Microdochium Diagnosis: It's Magically Delicious!

Playing off of John's previous post about knowing his Lucky Charms, I thought it would be great to highlight some differences between leaf spots and Microdochium patch. We have seen a lot Microdochium patch throughout Wisconsin. Most likely because the weather has been cool and wet. Before we talk about John's Lucky Charms comment, I think we better discuss the symptoms we have seen.

This time of year Microdochium patch symptoms on creeping bentgrass/annual bluegrass swards are typically water-soaked in the center of the patch with the perimeter of the patch exhibiting chlorosis. Patches this time of year typically range from 3 to 12 inches in diameter. The former name of this disease was pink snow mold. This was a bad name because snow is not required for disease development and the patches are not always pink. This is evident in the picture in the upper left corner of this post. The picture demonstrates the water-soaking in the center of the patch surrounded by chlorotic plants. You'll also notice the abundance of mycelium on the leaves, this is typical of Microdochium patch after incubation. Mycelium production can also occur in the field

Microscopic examination of the leaves coated in mycelium will reveal the crescent moon shaped spores. The spores have a prominent middle septation and lack a foot cell typical of Fusarium species. The second picture in this post represents typical Microdochium nivale spores. John, I loved your analogy of Lucky Charms for describing Microdochium spores. After Damon Smith mentioned the analogy to me, I used it to explain Microdochium to my graduate student. The one problem, he's from China and doesn't know what Lucky Charms are!



We also had a few leaf spot samples come through the clinic. We did not have red leaf spot, but the symptoms are fairly different from Microdochium patch. These symptoms are somewhat similar to what John described, irregular patches that have a reddish, brown tint. The samples that came through our clinic were induced by Bipolairs sorokinana most likely. The transition from last week to this week was fairly dramatic. The previous week was warm and this week the temperatures plummeted. Tonight there is a Freeze/Frost warning for Northern Wisconsin and the Upper Peninsula of Michigan. So we quickly transitioned from summer to fall!



The spores of leaf spot fungi are quite different. The spores are humongous compared to Microdochium spores, have a brown tint and have 6 to 10 septations.

Many golf course superintendents are making a fall application of vincozolin and chlorothalonil or iprodione and chlorothalonil to clean up any late season dollar spot and outbreaks of Microdochium patch. These are good combos for Microdochium and should provide good control until snow mold applications are made. Thiophanate-methyl is fairly effective against Microdochium as well.

Large patch is brewing in the warm-season grasses

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

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

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

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

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

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

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

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

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

some dollar spot info, and another new tree disease

It is hard to believe that there are only a few more days in September.

It is pretty quiet on the disease front. Dollar spot and large patch are the major issues.

First, I have to correct a typo from last time. I had listed a dollar spot fungicide treatment with Trinity as 0.1 oz/1000 and in fact it was 1.0. Apologies for any confusion.

Posted below are treatments from another dollar spot study that was conducted in a stand of A4 at our research center in Manhattan. I had a figure ready to go, pasted it, but then when I actually uploaded it turned to gibberish. Then, did it again. So I'll just type in a summary of the information:

All treatments were applied on a 14-day interval at 2 gal/1000


TREATMENTS & OZ/1000
1) untreated
2) Triton Flo, 0.5
3) Triton Flo, 0.75
4) Triton Flo, 1.0
5) Banner Maxx, 2.0
6) Reserve, 2.8
7) Reserve, 3.2
8) Reserve, 3.6
9) Reserve, 4.5
10) Concert, 5.0

On August 27 and Sept 10 the % dollar spot in the untreated plots was 9 and 15%, respectively. On Aug 27th, all the fungicides held dollar spot to zero. On 10 September, Banner Maxx, Concert, and Reserve at the 3.6 oz rate held dollar spot to zero, and the others all had just traces of disease, no more than 1% plot damage.


New disease on black walnut:

I know this is a turf blog but I also work with trees and ornamentals and I have sneaked in some tree stuff here before. If you don't care about trees, just skip it, but I do get a lot of questions about trees & ornamentals in golf courses so thought I'd pass in this news.

Dutch elm disease, chestnut blight, emerald ash borer, Asian longhorn beetle, sudden oak death... You might have heard of some of these tree diseases and insect pests.

There are always new problems arising to threaten our tree resources.

There is a new insect-fungus complex killing lots of black walnut trees in Colorado.
(I also know that a few folks consider black walnut a pesky tree because of the mess made by the nuts, but it is also a valued landscape tree in many sites, as well as an important part of native forests in the eastern half of the US).

Plant pathologist Ned Tisserat (formerly at K-State, now at Colorado State) and entomologist Whitney Cranshaw (Colorado State) have been working on this disease, and this past week representatives from other states in the region were in Denver to see the disease first-hand, learn about the biology and current research, and practice diagnosing it in the field.

There was a contingent of 7 from Kansas (yours truly and one more from KSU, three from the KS Forest Service, and two from the Kansas Department of Agriculture) who attended.

I took numerous photos and tried to post some here but, like with my dollar spot figure, I kept getting weird errors. D'oh! There are pics available in the link below.

The Colorado team showed us black walnuts in various stages of decline, then at two sites we had the opportunity to cut into several felled trees to look for the tiny beetles (adults and larvae were present), the canker symptoms, and the fungus. As we all know, there’s nothing better than field experience to really learn about a new disease or insect.

In Colorado, black walnut is only in landscape plantings. Here in Kansas and in other states up and down the plains we have both landscape and native black walnut, and we also have an important walnut timber industry. Regional plans are evolving to try to prevent spread of the disease, and to deal with the disease if it does appear in new states.

For more information about this disease, and photos, you can visit this website:

http://www.ext.colostate.edu/pubs/insect/0812_alert.pdf

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......

Red Leaf Spot Active...

Disease activity has basically gotten to a point of boredom for many of us who like to see new and exciting diseases. Dollar spot continues to be the number one problem in the Northeastern United States and this is not much of a departure from the past few weeks or so. Temperatures are finally getting cooler at night, but the forecast for some areas have temperatures reaching into the 80's again this week.

Much of the effort in terms of turfgrass management has shifted towards the necessary cultural practices needed to ensure healthy turf heading into the winter and also coming out of spring. Snow mold applications are still a couple of months away, but superintendents would be wise to check out some of the posts from Dr. Kerns in the Midwest region where he experiences some of the highest snow mold pressures around.

For me, last week was fairly exciting (although not exciting enough to come up with another PlayTurf cover) as some of our plots unexpectedly developed red leaf spot. While at Maryland, we heard a lot of buzz from superintendents in the field who felt that they were dealing with red leaf spot. However, upon further inspection we almost always found the disease to be late cases of Microdochium patch (aka, Pink snow mold or Fusarium patch) occuring during overcast weather. This caused some controversy to the point of almost having a manuscript rejected because the editors suggested that we did not probably identify Microdochium patch (the disease was rated in the first week of June in Maryland...which was highly unusual). I assured the editors that I was a major advocate of the cereal Lucky Charms and could easily distinguish my "crescent moon shapes" (typical of Microdochium) from that of a cigar (typical shape of the Dreschlera genus that causes red leaf spot).

Anyway, the real first time that I even saw red leaf spot was at the research plots at my first University of Massachusetts field day. I took out the trusty pocket knife and took a small sample back to the lab at UConn and sure enough...red leaf spot (sorry for whose ever plots those were...I only took a small piece). In reviewing the latest turfgrass fungicide updates from the University of Kentucky, the reports from Paul Vincelli generally hold true with the data collected from the unexpected disease in our plots. Our data suggest that the QoI fungicides held up equally well (Disarm did seem to provide slightly less control, but this was not significant). Although ProStar did not enhance disease activity in our plots as suggested by Dr. Vincelli, it definitely did not provide any suppression. Two surprises in the data relative to past trials were that myclobutanil (Quali-Pro) seemed to provide excellent preventive suppression AND that Emerald (which is only good for dollar spot and bentgrass dead spot) seemed to provide a moderate level of suppression of the disease.

Since this is my first time seeing data on red leaf spot in my own plots, please feel free to comment on your thoughts about the disease in trials conducted in your region. As with Jim's post last week about the lack of control with Curalan for early season dollar spot, we may continue to see differences in control of certain diseases based on these geographic regions.

Early-Season Programs for Dollar Spot Control

Early-season dollar spot control was mentioned in a previous post by Dr. Kaminski. Basically fungicides are applied long before symptoms develop in the field, which results in a significant delay in the onset of symptoms. The proposed theory behind early-season applications is they reduce the pool of initial inoculum of the dollar spot fungus enough to slow progression of the disease. A single early-season application will not provide season long control in the Midwest and it seems frivolous to employ an early-season treatment without changing the conventional fungicide program.

Therefore we are currently examining two different season long programs coupled with early-season applications to see if we can save fungicide applications. This experiment is being conducted at the OJ Noer Turfgrass Research and Education Center and at Milwaukee Country Club. We know from previous research that DMI's seem to slow disease progression the most in Wisconsin. We also know that chlorothalonil and vincozolin did not have any early-season activity in our trials, sorry John :).

Our approach was to make several different early-season applications when soil temperatures were between 55 and 60 F, which usually equates to May 1 in southern Wisconsin. Then we initiated follow up applications of a Banner Maxx tank mixed with Daconil Weatherstik (1 fl oz and 2 fl oz, respectively) every 21 days or Banner Maxx tank mixed with Daconil Weatherstil (1.5 fl oz and 3 fl oz respecitively) every 28 days. We included a non-treated control and a conventional spray program (Banner/Daconil 1.5 fl oz and 3 fl oz) that started on June 1st and continued on a 14 day interval. Next year we are going to include a conventional treatment sprayed on a 21 day interval. The aim of the project is to limit fungicide applications and/or the amount of active ingredient deployed while still maintaining adequate disease control.

In the interest of simplicity I have only presented four treatments: non-treated control, Early-season with 21 day follow-up (Banner Maxx early-season app.), Early-season (Banner Maxx) with 28 day follow-up and the conventional program. We had excellent dollar spot pressure at the OJ Noer this year as documented in the non-treated control plots. Plots receiving follow-up applications every 21 days at reduced rates reduced dollar spot severity compared to the non-treated control, but not to levels that would satisfy a golf course superintendent. The early-season with a 28 day follow-up worked almost as well as the conventional program.


Employing an early-season application for dollar spot followed up every 28 days with Banner/Daconil can save at least 2 fungicide applications when compared to a 14 day conventional program. Currently we are gathering budget numbers from 4 different golf courses to help us determine the economic benefit of these results. This work will continue next year, so please stay tuned. Also any comments or advice would be greatly appreciated!

As far as disease activity, the only disease I have seen this week in the field is rust. Dollar spot flared over the weekend, but nothing else has been reported or come through the TDL.

Spring Dead Spot Control in Hybrid Bermudagrass

Spring seems like a long way off, but now is the time to prevent your bermudagrass turf from looking like this upon greenup in the spring. Spring dead spot, caused by Ophiosphaerella korrae, can cause severe and long-term damage to bermudagrass on greens, fairways, roughs, athletic fields, and highly maintained landscapes if it is not properly managed.

There are many things that can be done to help reduce spring dead spot development. Probably one of the most effective practices is hollow-tine aerification. In the picture to the right, look how severe the disease is on the recreational area to the right as compared to the soccer field on the left. What's the difference? The soccer field was hollow-tine aerified three times in the previous year, whereas the surrounding areas were not.

In the Eastern United States, most people have good success in controlling spring dead spot with 1 or 2 fungicide applications in the fall. We've found that these applications are most effective when average daily soil temperatures are below 80 degrees and above 60 degrees.

The Midwest is a completely different story, however, as fungicides generally don't work very well against spring dead spot in that part of the country. Some have theorized this is because spring dead spot is actually caused by a different pathogen in the Midwest, where Ophioshpaerella herpotricha is most widespread. However, we've had great success in controlling O. herpotricha with fungicides in North Carolina in the few locations where it is present, so I tend to believe that different soil properties are responsible for the control difficulties observed in certain regions. Just keep in mind that what we find to work best in the Southeast isn't guaranteed to work everywhere.

Over the last 8 years, Rubigan has been the most effective and consistent fungicide for spring dead spot control in our trials. In fairways and athletic fields, we have seen excellent control from 2 applications (30 days apart) at 4 fl oz/1000 ft sq or a single application at 6 fl oz/1000 ft sq. On putting greens, which tend to be more susceptible to spring dead spot, I would recommend a total of 12 fl oz/1000 ft sq applied as either three 4 fl oz applications or two 6 fl oz applications.

Regardless of the program that you select, is critical that all of the applications are made before average daily soil temperatures dip below 60 degrees. This is the point at which bermudagrass plants start to shut down, and after this point the fungicide will not be absorbed and translocated in the plant.

There are other options for spring dead spot control. While Rubigan has been most consistent in our studies across a number of locations, we have also seen good to excellent control from Banner Maxx (2 applications at 4 fl oz), Headway (2 applications at 3 fl oz), and Eagle 20EW (2 applications at 2.4 fl oz) in some studies. Heritage has not provided effective spring dead spot control in our studies.

With any fungicide application for spring dead spot, it is very important that you water the fungicide into the root zone for best results. The pathogen is attacking the roots, rhizomes, and stolons of the bermudagrass plant, so that is where the fungicide needs to be. Most fungicides are absorbed quickly by the foliage, so irrigation must be applied right away before the spray dries on the leaves. On putting greens and fairways, typically 1/8" of irrigation is sufficient, but up to 1/4" may be needed on higher cut areas.

Dollar spot and large patch

Hello,

First, apologies for not posting last week. Ongoing computer issues continue to plague me. I actually tried, but there were mysterious errors, and it was nearly 7 pm on a Friday and I was too hungry and tired to figure it out. Then, guess what, our internet at home bombed out over the weekend thus ruining my plan to sneak in a late post on Saturday. Then, I gave up.

Dollar spot is the main disease right now. I have a trial in a Crenshaw/Cato (highly susceptible) area at our KSU research facility. Dollar spot pressure has increased dramatically in the past couple of weeks. The figure below shows disease progress in the untreated areas. Yesterday was the most recent rating date, with average severity of nearly 45%. That is, almost half the plot area was covered with dollar spot!



The image below shows two treated plots surrounded by untreated areas. If you look closely, you can see where our sprays did not quite hit right on the plot borders. (We ignore those in our assessments). This particular experiment is small, with only a few treatments. The treatments, which are all holding disease to zero, were:

Insignia (0.5 oz) + Trinity (1.0 oz) 14 -day
Emerald, 0.13 oz, 14-day
Emerald, 0.18 oz, 21-day
Honor, 0.83 oz, 14 day
Honor, 1.1 oz, 21 day

Large patch is the other disease on people's minds right now. We have a lot of zoysia around here, especially in the Kansas City metro area. Normally the 3rd or 4th week of Sept is recommended timing for preventative apps but with the cool, wet conditions I have been recommending going a little earlier (that's one of the things I tried to blog about last week, but did manage to send in a different KSU email newsletter). In fact, a few traces of large patch were visible at our research facility this morning. And, a superintendent in northeast KS emailed me and said that some large patch was becoming visible in some of his fairways. I'll be spraying about 14 different treatments in a large patch study at a golf course on Monday.

Moss is another favorite pet here at K-State and this morning I worked with a graduate student and my colleague Dr. Jack Fry to apply a few moss treatments in our study. We are looking at sodium bicarbonate (that's baking soda), potassium bicarbonate, MossBuster (you might have seen that advertised in trade magazines), and Quicksilver. The MossBuster is an essential oil (the label is not very specific), and we think it may be oregano because that's sure what it smells like. It makes us all hungry for pasta.

Finally, I wanted to note that despite all the problems caused by wet weather this year (such as leaf spots defoliating a bunch of trees, turf drowning in wet soil, etc), it has led to a bumper crop of some of our favorite prairie wildflowers.

Bacterial wilt, or not wilt? That is the question.

There's been a flurry of phone calls coming in to the lab in the last two days regarding bacterial wilt taking out Poa and bentgrass greens in Southern California this last week.

With temperatures hitting 90's and 100s in parts of SoCal last week, it's no surprise to see some death and destruction, but bacterial wilt may not necessarily be the cause. Here's some basic info about the disease that may help you recognize this potential issue.

Bacterial wilt is caused by Xanthomonas translucens or X. campestris, and tends at attack stressed, shaded or low fertility turf under warm or hot conditions. High humidity and mositure make the disease more severe. Symptoms start off as small yellow to whiteish spots that can spread and eventually turn into small reddish dead spots.

Two highly informative articles on the disease, symptoms, and control can be found here and here.

Control of the disease can be tough since there are no chemicals that offer complete control of the disease.

Because of our relatively dry west coast conditions, I would say that outbreaks of bacterial wilt are kind of like coordinating a trainwreck. You need some very specific conditions for the disease to fire, but when it does, the results can be spectacular.

Although the pathogen is difficult to control directly with chemicals - cultural controls such as raising mowing height, managing irrigation, reducing mechanical stress and avoiding mowing wet greens, can be implemented.

Most importantly, an accurate & timely diagnosis needs to be made for this disease. Symptoms can be identical to those caused by other stresses and it's difficult to accurately diagnose once the infected tissue is already dead (which is especially true if you let the disease explode before you take a sample). If you suspect the disease - get samples sent to a diagnostic lab right away.

In Other Local News....
The weather is getting a little better through much of the state with temps cooling down into the high 70s to 80s in most parts of the state, although parts of the Central and Inland Valleys will see 100s this week .

Not much change in expected, diagnosed and reported diseases. Anthracnose is still pretty active, and we have some gray leaf spot brewing in Orange county on both perennial ryegrass and kikuyugrass. Night time temperatures above 68F in southern and central California could mean Pythium outbreaks on cool season turf. Watch for this disease on low lying areas or those where drainage is poor/water accumulates.

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

All Quiet on The Midwestern Front

Sample submission has essentially ceased in Wisconsin. We have had a few samples of basal rot anthracnose, but really nothing else. Dollar spot is still lingering, although we are not seeing new spots develop in our forecasting experiments. The weather has been fantastic for fall aerifications and fall golf in the Midwest. Currently day time temperatures throughout the Midwest range from the low 80's to the low 70's and night time temperatures are ranging from the high 40's to high 50's.

The temperatures are ideal for cool-season grass growth, yet we have been fairly dry especially in Northern Wisconsin. Most of the Midwest did not receive any appreciable rainfall from Sept. 2 to Sept 8.

Dr. Derek Settle of the Chicago District Golf Association did report some Bipolaris leaf spot on a few creeping bentgrass putting greens, but really nothing else. In his weekly update he made an excellent point about this year. Although disease activity was low, it was still a very difficult year. We experienced one of the worst economic downturns since the Great Depression, which forced many golf course superintendents to make difficult budgetary decisions. From what I gathered from Derek's post, it sounded like many golf course superintendents in the Chicagoland area would rather deal with disease issues rather than the budget issues they dealt with this year.

On a completely unrelated note, for those that have gardens at the shop you should check your tomatoes for late blight. Late blight has been reported on tomatoes and potatoes in Illinois and Wisconsin. If you suspect that you have late blight submit a sample to a diagnostic lab and they will provide a recommendation on how to dispose of the plant properly.

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.

L.A., L.A., L.A. is on fire...

Yowza - Mother Nature ain't done with California yet this summer. Over the last week, we've had triple digit temperatures in much of southern California and bone-dry conditions that have lead up to wild fires breaking out to the southwest, east and north of the Los Angeles area. (Photo from the LA Times)

Time Lapse Test: Station Fire from Eric Spiegelman on Vimeo.

So far, the biggest fire is the Station Fire directly north of Glendale & Pasadena has burned over 225 square miles of forest (that's about 144,000 acres or approximately 1440 golf courses!) and only has about 40% containment. Heart felt wishes to those being negatively affected by this one.

As far as turf is concerned - those triple digits and dry conditons will surely have brought havoc upon cool season turf in southern California.

This last week brought anthracnose, rapid blight and summer patch, expect more of the same for this next week throughout California….

Hold on to your britches; just a few more weeks to go before we're in the clear!

Gray Leaf Spot and Pythium
No massive GLS outbreaks have been reported in California yet, although a report of its presence was made from Irvine last week and GLS oddly seems to be at its worst when we have summer wildfires in southern California.


Mike Wolpoff (Seacliff Country Club) sent this photo in this week of GLS on kikuyugrass. Applications of Daconil & Banner MAXX had held the disease at bay until this week when weather conditions pushed the disease into high gear. Sometimes high temperatures combine with coastal humidity and fog to really fire GLS outbreaks in coastally-influenced locations. Watch the developing high temps and humidity in parts of southern California that may fire GLS outbreaks on perennial ryegrass & kikuyugrass.

Night time temperatures above 68F in parts of southern and central California could mean Pythium outbreaks on cool season turf. Watch for this disease on low lying areas or those where drainage is poor/water accumulates.

Signing off from the right coast until next week (when I'm back on the left coast!).....

Fall Nitrogen Applications

Fall nitrogen fertilization is a widely accepted practice in the Upper Midwest. This is typically a good time to recuperate after a difficult summer, although we did not have a difficult summer this year. However, the timing of fall fertilization is critical in order to limit nutrient loss and snow mold development. My colleagues Dr. Doug Soldat and Dan Lloyd are investigating the uptake and utilization of fall-applied N to soil and sand based putting greens. The reminder of the post will focus on the research they have conducted on this topic. They conducted a survey of 42 golf courses in 2007 indicating that 55 % of the average annual N applied is applied between September and November. Why? The benefits that are often associated with fall N applications are improved fall color, earlier spring green-up, enhanced root development, an reserve carbohydrate storage. The majority of this research has been done in more temperate climates like the transition zone, which may not be applicable to the Upper Midwest.

A field study was initiated at two locations in the Midwest (Madison, WI and St. Paul, MN) on L-93 creeping bentgrass putting greens with either a sand-based rootzone or a soil based rootzone. N treatments included a unfertilized control, low N rate (0.5 lb N/1000 sq ft) and a high rate (1.0 lb N/1000 sq ft). Treatments were applied as ammonium sulfate on September 15th, October 15th or November 15th on both soil types and at both locations. Dr. Soldat and Mr. Lloyd collected clipping yields, color, and turf quality.

They found that the Sept. and Oct. applications stimulated a greening response that lasted until winter on both soil types, but no response was observed with the Nov. applications. The trends with spring green up varied with soil type. On the soil based putting green, Oct. treatments were the first to green, yet were later surpassed by the Nov. treatment. On the sand-based putting green, the high N rate applied in Sept. and Oct. were the greenest in the spring with no response from the Nov. applications.

Basically Dr. Soldat and Dan determined that Nov. N applications on sand-based putting greens did not provide a greening response. Therefore N applications should probably be completed by Oct. 15th.

There is a reason why I am writing about fall N applications. In my previous post about snow mold control, I did not mention that even the most effective fungicide can break down if the conditions are very conducive for disease development. One of the conditions that make turfgrasses more susceptible to snow molds, is over fertilization in the fall. Although we do not have data to support this yet, we consistently observe snow mold break through with late fall N applications (early to late November).

In conjunction with Dr. Soldat's research we have decided to examine the interactions of fungicide timings for snow mold and nitrogen application. We are going to initiate this study this year in collaboration with Dr. Frank Rossi.

Switching gears, this weekend was very cool with day time temperatures in the mid to low sixties and nighttime temps near 40. So Lane we are definitely in Fall! However I agree with Lane, do not let your guard down. The weather can change quickly and we could have a hot spell.

Is it fall already? Not quite...

Cooler temperatures across much of the southeast are going to bring a much needed break from summer this week. Most of our summer-time bentgrass diseases, like anthracnose, Pythium root rot, and brown patch, should start to shut down as the bentgrass begins to grow more vigorously.

It's nice to have a little reprieve, but be sure not to let your guard down. These summer diseases can re-activate quickly if temperatures rise again in the coming weeks. The picture to the right of a severe brown patch outbreak was taken in September 2004 after a period of warm, wet weather. Be especially wary during periods of wet weather or when major aerification and/or topdressing practices are planned.

If you've had problems with Pythium root rot this summer, additional fungicide applications are a good idea during wet weather, such as a tropical storm system. If you've had anthracnose problems this summer, a fungicide application just after aerification/topdressing is a good idea as well, as these abrasive practices can cause a flare in anthracnose activity.

Of course, dollar spot should start to become more active as the temperatures cool over the next month. If this disease has been a major problem for you in the past, be sure to start preventive applications soon before symptoms of the disease appear. Once the symptoms appear, dollar spot becomes much more aggressive and difficult to control.

For those with bermudagrass greens, this is the time of year when leaf spot diseases, such as Curvularia and Bipolaris, start to come in. Preventive fungicide applications for these diseases are recommended during wet, cloudy weather or after topdressing applications. Chlorothalonil typically does a good job of keeping these diseases suppressed, but if you are looking for something that lasts longer, iprodione is a good choice.

Most people think of Pythium blight as a hot weather disease, but on bermudagrass greens, most of our problems with this disease are during cool, wet weather in the fall and spring. The image to the right of Pythium blight symptoms was taken on Champion bermudagrass greens last October. In this case, the symptoms appeared very similar to a leaf spot disease, but typical leaf spot fungicides were not controlling it. Once a sample was diagnoses as Pythium blight at our Turf Diagnostics Lab, the problem was easily controlled with an application of mefanoxam (Subdue Maxx).

Soon it will be time to start thinking about controlling large patch and spring dead spot in the warm-season grasses. Stay tuned - this will be the topic of next week's post.