Is it Starting to Feel Like Groundhog Day?

So I bet many of you in the south are feeling like Bill Murray in the 1993 movie “Groundhog Day”. I know I am. Everyday we look at turfgrass samples with the same problem. Heat-related stress and decline and severe nematode populations! Many superintendents that I have spoken to are getting as frustrated as me. This heat is getting old. We are now sitting at 45 days above 100F here in Stillwater. In the Oklahoma City area they are knocking on the all-time record of 50 days! Everyday the same thing…

The OSU Turfgrass Diagnostic Laboratory has churned through a bunch of creeping bentgrass putting green samples in the last couple of weeks. The large bulk of samples have extremely short root systems. The heat has really taken its toll on creeping bentgrass in much of the south central U.S. Throw in some nematodes damaging what roots are left and we have a lot of turfgrass in serious decline. Very high populations of stunt (Tylenchorhynchus spp.) and ring (Criconemella ornata) nematodes have been observed in many of the samples submitted. We have seen populations of stunt nematodes as high as 4,000 individuals in 100 cc of soil. This is about 26 times the threshold we consider the “danger zone” on creeping bentgrass. Ring nematode populations have been coming in as high as 2,000 individuals per 100 cc soil, which is about four times the “danger zone” population level. So as you can see, things are getting tough here at the end of the summer in the south. Many are praying for cooler weather and rain. Although, those that have gotten rain have been struggling with wet greens and hot weather, which makes for a whole different set of hurdles.

Other issues in the diagnostic lab have been few and far between, but we did have one sample with Pythium root rot. This was an odd situation where the greens got dry and severe wilt began. To compensate the newly hired assistant superintendent turned the irrigation system on and severely over-irrigated multiple times. When you have lots of soil moisture and high temperatures in the rooting zone, Pythium root rot can help finish off the already declining plants. So while, not the initial cause of the problem, we did identify something other than nematodes. In our research plots, brown patch has also been active and dollar spot comes and goes pretty much as the humid weather comes and goes.

The long-term forecast is showing cooler temperatures, if we can just get through this weekend. As Dr. Kaminski has said in a previous post “there is light at the end of the tunnel.” So keep your head up and your fingers crossed for cooler temperatures, I think we will be there soon!

Getting Out of Hot Water

Greetings. My name is Lee Miller, and I am the extension turf pathologist at the University of Missouri. I was invited to post a few weeks ago, and gratefully accept the invitation. Every once in a while I’ll join in on the fun with my fellow Midwest colleagues (Drs. Kennelly, Kerns, and Smith) to relay on some of my experiences from the region.

As Damon (and the rest of the world) noted, it is hot almost everywhere in the U.S. and creeping bentgrass is dancing on the coals. Frequent syringing of greens is a must, but with this extreme heat, the water coming out of the hose may also be too hot for comfort. During our historically hot summer of 2010, some Missouri superintendents were reporting 90F + water temperatures in their irrigation lakes and coming out of their syringing hoses. That’s not much relief! In addition, traditional syringing can be difficult to master and often times oversaturated root zones can be a side effect. Hot water in a stressed root zone is a recipe for trouble, and turf pathogens love troubled turf...

A local assistant superintendent has rigged up a misting system hooked up to a Buffalo blower to combat the problem. The system has two holding tanks in the back that hold water that is cooled with block ice. Pumps deliver the water to the mouth of the blower, where it is atomized and blown across the putting green (similar to the fan systems that cool off football players on the sidelines). This is not a new idea. In 2006, Patrick Gross wrote a USGA Green Section article on a misting system implemented at Mission Viejo Country Club.

I produced a short video below showing the system in action, and recorded some before and after canopy temperatures taken across the putting surface. This is not a scientific study by any means, and doesn’t compare this practice vs. normal syringing. From a pathological perspective though, I like this cooling method because it allows for more control over root zone moisture. Most of the samples I have looked at this season have very saturated root zones, and as a result, black layer and Pythium root rot have been diagnosed routinely.

I’d like to hear some comments from those that use a misting system and how you have implemented it into your program.

Beautiful Weather, Finally?

This spring has been one of the coolest and cloudiest on record. Just last week I was in Stevens Point, WI and soil temperatures barely reached 60 F. Still prime time for take-all patch and fairy ring preventative applications. To be honest not much is happening around the Upper Midwest. We have had reports of brown ring patch, but thats about it. Derek Settle at the CDGA has reported brown ring patch and a bit of dollar spot. We have seen and heard of multiple cases of creeping bentgrass turning red this spring. We think it is a combination of proxy/primo or trimmit + DMI fungicides for take-all/fairy ring + cool temperatures. The symptoms are typically seen on older leaves and we cannot find spores of any kind in the samples. An image of the symptoms we are seeing is above, sorry the image does not show the symptoms very well. If anyone has any thoughts on this matter they would be welcomed and appreciated!

Finally I thought I would reiterate a former post Lane wrote. He presented a succinct description of diseases that typically affect creeping bentgrass and annual bluegrass putting greens. There has been concern in the Midwest with the substantial amounts of rainfall we have received that Pythium root rot could be a problem. Yes Pythium root rot could occur at anytime as long as the soils are saturated, but considering creeping bentgrass and annual bluegrass grow well during the spring I rarely think of Pythium root rot as an issue. This brings me to another point Lane made in a previous post, is Pythium root rot a disease. I think it is a disease because we would not see symptoms characteristic of root rot if the pathogens were not present. Keep in mind though once/if summer rolls in and we continue to receive significant rainfall, then we might see issues with this disease. I am not saying that fungicides are not warranted, but I do think it is unlikely that Pythium root rot would/did occur this spring in the Midwest.

Not All Pythium Diseases are Created Equal

With the excruciating heat and humidity plaguing the Northeast, Southeast and Midwest, there has been numerous mentions of the notorious Pythium. Even the news media has caught wind of this nasty fungal-like organism (maybe that's why the columnist called it a bacterium). Check out Lane's post this week if you want to see what I am talking about.

So why are Pythium diseases problematic when the temperatures rise and relative humidity is through the roof? Pythium species are members of the Oomycota, which are commonly called water-molds. These organisms used to be classified as true fungi, but morphological and molecular evidence show that members of the Oomycota are more closely related to diatoms and brown algae. Yeah I know you don't care, but I do believe in the quote from The Art of War by Sun Tzu- "Know thy enemy and know thy self and you will win a hundred battles." It is vital to understand the pathogens you fight on a daily basis.

We have seen a number of different diseases induced by Pythium species, such as Pythium blight, Pythium root rot and even Pythium root dysfunction. However, the symptoms, signs and conditions favorable for disease development are different for these three diseases. Considering the recent weather conditions, I thought it would be good to review the differences between these diseases as well as the management strategies.

Pythium Blight- This disease has been the subject of nightmares for golf course superintendents for years. The fear most likely steams from the days when Pythium aphanidermatum developed resistance to metalaxyl and entire fairways were wiped out rapidly. Today we rarely hear of entire fairways devastated by Pythium blight, but the disease can develop even the Upper Midwest. However, the development is typically centralized around a drain or low lying area. If the disease is not controlled and hot, humid conditions persist the disease could spread at an alarming rate. Usually we only have 2 to 4 weeks of heat and humidity conducive for Pythium blight development in the Midwest, yet this summer has been a bit different than normal.

The symptoms of Pythium blight start as small, gray spots that can coalesce into larger areas of blight fairly quickly. Typically development of this disease will occur around drains or low lying areas of fairways. The picture just above the heading of Pythium blight is typical of the symptoms we see on creeping bentgrass in the Midwest. Cottony, white mycelium may also be present during early morning hours when dew is present. As for management, its a good idea to start thinking about Pythium blight when nighttime temperatures are above 70 to 75 degrees and when there is plenty of soil moisture. Fungicides that work best are Subdue MAXX, Stellar and Segway. Other products that may have varied results are Banol and Terrazole. Keep in mind that Signature works, but only when pressure is light to moderate.



Pythium root rot- Pythium root rot can be a major problem of golf course putting greens when there is persistent heat, humidity and low light intensity. This disease is also a problem on putting greens with limited air movement. One of the major problems with this particular disease is we know very little about the pathosystem. Consequently most the control recommendations are based on observations made by golf course superintendents. I think Lane posted about Pythium root rot sometime last summer and talked about the issues surrounding this disease.

The symptoms are usually diffuse, irregular areas that exhibit decline. The affected areas can decline quite rapidly because the pathogens destroy root tissue. The picture above is an example of typical stand symptoms. A noticeable decline in root depth is usually observed within affected patches. If you suspect Pythium root rot is an issue at your course, I suggest sending a sample to your local turfgrass pathologist for confirmation. Usually the best medicine for Pythium root rot is a Terrazole drench. Unfortunately, this disease can still develop even if you are on a good Pythium preventative program. Remember that most turfgrass fungicides only move up from the point of absorption, so in order to get Pythium root rot activity the fungicide needs to be washed into the rootzone.

Pythium root dysfunction- I know this is confusing, but Pythium root dysfunction is a totally different beast that Pythium root rot. The conditions that favor Pythium root dysfunction (PRD) symptom develop are hot, dry conditions not hot, humid conditions. PRD shows its ugly head on upland areas and develops into a discrete patch. Normally this disease is problematic for young putting greens built with high-sand content rootzones. I have blabbed on for a while on this post so check out a previous post by Lane for PRD management strategies.

To bring this belaboring post to an end, if you suspect any Pythium induced disease have it diagnosed by your local turfgrass pathologist. These diseases should not be taken lightly and all of them have different management strategies.

NO WIND = DEAD GRASS

I'm back.

For those of you who were hoping that my first post would be on bacterial wilt, I am sorry to disappoint you, but we have more important problems here in the Southeast right now.

Several years ago, I got a call from an angry homeowner who lived in a golf course community. The golf course superintendent had installed a fan adjacent to the green in her back yard. Said fan was preventing her from enjoying her patio, keeping her awake at night, and reducing the value of her property.

She must have been a scientist of some sort, because she asked me if I had a mathematical model that could be used to determine if a fan was necessary. So I broke out my plant physiology, meteorology, and calculus books and after several weeks of analysis, I came up with the following equation:

NO WIND + HEAT = DEAD GRASS

I don't think she liked that answer because I never heard from her again. But this summer is proving my equation to be correct: I have never seen fans make such a huge difference in the survival of creeping bentgrass putting greens as they are this year. Just about everywhere I've visited, the creeping bentgrass being impacted by fans is relatively healthy, whereas the turf furthest away from the fans or on greens without fans is really struggling.

It's been a difficult summer and there's no sign of it getting any easier. But if one positive thing can come out of it, we can use it to demonstrate the benefit of turf fans, fine tune the placement of existing fans, or fight for the money to install additional fans. Don't miss this opportunity!

On the disease side, a number of superintendents in our area are still struggling with Pythium root rot, and some summer patch is also showing up on creeping bentgrass greens. For more information about these diseases, please see the following post from last year.

We have also seen a couple of cases of Rhizoctonia zeae on creeping bentgrass greens. This pathogen induces similar symptoms to brown patch, but is active at higher temperatures and the patches or rings have more of an orange coloration. Most fungicides labeled for brown patch will provide good control of R. zeae, but this pathogen is not sensitive to thiophanate-methyl and is less sensitive to iprodione so you should avoid these products.

Pythium Root Rot....Is it a disease or not?

Hot and wet weather during July and August typically brings outbreaks of Pythium root rot on creeping bentgrass and bermudagrass putting greens in the Southeastern United States. Symptoms of this disease usually appear as a yellow to orange, irregular dieback that is most severe in poorly drained or stressed areas. In some cases, however, Pythium root rot can develop in distinct spots and patches. These patches may be yellow, orange, or even purple in color.

Pythium root rot requires wet soils in order to develop, either from poor drainage, over-irrigation, or frequent rainfall. In fact, some pathologists argue that Pythium root rot isn't a real disease; they believe that the saturated soils are killing the turf and that the Pythium is simply colonizing dead roots. It's a 'chicken and the egg' type argument - no one knows for sure which came first.

I tend to believe that Pythium root rot is a real disease, simply because curative fungicide applications help to stop the problem and encourage turf recovery. That being said, if you have chronic problems with Pythium root rot, the only effective way to manage this disease long term is to improve soil drainage. All of the fungicides in the world will not provide adequate control if the soil is continuously saturated.

From the descriptions above, it is clear that Pythium root rot symptoms are highly variable and can be confused many other problems. Because of this, it is almost impossible to definitively diagnose this disease in the field. Curative fungicide programs for Pythium root rot are expensive, so a misdiagnosis can be costly. If you suspect that you have Pythium root rot, send a sample to a diagnostic lab for confirmation.

Few fungicides are labeled for Pythium root rot control, and there is virtually no scientific data regarding their effectiveness. For preventive applications, applications of mefanoxam, fosetyl-Al, or propamocarb every 14 to 21 days are recommended. An occasional application of ethazole is never a bad idea, especially during periods of wet weather.

For curative applications, I recommend an application of ethazole to provide quick knock-down of the disease, followed a few days later with a mefanoxam application. This is a program that I 'borrowed' from Bruce Martin at Clemson several years ago, and it works like a charm.

To minimize the potential for foliar burn, ethazole must be watered-in immediately after application with at least 1/8” of water. Applications of mefanoxam or propamocarb should also be watered-in, but fosetyl-Al should be applied to the foliage for best results.

For more information about Pythium root rot, please refer to TurfFiles.

Summer Fungicide Programs for Cool-Season Putting Greens

Summer is approaching quickly in the Southeast, and golf course superintendents are shifting their focus from growing grass on bentgrass or Poa greens to just keeping them alive. Having a solid fungicide program in place to control summer diseases is an essential part of this. Here are a few diseases to keep in mind as you put your program together:


Pythium blight. While this is a major concern on Poa greens, Pythium blight is not a common problem on creeping bentgrass. A huge amount of money is wasted every year to control Pythium blight on bentgrass greens. If you have Poa greens, keep in mind that although several of the QoI fungicides are labeled for Pythium blight control, they only provide 7-10 days of protection.

Pythium root rot. This is a persistent problem on bentgrass and Poa greens that are poorly drained. However, Pythium root rot can also occur even on well-drained greens during periods of wet weather, so nobody is immune. Of the Pythium fungicides, mefanoxam (Subdue, Fenox) is most effective against Pythium root rot. For curative control, we often recommend an application of ethazole (Koban, Terrazole), followed a few days later by mefanoxam. Remember that these applications should be watered-in since the pathogen is active in the soil.


Pythium root dysfunction. For golf courses with bentgrass greens less than 10 years old, Pythium root dysfunction is the most common problem during summer. This disease is best managed during the fall and spring when the pathogen is actively infecting roots. If symptoms are observed during the summer, relieving stress by raising mowing heights and increasing fertility levels is essential. Curative applications of Insigna, Segway, or Signature + Banol can also help to suppress symptoms, but only if steps are taken to relieve stress at the same time.


Anthracnose. This is a major concern for those with Poa greens and older cultivars of creeping bentgrass. Golf course superintendents are running out of options for anthracnose control due to fungicide resistance. Most anthracnose populations are already resistant to the benzimidazole and QoI fungicides, so do not rely on these products unless you know that your population is sensitive. The NC State Turf Diagnostics Lab offers fungicide resistance testing if you would like to find out for sure. Fortunately, most new bentgrass cultivars are very resistant to anthracnose so this disease is becoming less common in the southeast.


Fairy ring. Hot and dry weather during summer tends to bring out Type I fairy ring symptoms, decline or death of turf in ring patterns. In most cases, symptoms are the result of hydrophobicity that has developed in the thatch layer. Fungicides are not very effective for curative suppression of fairy ring, unless they are combined with wetting agents or cultivation practices to re-wet the soil profile.

Nematodes. These are a common problem on sand-based putting greens across the southeastern United States. In fact, I am convinced that nematode problems are much more common and widespread than anyone realizes. If you've never had a nematode assay done, I'd encourage you to spend the $5 or $10 to do one. You may find that chronic problems you've battled over the years are actually the result of nematode activity. While the options of nematode control are limited at this time, effective products are on the horizon.

Brown patch. Thanks to the QoI fungicides, brown patch is no longer a significant problem on putting greens. As long as you rotate the QoIs or other strong brown patch fungicides (chlorothalonil, ProStar, Endorse, Medallion) into your program once in a while they will keep brown patch in check.

Should I water that in?

This is easily the most frequent question I get from golf course superintendents during the growing season. It is a difficult question, and there isn't always an easy answer.

We know that watering fungicides into the root zone is important for effective control of root diseases. However, in the real world, golf course superintendents apply fungicides to control a combination of root and foliar diseases, but we don't always know what effect watering-in has on foliar disease control.

To answer this watering-in question, you need to identify the primary disease you're trying to control, know where this pathogen attacks the turf plant, and understand how the selected fungicide moves in the plant after application.

In most cases, if a root disease is the primary target for a fungicide application, then it should be watered-in immediately after application. Once the spray dries on the leaves, it will be locked into the foliage and will not get into the root zone. Exceptions to this rule are the true systemic fungicides, like fosetyl-Al and the phosphite salts. These products are translocated downward in the plant and do not need to be watered-in.

The Fungicide Selection Tool, a new feature on our TurfFiles website, can help you select the best application technique for your fungicide applications. After selecting your turf species and the diseases you are trying to control, a list of fungicides is displayed. The list is ordered based on average efficacy against the selected diseases. After selecting a product or products to apply, you are taken to a page that displays mode of action, efficacy rankings, risks for fungicide resistance, rates and application intervals, and application instructions for each selected disease.