicola.

The nematode damage to the root system of the Poa annua makes it more susceptible to stress, especially when the grass is maintained with low nitrogen applications to favor the desired Festuca rubra.

Related articles

Turfgrass Mystery: how was this bunker revetted?

Turfgrass Mystery: what happened to this green?

Turfgrass Mystery: the case of the subarctic stripes

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

For this mystery, I take a slightly different tack, and consider golf course design rather than turfgrass specifically. Each of the three courses shown in this post were designed by the same architect. The hole pictured above is a par 3 on a course in Hokkaido. The hole pictured immediately below is a par 4 on a course in Osaka.

I've noticed a dramatic and distinctive style to the courses designed by this architect. The courses may not be easy to maintain, and may not be easy to play, but they certainly will be memorable, and are some of the most extensively-mounded courses I've seen in Japan.

The final clue is this view across a course by the same architect in Okayama.

This mystery is a simple one. Can you identify the architect of these courses? I expect readers familiar with Japanese golf will know this right away. For those less familiar with golf in Japan, and wanting to do some research on this, I suggest the informative Golf in Japan site.

This was answered correctly, and quickly, by Andrew McDaniel, golf course superintendent at Keya GC. 

@asianturfgrass @tgc_daiiwa @akicic @alban3074 @fc3s_13b @ManzanSimizu 加藤俊輔 です！

— Andrew McDaniel (@drumcturf) March 14, 2014

 These courses were all designed by Kato Shunsuke. And the photos, from top to bottom, are Hokkaido GC, Hanna CC, and JFE Setonaikai GC. Kato's distinctive design style can be seen at many courses in Japan.

Below I've posted one more photo, this of Kato's Tojo GC in Hyogo prefecture. 

This one, I think, will be relatively straightforward. Last week I was at Mauritius. I spoke at a seminar, and I also had a chance to explore the island and to study the grasses growing near the ocean.

I saw this grass growing at nearly every beach, on all sides of the island. It clearly has a high salt tolerance, because at high tide, the ocean water completely inundated some of the plants. I didn't notice salt causing any damage to the grass.

This grass was also observed slightly up from the water line, where the sand and grass were not inundated daily.

It was especially impressive to see this grass, at high tide, completely covered by ocean water.

The mystery I would like to solve is this one: what species is this grass?

The answer to this mystery is Sporobolus virginicus, correctly solved by Mark Field:

@asianturfgrass Sporobolus virginicus?

— Mark Field (@cricketgman) December 24, 2013

There are a number of interesting characteristics of this grass that set it apart from two other common grasses (Paspalum vaginatum and Zoysia matrella) found in tropical coastal areas.

• S. virginicus is adapted to low rainfall and is very drought tolerant with low water requirements
• S. virginicus is believed to be pest-free
• Z. matrella is less widespread and one doesn't find it so much growing in sand; Z. matrella is found close to sea level and in saline conditions but usually is anchored onto rocks or other stable surfaces
• P. vaginatum will not tolerate drought and prefers moist to saturated sites

This fact sheet from the USDA provides details on S. virginicus.

@asianturfgrass @cricketgman plenty around the Coast of Australia, here's some more I saw yesterday growing well pic.twitter.com/cfqDAsOwp0

— Brett Morris (@brettmorris73) December 24, 2013

Dr. Brett Morris shared the above photo of S. virginicus growing in it's typical environment, right on the sand near the high tide line, where it will sometimes be inundated with saline water, and sometimes be exposed to extended periods of drought stress.

The leaves of S. virginicus and P. vaginatum appear very similar, and the best way to tell these grasses apart is to find plants with spikelets. There are profound differences in spikelet morphology between the two species. 

At right is S. virginicus found on the beach at Bel Ombre, Mauritius. Note the spiciform (spikelike) panicle. P. vaginatum, however, has paired racemes, as shown below.

This mystery comes from a putting green in Spain. The grass is Penn A-4 creeping bentgrass. One can see at the corner of the green a mark from the triplex mower as it makes the cleanup pass. And diagonally across the green, there is this line of damaged grass. Here is a closer look at the mysterious line.

Can you identify the cause of this line on the green?

Greg Austin was the first to identify this as an ant trail across the green:

@asianturfgrass if animal damage is close, my next guess would be damage from insects. Possibly ant damage. From a trail?

— Greg Austin (@bcgolfsuper) December 16, 2013

Steve Agin also correctly identified the cause of this line. Getting closer to ground level on the green, one can see that this is an ant trail. Thanks to David Bataller for sending the photos for this turfgrass mystery.

This ant problem is similar to this turfgrass mystery that turned out to be termite damage on a bermudagrass (Cynodon) putting green. Click here to read all the previous turfgrass mysteries.

In mid-July, I visited a course in West Japan as it was being prepared for an upcoming professional tournament. The manilagrass (Zoysia matrella) greens, known as korai in Japan, were in excellent condition, whether they were heavily shaded (above) or in full sun (below). Manilagrass is known for its improved tolerance of low light compared to bermudagrass.

 At the edge of some greens, near the point where the korai green and collar merged into the noshiba (Zoysia japonica) rough, I noticed this surprising blemish. 

Looking closer at these spots, the turf looked like this:

The spots seemed to be where the korai and noshiba were mixing at the edge of the green, and they were equally found in sunny and in shaded areas. What was the cause of these spots?

This mystery was solved by three people in quick succession. Thank you all for helping to solve this and sharing your knowledge. First was Steve Link:

@asianturfgrass #turfmystery Looks a little like hot exhaust from a vehicle paused to remove flag or obstruction.

— Steve Link (@Super__Link) December 9, 2013

Then Gerard McEvoy identified the cause:

@asianturfgrass is the turf mystery from an exhaust of a machine left running in the same place

— Gerard McEvoy (@Prograss1) December 9, 2013

And then Jon Scott identified the cause and the exact piece of turf machinery that caused these greenside spots:

@asianturfgrass exhaust burn from a greens sprayer? I have seen this several times over the years on different golf courses.

— Jon Scott (@jonscott49) December 9, 2013

Click here to read all the previous turfgrass mysteries.