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Please note that we have moved from www.turfdiseases.blogspot.com to www.turfdiseases.org. We will leave this site up live in case there in any information here that you find useful, but all posts have been transferred to the new site. We hope you visit us at our new location and that you like the additions of the new website.

No kind words for September

The average high for yesterday (Sept 1) is 87. We beat the old record (107) with a high of 108. Yuck. I kept thinking "Just wait til September... just wait til September." Well, September, I have some special words for you, but I'm too much of a lady to type them in this public blog. Click on the image below to zoom in on our summer-of-fun. This particular data is from here in Manhattan.




This time of year can be marked by extremes. The record lows are in the 40's, but there have been triple digit record highs almost all through September. Wild mood swings.

Fungicide trial

This year my PhD student Ken Obasa and I have been conducting a fungicide study on the putting green looking at a couple of fungicide programs, and a new product called Velista which should be released soon. All treatments are applied every two weeks. Velista is tested at 0.3 and 0.5 oz/1000. Here are the programs:

Program 1:

10 May Honor 1.1 oz

2 June Insignia SC .7 oz

17 June Spectro 90 5.75 oz

30 June Signature + Daconil 4 oz + 3.2 oz

14 July Insignia SC .7 oz

28 July Signature + Daconil 4 oz + 3.2 oz

11 Aug Chipco 26GT 4 oz

25 Aug Honor 1.1 oz

Program 2:

19 May Headway 3 oz

2 June Heritage TL 2 oz

17 June Spectro 90 5.75 oz

30 June Signature + Daconil 4 + 3.2 oz

14 July Heritage TL 2 oz

28 July Signature + Daconil 4 oz + 3.2 oz

11 Aug Chipco 26GT 4 oz

25 Aug Headway3 oz

Program 3:

19 May Disarm M 1 oz

2 June Disarm .36 oz

17 June Spectro 90 5.75 oz

30 June Signature + Daconil 4 + 3.2 oz

14 July Disarm .36 oz

28 July Signature + Daconil 4 + 3.2 oz

11 Aug Chipco 26GT 4 oz

25 Aug Disarm M 1 oz

Program 4:

19 May Tartan 2 oz

2 June Compass .25 oz

17 June Spectro 90 5.75 oz

30 June Signature + Daconil 4 + 3.2 oz

14 July Compass .25 oz

28 July Signature + Daconil 4 + 3.2 oz

11 Aug Chipco 26GT 4 oz

25 Aug Tartan 2 oz

We had a severe brown patch epidemic in early/mid August, and brown patch reached about 40% severity in the untreated plots. All the programs and the two Velista treatments held the disease to 0%.

Dollar spot pressure has been fairly low but with cooler temperatures I suspect it will flare up in the next week or two and probably though most of September. I’ll post some details later on.

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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.

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!

Greetings from Canada

Hello there! My name is Katerina Jordan and I am a turfgrass scientist at the University of Guelph in Ontario. I was asked to be a part of this blog and am posting a brief introduction for those of you who don’t know me.

Most of Canada has a much shorter season than in the States, but our superintendents are no strangers to a wide variety of diseases on their turf. This season has been a tough one for managers here in Ontario as we experienced a cool, wet spring followed by some of the hottest temperatures on record combined with prolonged periods of drought. Many turfgrass managers in the U.S. are used to excess heat and drought, but for most of Canada this kind of summer is very foreign to us. On the up side, the lack of moisture has kept a number of diseases at bay, but the turf (epecially the Poa annua) is suffering quite a bit from the prolonged stress. Fortunately, we are headed into the end of our summer as temperatures start to drop significantly by mid-August.

Major issues that we deal with here are dollar spot and anthracnose throughout the country, take-all patch and summer patch in Ontario as well as some of our prairie provinces (Alberta and Saskatchewan) due to very high soil pH levels, and plant-parasitic nematodes in British Columbia, the eastern provinces and here in Ontario. However, the diseases that we deal with the most in the colder provinces are the snow molds – both gray and pink.

I look forward to updating readers to goings on here in Canada based on discussions with superintendents and from the samples we receive in our diagnostic lab.

Good luck with the rest of the season!

A plant pathologist's dream come true - patch-a-rama

Hello out there,

I don't have too much to report, but we are having an impressive outbreak of brown patch this week at our research facility. I wanted to get a lawn chair and just sit out there on the research green and take it all in. Here are some images, smoke-rings included.

With moss:

With dollar spot:

With scalping injury:

The temperatures have dropped, with highs in the coming days in the 90's and even some 80's in most of Kansas. In southern Kansas it looks like there will be a few more days of ~100 then some 90's and 80's. Poor Oklahoma still looks super hot, though. Ugh.

Some parts of Kansas also got some rain yesterday and today, but many areas missed out. Our KSU turf field day got rained on yesterday in the Kansas City area.

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Light at the end of the tunnel (e.g., It's August)

It's been a busy week for golf course superintendents in the region as diseases are in high gear and the heat and temperature stress are causing many golf course putting greens to decline. We are hearing a lot of reports of yellowing and discoloration to bentgrass putting greens, possible nematode issues, and the typical diseases that we would expect to see at this time of the year.

Rain storms that swept through much of the mid-Atlantic provided some much needed relief from the drought we were in, but in many cases the rain fell too fast and basically moved via the surface. The good news from that was that many of you who had ponds that were getting low got a "refill". The bad news is that this did little for replenishing the soil and also washed out a few hundred bunkers. There were even reports in parts of southeast PA of flooding due to the massive storm that came through last week. On the other hand, there were also courses that DID manage to get the slow and steady rain that helped to wet the soil. Following these rains, dollar spot became VERY active and anyone not covered with fungicides saw cotton candy fairways on Tuesday.

Heat stress continues to be the biggest issue throughout much of the region and I can't stress enough that just because the turf is declining doesn't mean that it is pathogen related. In many cases, the soil temps are just too high and/or the growing environments too poor. As we hit the home stretch of summer, it is important to continue to be diligent on your water management. Yes, I know that it is not practical for many of you to get out there and hand-water everything as the courses with a $2,000,000 budget do, but the bottom line is that if you are using your overhead irrigation to "syringe" then you are probably over watering (this was from a USGA agronomist who I believe it going to write an article about it for an upcoming issue of the USGA Record).

Active right now: dollar spot, brown patch, Pythium blight, anthracnose, fairy ring, summer patch, others?

Website update: We are in the process of finalizing the details/construction of the new website for Turf Diseases. Some planned features include:

• More authors for more updates
• Restructuring of regional updates in line with USGA Regions
• New "Research" section for the latest research updates from the scientists
• New "Tech" section (you'll have to wait for the launch to find out more)
• Disease profiles and Image galleries
• Disease updates from superintendents

Hot

Hello everyone.

Wow, I can't believe it's the last Friday in August. Where has the time gone? Here at KSU we are gearing up for our field day which will be Thursday, Aug 4, over at the Olathe Horticulture Center (near Kansas City). For me, field day always indicates that there are only a few more weeks to get through before cooler temps set in.

Here is a summary of recent high and low air and soil temps here in Manhattan:

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You can see we've had a lot of 100+ days. And, perhaps more importantly, we've had some very "high lows". That is, the overnight hours don't provide much relief.


I have just a few photos from the past week.


As far as diseases go, brown patch continues to be active.

Anthracnose spore-producing structures in creeping bentgrass sample

Hydrophobic soil

From the landscape side of things:

Geraniums bleaching out from the heat. I’ve seen this in greenhouses where there were heater issues. I’ve never seen it in the field. But, it's been stinking hot. The plants should recover and be just fine.

Alcoholic slime flux. No, that is not John Kaminski's new favorite drink. (Or, is it?). If you put one of those little umbrellas in it... maybe.

Imprelis Update

This is an important news update from Dupont related to the suspected issues surrounding Imprelis.

Below is from their newly launched website called www.imprelis-facts.com.

"DuPont is fully committed to making sure that our valued customers are satisfied with our products, and to ensuring the responsible stewardship of those products. We regret any injury to trees that our herbicide, Imprelis®, may have caused. We have reached out to lawn care professionals who have reported concerns, and are committed to working with them to promptly and fairly resolve any problems associated with those products.
We have created this website to provide up-to-date information about Imprelis®. We also want to make it easier for lawn care professionals and homeowners to report any problems they have encountered.
If you have a problem, we would like to hear from you. Please go to the “Contact Us” tab of this website to report any problem. In addition, we will be launching a toll-free hotline on Monday, August 1. We will post the number on imprelis-facts.com. Please continue to check the website for updated information."

More on Nematodes in The Southern U.S.

The heat is still cooking us here in Oklahoma and the rest of the south-central U.S. We also have been receiving many samples in the OSU Turfgrass Diagnostic Laboratory. Most of the samples are suffering from severe heat-related stress. This past weekend has been one of the hottest we have seen yet here in Stillwater. According to the Oklahoma Mesonet station summary for Stillwater, we topped out at 105 F on Saturday and 107 F on Sunday. As I said in my previous post, if you are experiencing these temperatures and still mowing everyday at ultra-low heights, making cleanup passes on edges of greens, have your grooved rollers on, and are doing anything else that causes unneeded stress on turf plants, STOP! These practices will facilitate a quick decline of putting greens under these sustained high temperatures and there is nothing you can do to facilitate recovery until cooler temperatures (high temperatures less than 85 F) prevail.

In addition to samples that are under severe heat stress, we have been receiving many samples with high nematode populations. I talked about this in another post and Dr. Tomaso-Peterson also wrote a great synopsis on nematodes. We have been receiving some questions on how nematodes cause damage to plants so I’ll attempt to explain a bit using creeping bentgrass as the host of interest.

Nematodes cause damage on creeping bentgrass by feeding on the roots. Feeding by these tiny animals (roundworms) can injure and impair root functions such as water and nutrient uptake. Nematodes may feed externally or internally. Utilizing a specialized spear-like feeding structure (stylet), nematodes puncture plant cells in the roots, causing discolored areas (lesions) or swellings. Nematode activity also can predispose the grass to attack by other pathogens such as fungi and can cause the plants to be more prone to heat-related stress. Some of the most common plant pathogenic nematodes we find in putting greens in the southern U.S. include lance (Hoplolaimus spp.), ring (Cricinemella sp.), spiral (Helicotylenchus sp.), stunt (Tylenchorhynchus spp.), sting (Belonolaimus spp.), sheath (Hemicycliophora spp.), and root knot (Meloidogyne spp.). Female nematodes can lay many eggs (up to 500 eggs), which in turn hatch into juveniles. These juveniles will then mature through a series of four molts then becoming adults. Nematodes are motile in the soil for very short distances. Long distance spread occurs through surface water runoff and movement of infested soil from location to location. In non-tilled soil environments such as on a golf course, movement of infested sod is a primary method of dispersal. Generally speaking, sandy soils are more likely to have nematode problems than soils with a high clay content. Therefore, sand-based putting greens are a great environment for nematodes to flourish.

Above ground symptoms of nematode induced diseases will often resemble drought stress, general lack of vigor and little to no response to irrigation, fertilization or even fungicide applications. Symptom expression is directly related to the number of feeding nematodes. Nematode populations can increase very quickly in the summer months. The length of the nematode life cycle is partially regulated by temperature. As temperature increases, life cycles get shorter and the population of nematodes can increases at a faster rate. In addition, if we consider creeping bentgrass plants, as the heat increases, root and shoot growth can slow or stop. If roots have stopped growing (and maybe dying) due to high temperatures and there is a lot of nematode feeding, it is easy to see how creeping bentgrass plants can die very quickly without much warning. Further complicating matters, is the presence of multiple groups (genera) of plant pathogenic nematodes, which can have a synergistic effect on disease severity and symptom expression. The best way to confirm a nematode problem on a stand of creeping bentgrass is to have a soil sample evaluated. These assays are usually expressed in numbers of individuals of different nematode genera per volume of soil. Various treatment threshold numbers have been established for some nematode genera on certain turfgrass types.

Management options:
Few chemical fumigants/nematicides exist as options for controlling plant pathogenic nematodes. Therefore, superintendents should practice methods to promote a vigorous root system on creeping bentgrass plants in the spring before stressful growing conditions prevail in the summer months. I have written before about managing nematode-induced stress. However I will reiterate here. Cultural management should include raising mowing heights (.160 in. or more would be advised), adjustment of the frequency of mowing and rolling to reduce the amount of stress applied to the turf stand, and continued frequent, light applications of fertilizer and water are recommended. Any practice that reduces stress and damage to turf plants will assist the plants in surviving the additional damage that nematode feeding causes. Regular soil assays should be done if nematode activity is suspected.

Dr. Nathan Walker and myself have various experimental chemical treatments that we are evaluating for efficacy toward nematodes. In future posts I hope to comment and show some data. Hopefully we will have something positive to present. Until next time…

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.

Dr. Vincelli's Chemical Control of Turfgrass Diseases

For those of you who have not yet seen this reference from Dr. Paul Vincelli at the University of Kentucky, you will be excited about this post. Dr. Vincelli has been pulling data from the Plant Disease Management Reports (formerly F&N Tests) for a number of years and he continues to update this reference each year. I have to say that it is one of the best references available that continues to provide current fungicide recommendations based on field research conducted throughout the United States.

Access the original Chemical Control of Turfgrass Diseases 2011 here. (current disease update below)

Vincelli Fungicide Chart


Update on diseases this week:
Brown patch and Pythium blight are very active in the mid-Atlantic and northeastern US at the moment as would be expected. Anthracnose also appears to be making some inroads on annual bluegrass putting greens. A big decision has been whether to apply the DMI fungicide tebuconazole (Torque, QP-Tebuconazole, others?) during the summer heat. This has consistently been one of the most effective anthracnose products in trials throughout the US. In our trials this year, we have not had any significant injury or regulation from repeated applications of tebuconazole, but I will note that our site is not as hot as others in the region AND we are not applying any growth regulators in our trial area. I don't have an answer as to whether you should apply it or not, but I guess it would depend on how much Poa you have, how healthy your greens currently are, and how bad your anthracnose is.

Lots o' Heat and Brown Patch

Well it looks like most of the country is in the grip of this heat wave now. We are working on day 29 of days over 100 F for 2011. According to the Oklahoma Climatological Survey map, we average approximately 15 days per year over 100 F. Our record is 50 days and we haven't even made it to August when we typically have our "hot and dry" weather. So….it is going to be a tough summer season again this year.

In our diagnostic lab we are getting a lot of creeping bentgrass samples with high nematode populations and/or suffering from good old summer stress symptoms. I predict that these issues are going to persist for us for the near future and putting greens will continue to become increasingly stressed. Remember, if you have that “big tournament” coming up and the membership is asking how fast they will be rolling, remind them to expect slow. The last thing you want to do during the weather we are having is try to make the greens roll ultra fast and throw a bunch of traffic on them when it is 105 F and the wind is blowing 25 mph! Again I say slow greens are better than no greens. Hopefully everyone has their smooth rollers on and they have reduced mowing as much as they can to manage plant stress. Be sure to have a good preventative fungicide program in place for Pythium diseases and brown patch.

Speaking of brown patch, we have a pretty good epidemic going on most of our research putting greens at the Turfgrass Research Center in Stillwater. Last week we had several evenings that we had humidity above 85%. For the entire month of July we have not dropped below 72 F at night in Stillwater. These conditions have been perfect for brown patch development. As most of you already know, preventative fungicide programs are the best strategy for managing the problem. So what is a good program for the Oklahoma area? Well, each year we conduct various dollar spot and brown patch trials on creeping bentgrass putting greens. These programs are often elaborate and often not cheap! Here are some brown patch data from our 2010 program trials. These trials were on a 'Penncross' putting green with a USGA sand/peat base located at our Turfgrass Research Center in Stillwater. Brown patch data were most severe on the July 16 rating, so I'll focus on that rating and on only the products applied up to that rating. You will find the products and the application dates in the table. Note that all applications were on a 14-day interval. For good control of both dollar spot and brown patch we don't recommend stretching your fungicide interval much past 14 days in our neck of the woods. Also, the DS ADVISORY treatment was an experimental exercise where we were targeting control of only dollar spot by advising sprays using a statistical model. Therefore, no brown patch products were applied resulting in high levels of brown patch.

So what happened? Well, highest levels of brown patch were recorded in the non-treated check plots with an average of 60% of the plot area symptomatic. Somewhat lower levels of brown patch were recorded in plots treated according to the ADVISORY program, but remember this program really doesn’t count when we are talking about brown patch control. All other plots treated with fungicide had significantly lower levels of brown patch and were not different from each other. Although, the OSU2 program had the lowest levels of brown patch (5% severity). Average turfgrass quality was lowest in plots not treated with fungicide and was considered unacceptable. Marginally higher levels of quality were recorded in plots treated by the ADVISORY. All other plots treated with fungicide had the acceptable levels of quality, however, the BASF1 and BAYER1 programs were a bit lower than the others. No symptoms of phytotoxicity were observed. So what this demonstrates is that if you start off with a good preventative fungicide program and make a reasonable decision about the products relative to the pathogens you expect to control, you will be reasonably successful at managing a disease like brown patch.

How do you prepare for the weather?

First, I'd like to welcome Maria Tomaso-Peterson to the blog. She posted the other day and you can catch it here if you missed it.

It's been a while since I have sat down and looked at the weather since I've been traveling, but I got a quick glimpse of what Megan, Jim, and Damon were referring to when I looked at the forecast for this upcoming week. According to weather.com's 5-day forecast, temps are going to peak Thursday through Saturday and everyone from Washington, D.C. along the coast and up to Boston are going to be hit with temperatures in the high 90's to over 100.

As we move into the heart of the summer, we have to watch out for the typical diseases such as brown patch, summer patch, Pythium and the like. After a good lesson that many golf course superintendents had last summer regarding how much their turf can be pushed and perhaps what to do to prepare, I decided to call out to those on twitter to ask the following:

"...how are you preparing for the upcoming weather. 140 or less."  

(for those of you losers not on twitter, '140 or less' refers to the number of characters you can type).  

 

As you can see from some of the posts, people find different things important, but a few things that stood out to me included the importance of irrigation, communication, and maybe a little prayer. Thanks to the following twits for helping (sorry if I missed yours): Greg Shaffer, Mike Jones, Bob Porter, Sam Green, and Ryan Cummings. If you're on twitter, be sure to follow these turfers.

Leave in the comments anything else YOU can add to the list of preparations prior to a major heat wave!

Regional Updates:
USGA Northeastern Update
USGA Mid-Atlantic Update

Weather forecast video

Greetings from the hot, humid, and dry Deep South!

Greetings from the Deep South! I am Maria Tomaso-Peterson, Ph.D and come to you from Mississippi State University where I conduct research and teaching in turfgrass pathology. I am very pleased to be invited by my fellow turfgrass pathologists and bloggers to participate in sharing insights from the Gulf Coast States.

The first half of 2011 has been coined the year of extremes…….. no, I am not referring to politics, but to weather conditions across the United States! South of the Interstate 10 corridor, rainfall deficits are making their way into the record books. Our fellow superintendents in Texas are experiencing the driest seven months on record. When I visited New Orleans, LA in May, I was amazed at the drought stress exhibited by the palm trees along Canal St. South Mississippi and Alabama, as well as the panhandle of Florida (the whole state, actually) are well below average for annual rainfall.

With that, fungal disease pressure has not been the issue thus far. The primary challenge is delivering adequate water to keep the turf alive. Of course, the greens are the primary receivers of irrigation, followed by tee boxes, and fairways (sparingly). The roughs have gone dormant, but not to worry, the bermudagrass will be back! Despite the dry conditions, there are still some pest issues that have to be managed. I thought I would share some of those issues with you in my inaugural blog post.

My fellow turf pathologist out of Oklahoma State University, Dr. Damon Smith, had an excellent review on nematodes in creeping bentgrass back in June. As we know, sand-based putting greens are an ideal environment for plant parasitic nematodes; couple that with root zone temperatures above 65 F for the better part of a growing season in the South, one can see how nematode populations can get out of control in one growing season. Sting and root knot nematodes are the most common species identified from dwarf and ultradwarf bermudagrass putting greens. At the Mississippi State University Nematology Laboratory, analysis results have shown bermudagrass green samples with sting in excess of 500 per 100 cc soil and other samples with root knot greater than 1,200 per 100 cc soil. The affected areas of a bermudagrass green may appear light green to yellow, thin turf density, reduced clippings, and the turf does not respond to nitrogen or irrigation. The damage may be widespread but more often observed in clusters. Symptoms of sting damage on bermudagrass roots (left) include root-pruning and necrotic lesions. Root knot galls are easily detected under a stereomicroscope.

In the photos below, root knot galls can be seen in bermudagrass roots (left) as well as pearly-white, mature female root knot nematodes embedded in a bermudagrass root (right).

For those who stock-piled Nemacur, spot treatment is recommended for control. Curfew® is a soil fumigant which requires a custom applicator and is labeled for use in Mississippi, Alabama, and Florida. Curfew has been granted a 24(c) label from EPA for use on golf courses in Texas and Louisiana. Non-fumigant products, some biologically-based, are also commercially available for nematode control.

Another pest that has been active on drought-stressed turf is the bermudagrass mite (BGM), Eriophyes cynodoniensis, which can be found wherever bermudagrass is grown throughout the United States. Mite injury is most severe to bermudagrass during hot and dry conditions such as those experienced this growing season.

The BGM feeds underneath the leaf sheath. Once feeding commences the leaf tips turn yellow and the leaves become twisted. The internodes shorten resulting in a rosette or witch’s broom appearance. Under severe outbreaks, large areas of turf turn yellow, thin out and may die as a result.

Insect damage was observed on bermudagrass fairways and roughs earlier this month in Texas. When infestations are high enough to cause obvious symptoms of BGM damage, it is necessary to irrigate the affected turf to minimize damage to the plants. Insecticides are available for BGM control; however repeat applications are necessary to reduce the populations.

Several locales along the Gulf Coast have received rain over the past week. These localized rain events are a welcome sign for those folks in the drought-stricken regions. The rains drive up the humidity in the turf canopy which in turn is favorable for disease development. I will be scouting the Deep South for disease outbreaks so I can report back to the Turfgrass Disease Blog in the near future. In the meantime, just remember…..never underestimate the power of a fungus!

Summer stress and diseases

HOT HOT HOT

We've been cooking over the past week.

We are not as bad as Oklahoma. Just reading Damon's post made me break into a sweat, both with the thought of those high temperatures AND the thought of the number of samples he's dealing with. It hasn't been quite that extreme just a bit north, where I am located. But, this current week has been nasty, with more 100+ on the way.

Localized dry spot:

This photo was sent in with a subject line that said “Help!!!”

While I am not a fan of diagnosing based only by photo, the pattern made me suspect localized dry spot (hydrophobic soils) and I suggested that they do the “droplet test” which is described HERE. Indeed, that was the problem. A wetting agent will be useful, but unfortunately the turf itself will not be able to recover very well until these extreme temperatures go away… and that could take awhile.

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Brown patch in creeping bentgrass:

Hot and humid, with high night-time lows = optimal conditions for brown patch. It’s active in greens, fairways, and lawns (fescue).

Dollar spot, in an unsprayed fairway area (creeping bent)

I've also seen some anthracnose in the past few days.

Heat Wave Forecasted for Next Week

We have seen relatively few disease issues in the TDL the past month or so. Throughout Upper Midwest temperatures have been warm, but we have also been quite dry. However the forecast for next week is very different. Highs for next week will been in the low to mid-ninties, more importantly night time temperatures will exceed 72 for most of next week. I included a 7-day forecast from NBC 15 here in Madison, but areas west and south of us will likely experience even hotter temperatures. I know that doesn't compare with the excruciating heat experienced by those in the Southeast and Central US, but the forecast is significant for the Upper Midwest. Especially considering that many courses have substantial Poa annua populations.

IF YOU haven't done so already, this weekend or early next week is a great time to protect your plants against brown patch and Pythium blight. Environmental conditions next week will be ripe for these two diseases. Moreover, anthracnose, dollar spot, summer patch and leaf spot could also flare up depending on where you are with fungicide applications. I mention leaf spot because we have been dealing with a Bipolaris leaf spot in the Midwest for two or three years that does not respond well to applications of iprodione. This disease also remains active throughout the summer months and has been problematic primarily for older golf courses. The disease tends to be more severe on certain clones of older creeping bentgrass fairways causing a "splotchy" reddish appearance to fairways. It does not manifest into distinct symptom. An image of typical stand symptoms is below.

Last year we initiated a fungicide trial at a course in Wisconsin to investigate chemical control options and found that Heritage TL, Insignia and a tank mixture of Chipco 26GT and Daconil Ultrex suppressed symptoms when compared to the non-treated control. Chipco 26GT by itself did not suppress the symptoms, indicating that Daconil Ultrex was more effective in controlling this disease. Note that I use the word suppress we have not been able to prevent the development of this disease, only suppress the symptoms. Here is the report from last year's trial. This has been a difficult disease to work with because it only seems to affect certain clones. Thus it took some time to figure out how to rate it.

Some other things to consider for next week: limit mowing by alternating mowing and rolling, skip clean-up passes, raise the mowing height and absolutely avoid applications of DMI fungicides to putting greens.

The Heat is On!

You “Beverly Hills Cop” fans will recognize that title from the soundtrack of the 1984 hit movie that Eddie Murphy starred in. This song also seems appropriate for much of the mid-west and southern plains, as the number of turfgrass samples coming in to the OSU Turfgrass Diagnostic Laboratory has increased over the last several weeks. Obviously, the spring and summer growing seasons are typical periods when diseases of various turfgrass species are of most concern. Currently, most of the samples arriving in the laboratory are cool-season turfgrass species (fescue and creeping bentgrass). Many of the submitted samples are suffering from summer-heat related stress and are in general decline. Remember that cool-season grasses, especially fescue and creeping bentgrass grow best during the cooler seasons. When ambient air temperatures become hot (90 F+), growth of these grasses will dramatically slow or stop and can go into rapid decline. Root growth of cool-season grasses will cease when soil temperatures are above 80 F.

Currently, the average 2-inch under-sod soil temperatures for much of Oklahoma are in the low-to-mid 80s according to the Oklahoma Mesonet weather station network. In Stillwater, we are averaging around 90 F. Thus, root growth on cool-season grasses is not occurring. Research has also shown that as air and soil temperatures rise above 90 F roots will start to die. With high temperatures yesterday (June 10) in the triple digits and low temperatures not falling below 70 F (except for the pan handle) throughout Oklahoma, root mortality on cool-season grasses is going to be common in the coming days. For some areas the situation has been made worse due to prolonged drought and early onset of heat. According to the Oklahoma Climatological Survey, the month of June was the 2^nd warmest and 4^th driest on record since 1895. We have an average statewide precipitation deficit of 3.08 inches. 

Turfgrass plants that entered summer without a sufficient root system are more likely to not sustain growth, turn yellow or brown and go into general decline (see images). Symptoms of decline can resemble diseases caused by pathogens. Patch symptoms due to summer stress may look much like take-all patch. Turf can appear off color or golden brown and in areas where the plant stand is thin algae formation is common (see images). When roots are examined no evidence of the pathogens that cause these patch diseases are typically present. While evidence of root inhabiting fungi will often be noted, many of these fungi are simply naturally occurring root-inhabiting organisms that are not pathogenic. Also beware that while it may appear to the naked eye that the grass plant has deep or healthy roots this may not be the case. The vascular portion of the root is resistant to decay and may appear to be healthy when in fact it is dead.

To manage summer stress we are recommending good water and fertility management. Where appropriate, water very deeply and as infrequently as possible, while hand watering “hot spots”. ”Spoon feeding” may be necessary to sustain turf until temperatures are more favorable for cool-season grasses. Avoid damaging activities such as dethatching, aerifying, and any other management technique that can cause injury to turfgrass until it is again actively growing. A fungicide (such as Fore or Daconil) may need to be applied to keep algae formation under control on areas devoid of grass. Also, mowing heights should be raised. When the membership complains about slow greens, remind them that playing on slow greens might be better than playing on no greens.

Weather conditions in general have been too hot and dry for most turf pathogens. However, we did have one case of Pythium blight on a putting green where a severe case of scalping occurred and excessive irrigation was applied for multiple days. This resulted in an excessively wet environment that favored Pythium development. We also have observed brown patch on our research putting greens in Stillwater. Brown patch epidemics began this weekend and have increased over the last day or so.

Hopefully the heat will pass soon and we will have a nice cool August. Hey, stranger things have happened…