Sun, Ice, and Climatological Normals

Since my last post I've been to England and the UAE, Philippines, Vietnam, Thailand, and Japan. I've seen most grass types but not many diseases; a bit of fairy ring, some dollar spot, slime mold, and Curvularia. What I have seen is a lot of variability in the weather, and especially in Asia I have seen the typical cloud cover, rain, and associated low sunshine hours that are so widespread during these months of the year.

When we look at the factors that influence turfgrass growth, we can identify nutrient status, water status, temperature, and light as being the primary factors. But with drainage, supplemental irrigation, and fertilization, turfgrass managers are able to control the nutrient and water factors, at least in theory, which leaves just temperature and light as the factors influencing growth. I find it useful to look at the climatological normal data, as seen in the chart below for August, or in this interactive chart with data for the entire year, to evaluate how the temperature and sunlight may influence turfgrass growth at a particular location.

Zoysiagrass outperforms seashore paspalum and bermudagrass in low-light conditions, both in the research setting and in the field throughout Asia. In tropical Southeast Asia, where the temperature remains relatively constant throughout the year at an optimum level for warm-season turfgrass growth, it is the light factor that controls the growth of the grass. Zoysia is especially well-suited to that environment.

An environment that creeping bentgrass is not well-suited to is the summer in Japan; a place like Osaka (where bentgrass is almost universally used on putting greens) is hotter during August than cities such as Singapore, Honolulu, and New Orleans. I've been making some measurements of the changes that take place in surface temperature and soil temperature when ice or ice water are applied to creeping bentgrass greens in Japan. I've been surprised at the persistence in soil cooling from the melted ice, although clouds and rain have moved in this week and I've been unable to continue these experiments.

Botrytis, Dog's Footprint, and Hot July Weather

Megan informed us last year that there are some edible (or drinkable) plant pathogens. I saw a few turfgrass pathogens during an early winter visit to Australia last month — some dollar spot on seashore paspalum, leaf spots on Cynodon, pink snow mold on creeping bentgrass, and the mysterious and as yet unidentified fairway patch (black fungus) disease affecting Cynodon fairways at Sydney. But my favorite disease was a drinkable one in the Barossa Valley of South Australia: the Peter Lehmann 2009 Botrytis Semillon.

Ten summers ago, before I went to grad school, I was a golf course superintendent in Japan (and during the three summers before that I was a superintendent in Shanghai). We all looked much younger then, but one thing that hasn't changed is that China and Japan remain really difficult places to grow creeping bentgrass. I'm spending most of this summer at Japan to observe golf course maintenance practices and grass performance, to collect some data, and to remember what it is like to be a golf course superintendent.

In the past week I saw some moss (above) and slime mold and dollar spot on creeping bentgrass, large patch on Zoysia japonica roughs, and the splendidly-named "dog's footprint" disease (Curvularia, below) on Zoysia matrella fairways.

Why do I say that China and Japan are really difficult places to grow creeping bentgrass? Have a look at this chart of world cities plotted by average weather data:

As we look at the average data for July, Tokyo is a little cooler than Atlanta, Osaka and Shanghai are both warmer than Atlanta, and there is less sunshine in the Asian cities than there is at Atlanta. At Atlanta you may find creeping bentgrass greens or ultradwarf bermudagrass greens. But at Shanghai, Tokyo, or Osaka, more than 95% of the greens are creeping bentgrass. It gets worse in August and September, when Shanghai, Tokyo, and Osaka all have higher average temperatures and less sunshine than Atlanta. "Change to ultradwarf bermudagrass, then, if it is so hot!", you might say, but in winter it is colder in the Asian cities than it is at Atlanta, and the annual sunshine hours in Shanghai, Tokyo, and Osaka are about 70% of what they would be at Atlanta. There is no easy answer. Here are the temperature readings I saw just before I left Japan yesterday. I'll be spending this coming week on a much cooler continent.

Spring dead spot of zoysiagrass

Spring dead spot of bermudagrass

After a cold winter throughout much of the Southeast, damage from spring dead spot is particularly severe on bermudagrass. Scenes like this one are all too common when visiting golf courses in North Carolina right now.

We're also seeing an unusually high number of spring dead spot outbreaks on zoysiagrasses across the southeastern US. Samples, photos, and reports of spring dead spot on zoysiagrass fairways, tees, lawns, and landscapes have been rolling in all spring.

Spring dead spot of zoysiagrass?

Yes, this is not a new thing. Spring dead spot was first documented in zoysiagrass by Green et al. in 1993 as part of the zoysia patch complex, which turned out to be mostly large patch and a little bit of spring dead spot. The Color Atlas of Turfgrass Diseases by Tani and Beard also lists spring dead spot as a disease of zoysiagrasses in Japan. 

In North Carolina, we've seen spring dead spot on zoysiagrass every year since 2002 and documented that it is caused by Ophiosphaerella korrae, the same species that infects bermudagrass in this part of the country.

Spring dead spot of 'El Toro' zoysiagrass

Overall, zoysiagrass seems to be more resistant or tolerant to spring dead spot compared to bermudagrass. The patches are typically smaller and not as widespread. Given the superior cold tolerance of zoysiagrass, this makes sense. The problem is that zoysiagrass is even slower to recover from spring dead spot than bermudagrass. Although the symptoms may not be as severe, they can linger for extended periods of time.

Not all zoysiagrass varieties seem to be susceptible to spring dead spot. In Kansas the disease was observed on 'Meyer'. In North Carolina, most cases have been observed on Zoysia japonica varieties like 'El Toro' and 'Empire'. 

Spring dead spot of 'Diamond' zoysiagrass

This year is a little different in that we're seeing spring dead spot on more varieties. Most notably, we've confirmed the disease on golf course fairways and tees established with the Zoysia matrella cultivar 'Diamond'. To our knowledge this is the first confirmation of spring dead spot occurring on Zoyisa matrella.

Spring dead spot management on zoysiagrass is identical to that on bermudagrass. We've seen very good results from preventive application of fenarimol (Rubigan) in the fall. Regular cultivation during the summer also helps to reduce spring dead spot development and speeds up the recovery process. We're continuing to research the effects of nitrogen sources and other fertilization practices on spring dead spot development, but I don't have time to open that can of worms this week. Stay tuned for details on that in next week's post!

Why They Call it the Transition Zone

Spring dead spot of bermudagrass

As the old joke goes, "In the transition zone, we can grow all of the turfgrasses, we just can't grow any of them well".

The last year has been an excellent demonstration of this fact. Spring 2010 brought major problems with winter-kill in the warm-season grasses across much of the southeast. Everyone will remember the summer of 2010 as the year when record heat caused widespread failure of creeping bentgrass putting greens. 

Large patch of bermudagrass

The spring of 2011 hasn't been much kinder. Spring dead spot is particularly severe on bermudagrass this spring, and I've heard several reports of control failures from preventive fungicide applications. We've seen an unusual number of cases of spring dead spot on zoysiagrass as well (more on that next week).

Large patch (aka zoysia patch, aka brown patch, aka large brown patch....did I miss any? Seriously, can't we all just call it large patch?) is raging on all of the warm-season grasses as well. This spring is the first time I've seen large patch cause significant damage to bermudagrass in the Raleigh area. Zoysiagrass, St. Augustinegrass, and centipedegrass are affected very severely as well.

Many people struggle with these diseases of warm-season grasses because they have to be treated long before the symptoms express themselves. It is easy to forget about spring dead spot and large patch in the fall when everything is looking good. 

In addition, the economic downturn has led to severe budget cuts at many facilities, and the poor warm-season grasses are usually the ones that are left to fend for themselves without fungicide protection.

Over the next few weeks, I'll be writing in more detail about spring dead spot and large patch in the warm-season grasses. We'll cover things you can do now and during the growing season to help manage these diseases and how to prepare for preventive fungicide applications this fall. Stay tuned!

Large Patch Resistance of Zoysia?

Last year I suggested that there are differences in large patch susceptibility between Zoysia japonica and Zoysia matrella. A photo of large patch posted last month on the Turf Diseases Facebook page by Dr. Mike Richardson and follow up comments by Dr. Richardson and Dr. Kennelly on the relative lack of resistance they have observed has prompted me to write on this subject again, for all of my observations lead me to believe that there are differences in susceptibility to large patch among zoysia varieties and between zoysia species. Click on the thumbnail images to see photos of large patch on zoysia in Asia, and you will see that the symptoms are most evident on Zoysia japonica:

Why am I convinced that there is some resistance to this disease?

• I've noticed that when Zoysia japonica and Zoysia matrella are growing in the same general vicinity, large patch may be present on Zoysia japonica but not on the Zoysia matrella.
• Research at the Chiba Prefectural Agricultural Experiment Station in Japan has found that there are differences in resistance to large patch among zoysia varieties.
• Dr. Larry Stowell suggested there may be a mowing height effect on the disease where higher cut turf might be more susceptible but a greenkeeper at Japan assures me that at his course it is the Zoysia japonica at fairway height that gets more disease than the higher mown rough.
• Masahiro Kato has published on large patch resistance in zoysia and he found that the differences in resistance among varieties are related to differences in leaf sheath lamination structure.

A Cornucopia of Disease in Southeast Asia

I sometimes find such healthy grass that I have little disease to write about, but this week was an exceptional one. I went from Kanchanaburi to Bangkok, Singapore, and Da Nang, seeing a number of grasses and on them an assortment of pathogens. Click the thumbnails for a full-size image and description.

If there were an award for diseases, seashore paspalum would win this week, with two different unidentified diseases and slime mold and dollar spot, with a bonus for some extraordinary drought stress. In the image below, there is an unidentified patch disease and dollar spot on a seashore paspalum fairway in Bangkok. And you can see the drought stress in the drain lines going to the catch basin in the background. But wait! Can you see the patch of Zoysia matrella in the center-left of the photo? The Zoysia matrella that is free of disease and doesn't have the drought stress of the paspalum even though it is growing in the drain line? Seashore paspalum does not grow well at all in Southeast Asia in areas of low soil moisture content.

Seashore paspalum grows wild in tidal swamps and in intertidal zones. Which is exactly where I found it growing on the beach at Da Nang (below), in its natural environment, and free of diseases. But come in from the beach a short distance, where the high tide does not reach, and I found wiry Zoysia matrella growing in the dunes.

There was brown patch on bermudagrass at Vietnam and bermudagrass white leaf, which I think is the most unsightly disease, on bermudagrass at Singapore and Vietnam.

Most of the diseases, you notice, were on seashore paspalum and bermudagrass. I saw two types of broadleaf carpetgrass this week, both free of any disease. This grass thrives in the umbrageous conditions so ubiquitous in tropical Southeast Asia, as does zoysiagrass.

And for those more interested in cool-season grasses, you probably read with some interest the post from Dr. Kerns and Dr. Soldat a few weeks ago about managing potassium on cool-season turf. I'm fascinated by the Park Grass experiment and its results showing that potassium and lime application cause a proliferation of dandelions and other weeds, and the most recent issue of the Green Section Record has an article with some insights into that experiment and how the results "carry lessons of high importance in the growing of golf turf."

How's the Spring Dead Spot?

This is probably the most common question I get this time of year as everyone anxiously waits to see how much disease there will be this year or if their preventive fungicide applications worked. Based on our winter weather conditions, with cold temperatures combined with periods of wet and dry weather, I expect the disease to be pretty severe this year and early reports seem to indicate that it's going to be a bad year. We've even had a report of a severe outbreak of the disease on zoysiagrass fairways.

Unfortunately, my travel is limited this time of year due to classes and conferences, so let me ask you: How's the spring dead spot out there? Any particular successes or failures with fungicides? Please post a comment to let us know what you're seeing!

When is Scalping a Good Thing?

When is scalping a good thing? When it teaches us something useful. In parks and commercial landscapes in Southeast Asia, the normal maintenance for broadleaf carpetgrass (Axonopus compressus) or manilagrass (Zoysia matrella) involves infrequent mowing at low mowing heights. Grass may be allowed to grow to a height of 30 to 50 mm (1.25 to 2 inches) or higher and then it will be scalped down with a string trimmer nearly to ground level, to something less than 12 mm (0.5 inch). See the video below from a resort at Pai in northern Thailand. I was here recently for some belletristic work.

This scalping would seem like rather poor maintenance, but I suggest that the scalping is a good thing in that it teaches us something about these grass species and their adaptation to low light conditions. Broadleaf carpetgrass and manilagrass tolerate (or even thrive with) this regular scalping, while seashore paspalum and bermudagrass do not. Sure, the average turf quality would be better if the grass was mowed frequently rather than scalped, but this removal of 70 to 90% of the leaf area at one mowing produces a good turf for many resorts and parks and lawns and roadsides in this part of the world.

I like to think about scalping as applying artificial shade to the grass. Shade reduces the amount of light available for photosynthesis. And so does scalping, by removing nearly all the leaves. The grasses that can tolerate scalping in Southeast Asia are also those that are well-adapted to this growing environment. And these are also the grasses that have minimal disease problems and thrive on golf courses. Golf courses planted to bermudagrass or seashore paspalum generally have more disease pressure, whether that be bermudagrass decline or dollar spot or an assortment of leaf spots and other maladies.

Now consider broadleaf carpetgrass (above, on a fairway mowed at 8 mm [0.3 inch] in Hong Kong) and manilagrass, by comparison. These grasses can be scalped. And they are relatively disease-free. Other than fairy ring, I have never seen any disease on broadleaf carpetgrass anywhere in tropical Southeast Asia. In sub-tropical Asia it may suffer from large patch during the short winters. That’s all. The only diseases I have seen on manilagrass in tropical Southeast Asia are fairy ring and curvularia leaf blight. Just those two. Ever. The curvularia leaf blight (see below) only occurs during the rainy season and is relatively easy to control.

Suggestions on the Right Maintenance for the Wrong Grass

Seashore paspalum is a high maintenance grass: to begin with. There is no doubt whatever about that. Frankly, this species is overused (and misused) in Southeast Asia, and thus many golf courses are left with a course requiring more inputs than they are prepared to give. Sure, seashore paspalum can be beautiful, but it is also expensive to maintain, and most golf courses would have better playing conditions for lower cost if they were to use zoysiagrass for fairways and roughs. Let me point out three things about seashore paspalum in Asia that I think everyone should be aware of.

1. Seashore paspalum grows wild in Asia sparingly and only in the wettest areas. However, it is common to find bermudagrass or zoysiagrass growing in all types of environments (sun, shade, wet soils, dry soils) in the wild. Seashore paspalum has been growing in the wild in Asia for well over 100 years but it does not spread except in swamps. There is an excellent paper in Weed Science (Xie et al., 2009) about seashore paspalum and weeds in southern China. The paper is titled "Spatial and Temporal Dynamics of the Weed Community in a Seashore Paspalum Turf" and the researchers set out to measure the spread of weeds through a low-maintenance stand of seashore paspalum at Guangzhou. Weeds were measured every two months during 2007, which was five years after planting, and the turf had not received any herbicides. The somewhat surprising conclusion? I quote: "the seashore paspalum turf has been naturally replaced by manilagrass." Manilagrass is Zoysia matrella. Be aware that seashore paspalum is a grass that will tend to be overtaken by other grasses.

2. Seashore paspalum is pretty, but zoysiagrass is pretty too. And Zoysia matrella has a finer leaf blade than seashore paspalum and is easier to maintain. And some golfers don't like to play from seashore paspalum fairways. Their complaint is that the ball sits too low. Sometimes the seashore paspalum just doesn't want to grow and when that happens the ball sits down a lot more on paspalum than it does on bermuda or zoysia. Here is seashore paspalum at 15 mm and Zoysia matrella at 15 mm. Can you tell which is which? And if you can, is seashore paspalum that much better?

3. My advice for controlling dollar spot on seashore paspalum in Southeast Asia is to increase the growth rate of the grass. On greens and tees, use fungicides as necessary to prevent or control dollar spot. Use a chemical that will control dollar spot, and by all means apply it at the proper rate. On fairways and in roughs, however, it is usually too expensive to apply fungicides to control this disease. Seashore paspalum requires extra care to survive in Southeast Asia or it will be overtaken by zoysia or bermuda. Keep a constant growth rate by applying optimal amounts of nitrogen fertilizer (usually about 3 g N per square meter per month) and maintaining adequate soil moisture. If seashore paspalum growth slows because of inadequate nitrogen or dry soil conditions, it becomes extremely susceptible to dollar spot. Mow frequently with sharp mowers, and that will remove the dollar spot symptoms that do appear.

Mites, a Corpse Plant, and Native Grasses

I was at Bangladesh last week and I saw something that, in years of turfgrass work in Asia, and hundreds of visits to golf courses and other turfgrass sites, I had not seen before. At first, I thought this was a broadleaf weed invading a bermudagrass fairway. From above, this looks a bit like Mimosa pudica, one of my favorite weeds.

In fact, this is bermudagrass, but it is infested with mites, causing a change in the growth habit and drastically shortened internodes. For a closer look, see the image below, with both normal growth and modified growth on the same stolon.

That is definitely not Mimosa pudica! I saw bermudagrass mite damage at Hawaii this spring but the stunting was not so severe and the characteristic "witch's broom" appearance of the mite-infested turf, at Hawaii, was more of a broccoli or cauliflower shape, rather than this compressed and narrow appearance as noticed in Dhaka and Chittagong. My friend Storm Lupier sent me photos showing very similar symptoms on bermudagrass in the Seychelles. And there was similar damage on zoysiagrass turf at Dhaka as well. The two photos above are bermudagrass; the image below is zoysiagrass.

If you have a problem with mites at your course, consult with a local expert or follow the advice in this publication from the University of Florida.

I saw a bit of fairy ring on broadleaf carpetgrass (Axonopus compressus) at Bangladesh and on hybrid bermudagrass at Indonesia this week. The fairy ring disease profile at TurfFiles from NC State summarizes the recommended control measures for fairy ring.

You may be aware of the corpse plant (Amorphophallus titanum -- you can translate that yourself); I have not seen one, and being at Bogor recently, I went to look for one at the Bogor Botanical Gardens. These extensive gardens are 193 years old and have over 15,000 plant species and thousands of orchid varieties. Alas, I did not see a corpse plant in bloom, but I did see pulchritudinous acres of broadleaf carpetgrass, growing in full sun and in the shade of massive tropical trees, and the grass was completely free of diseases. In Southeast Asia, the grasses that grow as native plants here are generally free of diseases when maintained as turfgrass; these grasses are broadleaf carpetgrass (Axonopus compressus) and manilagrass (Zoysia matrella). Sod farms near Bangkok can produce a crop of manilagrass in six weeks using no herbicides, no fungicides, and very little mechanized equipment. See how in this short video:

Large Patch on Zoysiagrass

I visited a golf course at Kanagawa prefecture last week and saw large patch (caused by Rhizoctonia solani) in some areas of the noshiba (Zoysia japonica) rough. What I find especially interesting is what you see in the picture below. The background is Zoysia japonica and has large patch. The foreground is korai (Zoysia matrella) and the disease symptoms are not apparent at all. The patches just stop at the border between the two species of grass.

I usually see large patch on Zoysia japonica and don't recall seeing it (except in pictures) on Zoysia matrella. Large patch development is observed when air temperatures are around 20° C and the disease is most severe in wet soils. You can see in the photo below the severe large patch of a Zoysia japonica rough where the soil is poorly-drained.

In this case again, however, the disease is prevalent on the Zoysia japonica but the adjacent fairway planted with Zoysia matrella is completely free of damage from large patch. The greenest patches of grass in the rough are perennial ryegrass contamination, also unaffected by the large patch, and growing rapidly at an optimum temperature for cool-season grass.

Control of large patch can require fungicide application to the entire golf course. It is consequently an expensive disease to control, and to my eye, one of the most unsightly. But I see it on Zoysia japonica and not on Zoysia matrella. For the breeders, pathologists, and golf course superintendents who have experience with this disease, do you see the same thing? Why do I see large patch on Zoysia japonica while the adjacent Zoysia matrella seems immune? According to textbooks (such as Tani & Beard's Color Atlas of Turfgrass Diseases), both species of zoysia are susceptible to large patch.

The Wow Factor, Seashore Paspalum and Dollar Spot

I hear or read a lot about the "Wow" factor of seashore paspalum (Paspalum vaginatum) in reference to the vibrant green color of the grass, but not so much about the other "Wow" factor associated with seashore paspalum -- it is highly susceptible to dollar spot. And it is dollar spot season now in many parts of Southeast Asia, with temperatures cooling down to 22 or 23 °C at night (about 73 °F) and rising to about 32 °C (about 90 °F) in the afternoons. During the hotter times of the year, when nighttime temperatures are warmer and rain falls more frequently, I see less dollar spot.

Why is that? You may not think these temperatures are cool, but this is the coldest time of year at places such as Bangkok, Ho Chi Minh, Manila, and Hong Kong, so the warm-season grasses (including seashore paspalum) grow a little bit slower. Also, this tends to be the dry season in parts of Southeast Asia, and seashore paspalum eventually slows its growth under deficit irrigation (applied irrigation less than evapotranspiration). So we have plants that are growing a little bit slower, slightly cool nights at an ideal temperature for the dollar spot pathogen to grow, and a susceptible host. It doesn't snow here (One of the many reasons I chose to work in Asia was because of the salubrious climate, so I savor my memories of snowy winters while I enjoy my winters in tropical climates) but sometimes the dollar spot is so severe that a fairway can look as if a light snow has fallen. That is the other "Wow" factor of seashore paspalum.

Seashore paspalum is generally quite susceptible to dollar spot, although there are differences among cultivars. Dr. Bryan Unruh's research with different seashore paspalum varieties in Florida (the research paper is available for download here) shows big differences among cultivars. SeaIsle Supreme was especially susceptible to dollar spot; SeaDwarf and SeaSpray were among the varieties with the lowest incidence of dollar spot. Dr. Philip Harmon has written a good reference on seashore paspalum diseases. That article was just published in the Green Section Record (download Challenges and Opportunities: Disease Management for Seashore Paspalum in Florida).

In the warmer parts of Southeast Asia, where the nighttime temperatures rarely drop below 20 °C, dollar spot on seashore paspalum can usually be managed (at least on tees and fairways) with minimal fungicides. If we can accept some damage from disease, applications of fertilizer and water to stimulate more rapid growth will usually allow the turf to grow faster than the dollar spot can damage it. In cooler parts of Asia, where seashore paspalum growth is more restricted in winter, then fungicides may be required to control the disease. On greens there is rarely a situation when the risk of severe dollar spot infection can be tolerated, so fungicides are almost always required on a preventative basis.

My management suggestions are:

• monitor the turf growth rate and scout for dollar spot daily
• on fairways and tees, apply fast release nitrogen (sources such as ammonium sulfate, urea, or calcium nitrate work well) to stimulate growth when dollar spot infections are more than you wish to tolerate
• ensure that soil moisture levels are in an optimum range for seashore paspalum growth
• on greens, follow the same practices and use fungicides as necessary to control and prevent additional infections

One thing to note is that bermudagrass and zoysiagrass are relatively immune to dollar spot in Southeast Asia. On golf courses I have never seen that pathogen on those grasses. So keep that in mind when choosing grasses for your course. If seashore paspalum is chosen for the "wow" factor of color, you may also see the "wow" factor of snowy fairways. With zoysia in January (see below), very little maintenance is required but the grass provides a great surface.

Large patch is brewing in the warm-season grasses

With cool, wet weather setting in across much of the southeast, now is the time to initiate a preventive fungicide program for large patch on the warm-season grasses. Zoysiagrass, centipedegrass, and St. Augustinegrass are most prone to this disease; large patch rarely causes significant damage to bermudagrass turf. Not all turf needs to be treated with fungicides to control large patch, but areas that have sustained severe damage in the past should be sprayed on a preventive basis.

One great advantage of the warm-season grasses is that they are fairly resistant to diseases; in most parts of the southeast, we only need to worry about one or two diseases on these grasses. Spring dead spot is a major problem on bermudagrass, and large patch can cause severe problems on all the others - zoysiagrass, centipedegrass, and St. Augustinegrass.

One problem with large patch is that it comes at a time when the warm-season grasses are shutting down for the winter or greening-up in the early spring. As a result, the potential for recovery once symptoms appear is slim to none. Once an outbreak occurs, you're probably going to be looking at those symptoms until April or May when the turf really starts growing again.

The other problem with large patch is that the appearance of symptoms is very unpredictable. Sometimes they appear in late summer, other times during the fall, and in many cases no symptoms are observed in the spring. So how are you supposed to prevent the symptoms if you don't know when they are going to appear?

The answer is easy - don't time your fungicide applications based on when symptoms have appeared in the past. Instead, you should time applications based on when the pathogen is active. As it turns out, we know that the large patch pathogen becomes active when soil temperatures consistently dip below 70 degrees at the 1 to 2 inch depth. In other words, NOW IS THE TIME TO START PREVENTIVE PROGRAMS FOR LARGE PATCH IN MANY AREAS!

There has been much confusion over the name of this disease, and as a result, very few fungicides are specifically for 'large patch'. Some labels still refer to the disease as 'brown patch', whereas others call it 'zoysia patch'. Since they are all caused by Rhizoctonia solani, any fungicide that has one of these diseases on the label can be used for large patch control.

In some cases, one well-timed fungicide application in the fall can provide season long control of large patch. However, in severely affected sites, where disease pressure is high, repeated applications are often necessary. Two applications in the fall, 4 to 6 weeks apart, and one application in the spring when the turf is nearing full green-up is the ideal program. If three applications are not possible financially, the fall applications are probably more important than the spring application.

Strong brown patch fungicides like Heritage (0.4 oz of 50WG or 2 fl oz of TL), Insignia (0.9 oz) and ProStar (2.2 oz) are very effective for large patch control. Some of the DMI fungicides, Bayleton (1 oz) in particular, have performed very well also. Recent trials have also shown that Headway (3 fl oz), a pre-mix of Heritage and Banner, is a very effective large patch fungicide.

For more information about large patch management with fungicides and cultural practices, please refer to our Large Patch Disease Profile on TurfFiles.

K-State research update

Hello,

This week I thought I'd give a photo tour of a few of our turf projects here at K-State. Our turf field day is coming up on August 6th at the JC Pair Horticulture Center in Wichita. The photos show some of the studies here at the main campus.

1) Zoysia sun/shade study

About a month ago we installed a sun/shade study for different zoysiagrass lines. The study was conducted in 2008 and is being repeated this year. Dr. Jack Fry is the lead on this, with PhD student David Okeyo in charge of the data.

The photos show the plots on the day of installation.

We’ll be looking for differences in growth rates/establishment, quality, etc. There are a lot of shady sites out there, and it would be nice to have some options.

2) Bentgrass cultivar trial: management for dollar spot

KSU is working with several universities and other partners in the region to examine dollar spot susceptibility in different cultivars. We have the cultivars at both greens-height and fairway height. M.S. student Cole Thompson is the lead worker on the project here at KSU. With the cool temps, some dollar spot is now appearing in the more susceptible plots. See the image below.

3) Brown patch fungicide trial

We just initiated a new brown patch trial in lawn-height tall fescue. There aren’t too many obvious patch symptoms right now, but brown patch lesions are present and once it gets hot again the patches will likely follow. Graduate students Cole Thompson and Ken Obasa are assisting with this study.

4) Putting greens and DMI PGR effects

In the trial shown below, on A4, we have some treatments that include two DMI fungicides. As you probably know, DMI fungicides can have plant growth regulating (PGR) effects especially in mid summer. In the center you can see an off-color due to PGR effects. Those particular plots are receiving propiconazole and the others are receiving triticonazole which is not showing PGR effects at the moment. In trials at other universities, though, this active ingredient has caused PGR effects. For more info on DMI’s in mid summer, you can look back at Lane’s posting on June 16th.



5) This is our rain-out shelter. There is a rain sensor on the back. When it rains, the shelter slides forward on the rails, preventing rain from landing on the plots. That way we can control how much water is applied to each plot. In the photo you can see the small plots of different colored turf. There are replicated plots of different types of bluegrass. Dr. Dale Bremer and PhD student Jason Lewis are looking at drought tolerance/water use. The rainout shelter, shown here on a sunny day, is getting a real work-out with all the rain this year. Still, there have been opportunities to let the turf dry down and examine differences.

more moss madness

Hello on this last Friday of May. Me, I’m not mentally prepared for the fact that it will be June on Monday.

DISEASES

On the disease side, we’re still seeing large patch in zoysiagrass but the grass in the centers is starting to recover (see photo). I even had a sample of large patch from a zoysia home lawn, which is not very common. I’m also seeing continued spring dead spot in bermudagrass.

We finally have the first dollar spot activity at our turf research facility, and our first applications for summer trials went down yesterday. I accidentally hooked up the wrong nozzles at first, but we quickly sorted out the problem ("Hmm, why is there so much solution left in the bottle?"), exchanged nozzles, and everything was fine.


MOSS:

I made a few comments on moss last week, and I thought I’d share a few more.

1) How does moss spread?

Most mosses can spread by two mechanisms, vegetative (asexual) as well as sexually.

With vegetative spread, little chunks of the moss tissue physically break off and spread as clones (=genetically identical) of the mother plant. This probably happens on mowers and other equipment as well as rainfall. The first photo is little moss chunks floating in rainwater. That photo was sent to me by my colleague Dr. Derek Settle of the Chicago District Golf Association.

This kind of spread is somewhat analogous to turf pathogens such as Sclerotinia homoeocarpa (dollar spot) or Rhizoctonia solani (brown patch) which do not produce spores but rather spread as chunks of mycelium or sclerotia.

The next photo shows the sexual stage of moss. Moss plants produce male and female gametes which combine to form this small stalk with a capsule at the top. This life stage is called the sporophyte. In the capsule, spores are formed. The spores then disperse and form new gametophytes (the typical cushion-type growth).

2) Where are mosses found in nature?

Most mosses are found in moist environments. The old adage is that if you are lost and can’t determine compass directions, you can look for moss on tree trunks. Since moss prefers shade, the moss is most likely to be on the north side. I’ve never been lost enough to resort to that, but I have seen the pattern.

However, the most common moss on golf courses, silvery thread moss (Bryum argenteum) seems to be happy almost everywhere. It can tolerate heat, drought, and extreme cold. Silvery thread moss is actually a dominant plant species in Antarctica! Throughout the world, it has been found on mountain tops and at sea level. No wonder this stuff can be such a pain. It can thrive anywhere.

3) “Where is Moss Man?”

This question was posted by my colleague Frank Wong. Awhile back, I shared with Frank and some others that while thinking about moss I had a sudden flashback to my youth and the character “Moss Man” on the cartoon “He-Man.”

You can find information about Moss Man on Wikipedia, and I just checked eBay, and you can buy your very own action figure there, unless I beat you to it.

Update from Kansas

Hello,

It's Friday, it's Friday, and a beautiful day it is here in Kansas. Lucky me, I have some field work scheduled for the day.

The spring rains are continuing. Large patch of zoysia is popping up all over, including in our research plots (see image). While pulling some samples of large patch in zoysia at a golf course, I also found some rust (see image).

Now that the bermudagrass is greener, symptoms of spring dead spot are becoming more apparent.

Though dollar spot is not yet active at our research facility, I heard from a superintendent that they had dollar spot active on most greens.

Here in Kansas, it's time to be thinking about summer patch in sites that have a history of this disease. For more information, you can check out this website:

http://www.plantpath.ksu.edu/DesktopModules/ViewDocument.aspx?DocumentID=986

It focuses on Kentucky bluegrass but information is relevant to other grasses as well.