Dead Bentgrass Makes Headlines

Well, you know things are rough when the local media is writing about Pythium, aerification, and MiniVerde bermudagrass. Unfortunately that's where we are here in North Carolina and many other parts of the southeast. Check out the following article from last Thursday's Charlotte Observer: 


Hot Weather Turning Putting Greens to Toast


Overall, I think its a pretty accurate description of the struggles that golf courses are facing in the region. I'd be curious to hear everyone's thoughts. There are also a couple of factual errors in the article. I'll give a prize to the first people to point them out by leaving a comment on this post!


A lot of people have been asking about converting their greens to ultradwarf bermudagrasses. They are definitely a good option in certain situations, and several courses in the area have made the switch with great success.


My only advice is this: if you can't maintain good bentgrass greens because of problems with shade, air movement, or soil drainage, then you won't be able to maintain good bermudagrass greens either. The courses that have been most successful in converting to ultradwarfs also removed trees, improved air movement, and corrected drainage problems. Who knows, maybe bentgrass would be doing just fine with these improved growing conditions?

Summer Stress Programs for Desert Bentgrass in CA

Developing a Summer Stress Fungicide Program for Coachella Bentgrass (and the Case of the Mysterious #13)

This is a follow up on something I been meaning to address but spurred on by an email I received this week:

Dr. Wong,

I am a Golf Course Superintendent in the Palm Springs area and manage Penncross putting greens. As we both know, heat and cool-season grasses don’t work well together.

Currently we are experiencing exceptional summer bentgrass decline due to high heat and humidity. Are there any fungicide trials or protocols that other Superintendents may be using to minimize effects of SBD? We have fans on each greens, and water as needed with syringing during the day. Our heights are .150 and mowed every other day. Other than that we try to keep them alive.

Hot in Coachella

Yes, bentgrass and triple digit temperatures through the summer get along as well as Meg Whitman and Jerry Brown in California. Based on work done at NC State by Turfgrass Specialist Art Bruneau, cool season turfgrass growth pretty much declines rapidly when 4-inch deep soil temperatures reach 70°F with root and shoot growth completely shutting down at 77ºF and 90ºF, respectively.

http://www.turffiles.ncsu.edu/articles/tf00766.aspx

With soil temps in the California desert hitting 70 to 90ºF from April to September, it means a long late spring through the fall of tough conditions for superintendents in the desert (including other areas in the SW like Arizona, New Mexico and Nevada) who have to hold onto their bentgrass year round.

Although fighting Mother Nature through this period can be partially successful using fans and syringing; in any case, simply put the high temperatures will result in poor growth and recovery from the bentgrass magnifying any damage caused to the turf by mechanical, environmental or pest stress.

From a pathologist’s point of view, the diseases that would likely cause the most damage to bentgrass in this climate would be takeall patch, Pythium blight , Curvularia blight and algae.

Month	Avg. Hi	Avg. Low	Avg. Prec.
Jan	70°F	44°F	1.27 in.
Feb	75°F	47°F	1.15 in.
Mar	80°F	51°F	0.63 in.
Apr	88°F	56°F	0.08 in.
May	95°F	63°F	0.06 in.
Jun	104°F	70°F	0.05 in.
Jul	108°F	76°F	0.19 in.
Aug	107°F	76°F	0.40 in.
Sep	101°F	71°F	0.39 in.
Oct	91°F	61°F	0.11 in.
Nov	78°F	50°F	0.29 in.
Dec	70°F	43°F	0.61 in.

Take all typically infects and damages plants in cool wet weather through the fall and winter. Symptoms can often show up under periods of heat stress because plants with damaged roots simply can’t efficiently use water to keep themselves alive. In the desert, the high temps really hamper the ability of the turfgrass to recover and regrow, magnifying take all damage on bentgrass greens. I won’t cover it much here, but soil pH and manganese management coupled with preventive fall fungicide applications work best for preventing problems with take all.

Pythium blight is a real threat to cool season turfgrass when night time temperatures stay above 68ºF and there’s adequate moisture to trigger fungal growth and spread. There’s an excellent review of Pythium here at the Rutgers website:

http://www.turf.rutgers.edu/research/diseasecontrolseminar/pythium.pdf

Believe it or not, but Curvularia blight is pretty common to find on bentgrass coming from the desert. Curvularia can often be considered a wimpy disease that only attacks weakened or nearly dead bentgrass, but like anthracnoseon Poa, it can be the nail that closes the coffin on your summer stressed bentgrass if not controlled.

Alage can also turn up commonly as it’s quick to colonize wet surfaces and thinned out bentgrass in the summer.

The Mysterious Program #13

As detailed in the Pythium presentation above, Bruce Martin at Clemson is credited with developing a fungicide spray program (#13) that has worked very well for managing diseases on creeping bentgrass in the southeastern U.S.: http://www.usga.org/course_care/regional_updates/regional_reports/southeast/Program--13-Still-The-Best-At-Dr--Martin-Fungicide-Trials---December-2008/

The question posed by several Coachella Valley superintendents has been “how well does #13 work in California?”

Well, Bruce’s #13 provides broad spectrum protection vs. a number of summer diseases while using some of Bayer’s “Stress Gard” pigmented materials, and Insignia which BASF is reporting to promote plant health. But….the southeast gets a lot more humidity and #13 is also designed to pick up brown patch and dollar spot; it’s just too dry in Coachella to have these figure as major players in a summer disease profile.

Looking at #13, applications start in late May in the southeast and go at 14-day intervals; here’s the break down with likely targets of activity.

May 22: Tartan 2.0 fl oz --> brown patch/dollar spot control

June 5: Insignia 0.9 oz --> broad spectrum disease control

June 19: Spectro 90 5.76 oz --> broad spectrum disease control (no Pythium actvity)

July 3: Signature 4.0 oz + Daconil Ultrex 3.2 oz --> Pythium control, algae control, stress reduction

July 17: Insignia 0.9 oz --> broad spectrum disease control

July 31: Signature 4.0 oz + Daconil Ultrex 3.2 oz --> Pythium control, algae control, stress reduction

August 14: Chipco 26GT 4.0 fl oz --> brown patch/dollar spot/Curvularia control

August 28: Tartan 2.0 fl oz --> brown patch/dollar spot control

OK – if you discount the presence of dollar spot and brown patch in Coachella, you can see some of these applications would not be necessarily applicable. Also with regard to Tartan which is a mix of Compass and Bayleton, applying a DMI (Bayleton) isn’t necessary, especially if dollar spot pressure is absent. Spectro probably isn’t needed as much, again due to the lack of dollar spot and brown patch pressure.

Pythium pressure is likely to come from June through September with high night time temperatures. Insignia and Signature + Daconil applications would probably give some significant benefits during this time for both Pythium and “plant health benefits”. Although other Pythium-specific fungicides like Subdue, Banol and Stellar could be used, I would save these for overseeding type situations or when you know that hot wet weather is coming. Otherwise, it may be fine to rely on preventive applications of Signature or other phosphonate/phosphite type products during the summer. Although many of the phosphonate or phosphite type products do a very good job of controlling pythium and improving plant health, the “Stress Gard” pigment in Signature is something I think works pretty well as an added layer of stress relief for your turf.

I’d see Curvularia as a constant threat through the season, but it may not be worth using a 26GT application specifically for this disease, when you can get control with other materials.

A contact fungicide like mancozeb (Fore) may work just fine in Coachella for keeping pathogens like Curvularia at bay, plus beating back algae.

So…in putting all of this together, I’d say that #13 is a great program, but not necessarily well fit for southwestern desert bentgrass greens.

Looking at the situation, maybe something like this would work:

May 15: Fore 8 oz

Jun 1: Insignia 0.9 oz

Jun 15: Fore 8 oz

Jul 1: Signature 4.0 oz + Daconil Ultrex 3.2 oz

Jul 15: Insignia 0.9 oz

Aug 1: Signature 4.0 oz + Daconil Ultrex 3.2 oz

Aug 15: Fore 8 oz

Sep 1: Signature 4.0 oz + Daconil Ultrex 3.2 oz

Sep 15: Fore 8 oz

Keeping the Signature and Daconil in the mix as a stress & algae application; Insignia as a 28-day preventive early in the summer and regular applications of Fore to clean up algae and clean up “junk” diseases like Curvularia may work just fine.

I’d like to see some research in Coachella to support the suggestions, but this type of program may be a good starting point. If you think "there goes Dr. Wong, smoking the crack again." - that's fine too; I think it's good to have some discussion about what is working for guys in the desert who are growing bentgrass.

Bottom line: programs like #13, are very good, but may not cover the diseases & stresses unique to the southwest – think about what you’re trying to fight and design a program around that.

A Few Thoughts about Nematodes

One thing that needs some attention as far as bentgrass greens in Coachella is the presence of some new root knot nemtaodes found affecting cool season turf. Very high populations were associated with severe damage at a few locations in Coachella in 2009. As discussed above, the summer stress for growing creeping bentgrass in Coachella is already pretty high – nematode populations really need to be considered in this equation.

This is a green from 2009 in Coachella that took some severe nematode damage; don't let this be you!

If you’re growing bentgrass in the Valley; it’d be worth having a test done to see if you need to worry abouyt these critters as well.

OK – until next week – signing off from the Right Coast…..

Just a brief update

It has been tough to give an update since things have been so busy, but I thought that I would at least give a summary of what I have been seeing in the Northeast either while I was in the field or in the lab.

Typical diseases:
Dollar spot, anthracnose, brown patch and Pythium blight have been working on turf for a few weeks.  Gray leaf spot has also been reported by some in the region, although I am not sure if this has been confirmed by any diagnostic lab.  Also, many courses have been either excessively wet or more likely excessively dry.  The dry conditions have been particularly noticeable around the NJ/NY region.  At this point, it is just about keeping things alive and getting through the summer until conditions change to favor turf growth.

All the talk:
For the last few weeks there have been two unusual diseases that are causing a lot of scare around the region.  One is the issue of bacterial wilt potentially being a problem on creeping bentgrass.  This issue is one that is going to take some time to resolve, but I don't think that it is nearly as widespread as many think.  The second issue is the one dealing with what I refer to as Pythium patch.  This is not a defined disease as I have not really had the ability to put a major effort into researching it, but the bottom line is that there seems to be a Pythium that selectively impacts annual bluegrass that is not suppressed by the typical Signature applications. My experience with this problem is that you should continue your Signature applications for the more virulent Pythium species and for summer stress, but you should supplement a more traditional Pythium fungicide into your program during conditions like we are experiencing now.

Field Days:
This is a tough time of the year to visit with your local research institutions since the weather is not cooperating, but remember that you can learn a lot of the latest and greatest in terms of management recommendations by attending these events and talking with the University researchers as well as your peers.  This week will see Field Day's by both UConn (July 21) and UMD (July 22).  In the coming week, Rutgers will also be hosting their field day.  Please make any effort that you can to attend these events if you can get away from your course for the day!

Spray, but watch the burn

With temperatures in the high 90s or even triple digits throughout many parts of the mid-Atlantic and Northeastern United States has many scrambling to protect their turf from potential diseases. In addition to the uncharacteristic high temperatures is equally unusual low relative humidity. One common thing in calls that I received this weekend was that everyone was scrambling with hoses.

Another interesting point that I generally don't think about when applying fungicides for field studies is the potential for burn when spraying. In many trials, we only apply a couple of products at a time and rarely mix to the degree that many golf course superintendents. I always joke at meetings about how the record number of items that one superintendent put in the tank was 23! So in light of this and in light of the fact that many are trying to get that next spray out, I received a couple of questions about potential burn when spraying.

In a past post, Lane spoke about the potential negative impact of some of the DMI's on cool-season turf in the summer. In past trials, we have seen some severe leaf tip burning when certain products are mixed together. One product that has gained in popularity is the various phosphites on the market. In some field work, we found that these products can be "hot" and burning can occur specifically when these are mixed with certain products like the DMI's as well as PGRs. Additional things to consider include the use of wetting agents and other products that can add to the potential for phyto. Please leave us a comment or follow the discussion that I started on the Facebook Page here.

Finally, I received a call from a couple of golf courses this week that were concerned about some uncontrollable summer patch on their greens this week. While summer patch may start to show up in this weather and would be fairly typical for this time of year, I call attention to a post on an unusual Pythium species that I wrote about last year. This is something that is relatively new and little is known about it. I can say that it is a real issues, however, and those of you relying on Signature for your sole Pythium control should read this post!

For those of you that follow the LPGA, check out this week's US Women's Open at Oakmont. I am here in the hotel now and ready to spend the practice rounds with John Zimmer's staff and the USGA. Wake up call tomorrow morning at 3:30AM...I am rooting for Christina Kim who just missed out on a win this past week in a four-way playoff!

Check out these photos from last year's Women's Open at Saucon Valley

Still Wet in the West

Torrey Pines North Course #6 Putting Green (AP Photo/Chris Park)

As posted last week, California got some substantial rain and wind with southern California getting 3 to 5 inches of rain, while norcal got about 3 to 6. For us in the West, that's a lot considering our multi-year drought.

Cool season Pythium popped up in the diagnostic lab as well as rapid blight from socal and Las Vegas, which was a little surprising considering that the rain should have leached some of the sodium out of greens last week. Not surprisingly - pink snow mold was reported in both southern and northern California.

With cool temps in the 50s and 60s and scattered rain expected, we can expect more pink snow mold through out the week.

Although most California superintendents are certainly not facing the winterkill issues that our northern neighbors in Oregon and Washington are facing, annual bluegrass greens in the colder parts of the state can look pretty crappy under these cold weather conditions. Jim Alwine (Stockton Golf and Country Club) has a nice example of this on his blog post here: http://sgccturf.blogspot.com/2010/01/poa-looks-tired.html

Like Jim says, annual bluegrass can look tired and clorotic under these cold weather conditions and just refuse to grow, especially under low fertility conditions.

Trials and Tribulations (but no Tiger) at Torrey Pines
With all of that gorgeous kikuyugrass, sweet Poa greens, and a killer Rueben sandwich at the Grill & Bar, Torrey Pines Golf Course is one of my favorite places in California.

Last week's storms wreaked havoc on the course prior to this week's Farmer's Open (ex-Buick Open). With 4+ inches of rain over 5 days and 20 to 40 mph winds on Wednesday, Director of Golf, Jon Maddern and course superintendents Wayne Carpenter and Candice Combs were faced with some substantial storm damage with just a few days to get the course ready for the tournament.

http://www.10news.com/video/22319497/index.html

According to North Course Superintendent Wayne Carpenter:

We lost roughly 20 trees on the North and the South in this last storm. The soaking rains from this storm and the previous storm combined with the high wind spikes pushed over the surface rooted trees. Most of our trees have rooted on the surface for the water and because the hard sand stone keeps the roots on the surface. Almost all the trees were euc's [eucalyptus]. We only lost a couple of pines of various types. The difficulty in the clean up was all the branches, twigs, and leaves that were down everywhere. That was the tedious hand work. We couldn't do anything but put blowers out to help make piles, rake and pick up everything. The trees were a lot of work for the crew, but at least they were in one place. We could clean it up and move on. The hardest job was pumping out bunkers and restoring the faces with sand. The South lost all the sand in every face on their bunkers. The North had wash outs, but not on the scale of the Souths. I'm sure Candice can better attest to the amount of time and labor this job took on her side, but this took a huge expenditure of our crews resources. We had a number of GREAT volunteers that helped with this task and I would not have finished the North without their help. Our crews have completely worn themselves out getting this place back into shape.

About 40 volunteers, including 15 staff and superintendents from golf nearby courses in the San Diego area, pitched in to help clean up the storm damage. You gotta love that collegiality and camaraderie that's present in this industry and amongst superintendents and their crews. I wonder if the public realizes how much work goes on behind the scenes to get courses ready for the big day, especially when Mother Nature deals you a bum hand.

As you can see from ESPN's coverage of the tournament today, all of that effort from Candice, Wayne and Jon, their crews and volunteers has made for some pretty sweet results:

http://espn.go.com/video/clip?id=4867407&categoryid=null

Let's hope that the rain stays away for the rest of the week so the crew at Torrey can get some well deserved rest!

By the way, Mr. Daly, it looks like you got some gray snow mold in your pants. We got some stuff that can fix that...I'm just sayin'


(AP Photo/Denis Poroy)

Thanks to Matt Marsh (Valencia Country Club) and friends for gettin' that idea in my head.

Signing Off From the Right Coast Until Next Week....

Prevention of Pythium Root Dysfunction in Bentgrass Greens

For golf course superintendents who've struggled with Pythium root dysfunction in the past, now is the ideal time to initiate a preventive fungicide program. Pythium volutum, the most common PRD pathogen in our experience, starts to actively infect bentgrass roots in the fall when soil temperatures consistently dip below 75 degrees. That, combined with plenty of moisture throughout the Southeast, means that the pathogen is almost certainly active now.

Not very many products are effective against PRD. Even though it is caused by a Pythium, some of the standard Pythium fungicides like mefanoxam, propamocarb, ethazole, and fosetyl-Al are not very effective when applied alone.

Instead, the QoI and Qii fungicides have been most effective against PRD in our trials. The QoI fungicide Insignia (0.9 oz) has historically been the most effective product. We have also seen good control from Heritage TL (2 fl oz) and Compass (0.25 oz) but only on a preventive basis.

The QiI class of chemistry is relatively new, and there is currently only one product available in this category: Segway, which contains the active ingredient cyazofamid. Applications of this product at 0.9 fl oz per 1000 sq ft have also provided very good control of PRD. Segway is an important addition to our arsenal against PRD because it gives us another chemical class to rotate with to prevent the development of fungicide resistance in Pythium volutum.

Tank-mixtures of fosetyl-Al + propamocarb (Signature, 4 oz + Banol, 2 fl oz, for example) and fosetyl-Al + mefanoxam (Signature, 4 oz + Subdue Maxx, 1 fl oz, for example) have provided good control in our trials or based on superintendents' observations. These tank-mixtures, although expensive, should also be worked into your program to help prevent fungicide resistance.

As mentioned above, a preventive program should be initiated in the fall when soil temperatures consistently dip below 75 degrees. Repeat applications on 21 to 28 day intervals as long as soil temperatures are between 50 and 75 degrees are recommended where PRD has been a persistent problem. Less frequent applications may be sufficient where the disease has only been a minor problem or where growing/management conditions are less stressful during the summer. Since PRD is a stress-induced disease, there is no "one size fits all" fungicide program to control it.

Note that applications of Insignia and Segway should be watered into the soil immediately to drive the fungicide into the root zone. Approximately 0.125" of irrigation has worked well in our trials. Since fosetyl-Al moves downward in the plant, tank.mixtures including this product should be left to dry on the foliage for best results.

End of the Summer? Says Who?

"Frank, do you know what fire ants look like? Well, you should, because you're standing on top of a whole bunch of them..."
- David Hay, CGCS, Indian Wells Country Club

It's been a long week starting in Monterey at Mike McCullough's Northern California Golf Association's Assistant Superintendent's Boot Camp, leading to Harding Park in San Francisco and culminating in Palm Desert today. To the left, you can see our Pythium trials being conducted in collaboration with Tom Shephard at Desert Falls GC. I'm using indicator dye in my spray tank, so you can see my spray uniformity (or lack of!). Everytime I head to Coachella to do work - I can't help but think about the impromtu lesson on fire ants that I got from David Hay.

As far as Pythium - anytime night time temps are over 68F during the overseed, you're at risk for an outbreak. With night time temps in the 70s for the next few days - definitely watch out for Pythium developing if you are overseeding in the desert this week!

It's the Fall, and it doesn't quite feel like it....
Yes, it's late-September and it's supposed to be cooler, but we're still getting triple digit temps here in parts of California. Anthracnose and summer patch are still active on Poa greens inland, whie rapid blight is coming back in cooler coastal areas.

If you're about to aerify, nitrogen applications at this time should help reduce down both anthracnose and summer patch. Don't hestitate to give greens a healthy shot of N at this time. If you've got lots of anthracnose, a solid fungicide application wouldn't hurt either. If you have lots of active anthracnose now, it could come back to bite you in basal rot form if you go into the winter with weak greens.

Since rapid blight is encouraged by mechanical damage (like top dressing) - make sure to leach salts before aerification. If you've historically been at risk for rapid blight in the early fall, make a Insignia/Compass plus mancozeb soon after aerfication and top dressing on Poa greens.

2009 UCR Field Day
Last Thursday, we held a very succesful field day at UCR with over 160 participants. Thanks to our sponsors Aquatrols, BASF, Bayer Environmental Science, Dow AgroSciences, Green As It Gets, Inc., Grigg Brothers, Gowan Turf & Ornamental, RootGel West, Syngenta Professional Products and Valent Professional Products for helping us with our tent and BBQ lunch!

Turf disease -wise, I got to show off our anthracnose plots and results from 2009 trials which focused mainly on new DMI fungicides. A preliminary report can be found here. Also, we got to discuss results from our spring dollar spot trials. That report can be found here.

Signing off from the Left Coast until next week......

Unusual Pythium on Putting Greens

In last week's post, I briefly mentioned a strange Pythium problem that has shown up over the last few years. A few superintendents in the New York Met and select regions in the mid-Atlantic and Northeast may have heard me speak about this at a local conference, but for the most part this problem is not a widespread problem. I will make this disclaimer: we have very limited information on what is really going on with this Pythium and a majority of our info is from trial and error.

Between 2005 and 2009, a dozen or so golf courses had issues controlling what was believed to be summer patch on their golf course putting greens. I had made trips to several of these courses to confirm that what we were seeing in the lab matched what was happening in the field. As it turned out, field symptoms were typical of the classic characteristics of summer patch. Further investigations in the lab revealed that a Pythium species appeared to be the culprit.

The Pythium was not a root disease, but was instead a foliar problem. While mycelium can be seen in small quantities following incubation, it does not "fluff" out like your typical Pythium bligt. To see the mycelium, you need a hand lens or a dissecting microscope. Two separate Pythium species were routinely isolated from symptomatic samples. Isolates were identified via DNA sequencing and although the Pythium spp are not new to turf, they are considered weak pathogens and generally not associated with severe Pythium infestations.

The weakly aggressive species may be the reason for the types of symptoms in the field. As mentioned, the symptoms of this disease are nearly identical to summer patch. The disease appears to selectively infect annual bluegrass and leaves the bentgrass to "fill into" the center of the declining patches. The patches may show up during late spring and the disease may remain active until late summer. Unlike typical Pythium diseases, the patch symptoms are SLOW to develop. Similarities among the courses that have dealt with this (from Maryland up to Massachusetts) include: 1) native soil putting greens with routine topdressing; 2) limited to no internal drainage, mixed bentgrass/annual bluegrass stands; and 3) reliance on Signature for the summer management of Pythium.

While the preventive applications of Signature have been shown to provide excellent suppression of Pythium blight as well as provide improved summer stress management, its influence on this particular problem remains unknown. In discussions with a colleague at the University of Florida, it appears that while Signature provides excellent suppression of the typical, more aggressive Pythium species, in vitro tests have shown reduced effectiveness on certain species (at least one of which are those isolated from our samples).

So what do you do about this potential problem?

1. Get samples diagnosed: This is not an easy one to diagnose and takes a little extra effort. Symptoms look identical to summer patch, which makes accurate identification even more difficult.

2. Utilize more traditional Pythium fungicides during summer: My recommendation has been to stay on your Signature program (or get on one) throughout the season to enhance your summer stress management. However, DO NOT RELY on these applications exclusively to suppress Pythium. My recommendations have been the preventive applications of something like Subdue or Segway when temperatures start to become conducive for Pythium.

3. Curative control with Banol: There have been limited to no trials for this disease on putting greens (if anyone is willing to have me create a quilt-patch of healthy and dead turf on their putting green, please let me know). What seems to work consistently for the curative control of this disease, however, is the foliar application of Banol. Do not water this in.

4. Improve Drainage: This is more of a long-term solution, but anything that can be done to improve the internal drainage on the putting green will help in managing not only this disease, but various other problems during the summer.

Remember, there is very limited research-based information on this problem. We will continue to monitor new cases closely, but unfortunately don't have any real answers at this point (although the control measures mentioned above have been effective). If you think that you may have (or had) this problem, feel free to let us know in the comments or via email.

**I will try to find some images to post tomorrow, but wanted to get this out on-time today.

lower temps, lower moisture

We often say, “it isn’t the heat, it’s the humidity.” Indeed, humidity can be a measure of how nasty it feels outside. However, I also like to use dew point. See, hotter air can hold more water. For example, at 90 degrees F, relative humidity of 62% might not sound so bad. But, the dew point is 75. That is, there is so much moisture in the air that the temperature only needs to fall to 75 for condensation to occur. Dew points above 70 are very uncomfortable. Check out “dew point” on wikipedia and you’ll find more details and a better explanation.


On Tuesday evening the dewpoint here in Manhattan, KS, was 77, and I think that is the worst I have ever experienced.


But, the weather has changed and in many areas we are experiencing some relief, with highs in the low/mid 80’s and lows in the upper 50’s (!!) and low 60’s for the next few days.


Brown patch that was highly visible on putting greens on Tuesday and Wednesday is already fading. The image was taken by my colleague, Dr. Rodney St. John, and it’s my favorite photo ever of brown patch in greens-height turf.

With the temperature change, dollar spot that had been suppressed in the heat is now creeping back in.


Earlier in the week I received a couple more samples of Pythium from fairway height perennial ryegrass. The change in temperatures will help reduce disease pressure. In addition the break in temperatures will allow some cultural practices that superintendents might have been holding back on during the hot conditions.

Stress & 'todes

It’s always hard to follow Frank’s posts. I mean, what can I write after he applies “If it’s yellow, let it mellow” to turf disease?

The big concerns lately have been brown patch, foliar Pythium, stress, and nematodes.

While brown patch seems to have decreased somewhat from our surprise late June epidemic, I suspect that it will come surging back in with our forecasts of more heat, humidity, and rain.

Dollar spot has totally disappeared from our research plots. Too hot!

As for foliar Pythium, the rains keep coming, nighttime lows remain high, and the sites with the disease are on high alert. Most have put down one or more applications of a Pythium fungicide and are watching for new activity.

Stress? That is on the plate every week. In some recent samples, waterlogged soils have clearly caused root decline with some secondary Pythium nibbling on the aftermath. We still can’t seem to dry out in some areas.

The photo illustrates a stress problem where greens received a little too much N, got puffy, then scalped. You can see the scalped spots right at the edge where the mower hit the green.

Nematodes in turf are a tricky subject. There was a lot of discussion earlier this week amongst turf pathologists about damage thresholds in nematodes. Damage thresholds are hard to pin down, and the potential damage of a certain population of nematodes varies with the overall amount of stress at the site. Sometimes there is a correlation between turf damage and nematodes; often there is not. Usually there are multiple factors in play.

One nematode that is pretty well documented to cause damage even at low numbers is sting nematode. We picked up sting in a sample a few days ago. I heard Dr. Mike Fidanza (Penn State) joke one time, “If you want to spread news, what are the 3 best ways to do it? 1) Telephone. 2) Telegraph. 3) Tell-a-superintendent.” That is, news travels fast in this industry. After the sting finding, we had a sudden flush of requests for nematode testing because the word had gotten out. Numbers of all plant pathogenic nematodes were pretty low, and no sting nemas were detected anywhere else.

It's not too late to prevent fairy ring and Pythium root dysfunction

If you haven't made your preventative fungicide applications for fairy ring and Pythium root dysfunction yet, it's not too late, but it will be very soon.

Although symptoms of these diseases are most common during the heat of summer, we've found that the pathogens are most active during the spring and early summer. Fungicides are most effective when applied during these periods of pathogen activity.

Pythium root dysfunction is a common problem in the southeast on creeping bentgrass putting greens built within the last 10 years. The pathogen infects the roots during the fall, winter, and spring when soil temperatures are between 50 and 75 degrees.

Remember that Pythium root dysfunction is a stress-induced disease. Low nitrogen inputs (less than 3 lbs per year), drought stress, close mowing, and infrequent aerification are common sources of stress that compound the disease. Maintaining a healthy turf plant with sound agronomic practices goes a long way towards reducing problems. All the fungicides in the world will not provide acceptable control of PRD if the turf is continuously stressed.

Preventive fungicide applications should be made in the fall, winter, and spring when average daily soil temperatures between 50 and 75 degrees. For details on recommended fungicide rotations, please refer to our information sheet on TurfFiles. Remember that fungicides should be watered into the soil right away for best results.

We've made excellent progress in fairy ring management over the last 5 years. The DMI fungicides, such as Bayleton, Eagle, Tourney, Trinity, and Triton, have been providing excellent control in the southeastern United States. For best results, these products should be applied when 5-day average soil temperatures are between 55 and 65 degrees. However, as long as they are applied before symptoms appear, they will provide good control in our experience.

Just like with PRD, fungicides must be applied to the soil for best results. Applications should be watered-in as soon as possible with 1/8" to 1/4" of irrigation. We do not recommend tank-mixing the DMIs with wetting agents or soil surfactants, as we've observed reduced control from these combinations. Wetting agents should be applied separately as part of your normal program.

For more information on fairy ring prevention, please refer to the Fairy Ring Disease Profile on TurfFiles.