2008-2009 GCSAA 
Chapter Cooperative Research Program Progress Report 
Project title: Management and biology of Brown Ring Patch on Annual Bluegrass Greens 
  Researchers: Dr. Frank Wong, Department of Plant Pathology & Microbiology, 
University of California, Riverside, CA 92521 
Dr. Larry Stowell, PACE Turfgrass Research Institute, San Diego, CA 92109 

Total Funding Request: $62,000 over 2 years from the GCSA Environmental Institute 
for Golf, California State GCSA and 6 Regional California GCSA Chapters

Complete Report >>>> HERE

Mark M. Mahady, President Mark M. Mahady and Associates, Inc. 
Apri1 28, 2008 

New Turf Disease Blog Available:

Prof. John Kaminski at Penn State has started a new blog featuring national updates and tips on turf disease management here:

http://www.turfdiseases.blogspot.com/

It's updated daily, featuring five reports from five different regions from five different plant pathologists. These bloggers are experts on a wide variety of diseases and you may even know some of them!

There's some posts on sping dead spot up there right now but check it out and let us know what you think.

On the other hand - the range in temps we are seeing will make it hard to say what will pop up - in any case, I think it's going to be ugly after this heat wave. 
Colorado Rapid Blight

This last week, we got an unexpected hit of rapid blight from Colorado. From the photo here, you can see how much damage occurred to the greens. Although Colorado courses donÕt normally deal with rapid blight, it seems like the disease may be fairly widespread and is just waiting for elevated salt levels to be able to damage annual bluegrass greens. Notice in this picture that only the annual bluegrass has been taken out and the creeping bentgrass looks just fine.

New Information and Presentations up on the Web

In the next few days, we'll be posting past seminars on www.turfpathology.ucr.edu for Spring Diseases, including Brown Ring Patch, Rapid Blight, and Anthracnose. Keep checking the website this week for the latest updates.
 

Help Us Help You – Fill Out Those Sample Information Sheets

Please make sure to download and fill out the sample information forms when sending in diagnostic samples. Tracking down distributors and superintendents takes time away from diagnosing other samples in the lab, and most of all, we want to get the right diagnosis to the right person, right away.

The USDA and CDFA have become very stringent with samples and rejected a few boxes in the last few weeks without supporting sample info. This had lead to delayed diagnoses and affected our ability to get back to you ASAP with a disease solution. Please fill out the lab diagnostic forms and include a copy of the federal and state permits to make sure they don’t intercept and throw your stuff away.

A copy of our USDA and CDFA permits can be found here:

http://www.turfpathology.ucr.edu/Downloads/permits/USDApermit76444.pdf

http://www.turfpathology.ucr.edu/Downloads/permits/CDFApermit2443.pdf
 

Make a preventive Pythium application when you know you are in the red zone for the disease since Pythium can cause severe turf loss in 24hrs so its important to watch out for it.

Fungicides Available for Control of Pythium Blight
 

Fungicide	Class	Example of available product	Use Rate (per 1 000 sq. ft)	Application Interval (days)
mancozeb	Multi-site (Dithiocarbamate)	Fore	8.0 oz.	5
mefenoxam	Phenylamide	Subdue MAXX	0.5 to 1.0 fl.oz.	10 to 21
fosetyl-Al	Phosphite	Aliette	4.0 to 8.0oz.	14
fosetyl-Al	Phosphite	Chipco Signature	4.0 to 8.0oz.	14 to 21
phosphorous acid	Phosphite	Alude	5 to 10 fl oz	14 to 21
azoxystrobin	QoI	Heritage	0.4 oz.	10 to 14
fluoxastrobin	QoI	Disarm	0.18 to 0.36 fl oz	14
pyraclostrobin	QoI	Insignia	0.9 oz.	10 to 14

Reminders for Diagnostic Lab Samples
Systemwide University of California Service Workers Strike – Use Fed Ex for this Week’s Deliveries.

From Monday July 14 to Friday July 18 – there will be a UC Systemwide strike for the UC service workers. U.S. Postal Service and UPS deliveries will be affected, but the effect of Fed EX will be minimal. Please send packages by Fed EX this week to avoid any delays for us getting the packages. If you are sending samples – please let us know what the tracking # is so we are sure that they did not get delayed/misdelivered. Thanks!

Please remember to completely fill out and include the sample submission forms in packages. It helps us respond to the right people in the least amount of time. Our diagnostician, Dr. Naveen Hyder, will be updating the website and sample submission forms in the near future.

Also – we hate to charge, but we need to cover our operating costs. Please try to send in payments as soon as you can and if there are billing problems, please contact us as soon as possible. 

Fungicides available for Grey Leaf Spot Control
 
 

Fungicide	Class	Example of available product	Use Rate (per 1 000 sq. ft)	Application Interval (days)
thiophanate-methyl	Benzimidazole	Cleary's 3336	4.0 to 8.0 oz.	7 to 14
mancozeb	Multi-site (Dithiocarbamate)	Fore	8.0 oz	14
chlorothalonil	Multi-site(Nitrile)	Daconil Ultrex	1.8 to 3.25 oz.P/ 3.7 to 5.0 oz.C	7 to 10 P/14 C
azoxystrobin	QoI	Heritage	0.2 to 0.4 oz	14 to 21
pyraclostrobin	QoI	Insignia	0.5 to 0.9 oz	14 to 28
trifloxystrobin	QoI	Compass	0.15 to 0.2 oz./0.25 oz.	14 (low rate)/  21 (high rate)
propiconazole	SI	Banner MAXX	1.0 to 2.0 fl.oz.	14
triadimefon	SI	Bayleton	0.5 to 1.0 oz. P	14

 P    preventive rate 
C   curative rate 

Resistance to QoI-fungicides has developed at some locations, be cautious if you have used these fungicides repeatedly for gray leaf spot control. 
SI-fungicides may cause some discoloration of turf under heat stress conditions.
It is suggested that all systemic fungicides should be tank mixed with a mancozeb or chlorothalonil for increased effectiveness of the application. 

Gray Leaf Spot in Arizona 
A confirmed hit was reported by Gabriel Towers at the University of Arizona today from a perennial ryegrass course north of Phoenix. Details to follow.

Pythium Blight 
Night time temperatures above 68 degrees F will also be high enough for the rapid development of Pythium blight. A rule of thumb to follow, if night time temperatures + relative humidity are equal to or above 150, there’s a good chance for a Pythium outbreak. 

Fungicides Available for Control of Pythium Blight
 

Fungicide	Class	Example of available product	Use Rate (per 1 000 sq. ft)	Application Interval (days)
mancozeb	Multi-site (Dithiocarbamate)	Fore	8.0 oz.	5
mefenoxam	Phenylamide	Subdue MAXX	0.5 to 1.0 fl.oz.	10 to 21
fosetyl-Al	Phosphite	Aliette	4.0 oz.	14
fosetyl-Al	Phosphite	Chipco Signature	4.0 oz.	14 to 21
azoxystrobin	QoI	Heritage	0.4 oz.	10 to 14
pyraclostrobin	QoI	Insignia	0.9 oz.	10 to 14

Curvularia on Annual Bluegrass
We have been seeing Curvularia blight developing on stressed annual bluegrass. This is another anthracnose-like disease that attacks stressed turf. 
A photo of Curvularia can be seen here: http://www.paceturf.org/photo/showphoto.php/photo/123/sort/1
Although many fungicides labeled anthracnose & summer patch can control Curvularia, there is a chance that some are not completely controlling this stress pathogen. You may want to integrate an additional application of mancozeb plus iprodione onto heat stressed Poa greens if you see this fungus developing on older, scenescing leaves. 

The Fungus that Ate Sheboygan
Just a quick picture from Larry Stowell’s photo gallery of Rhizoctonia zeae (sheath and leaf spot, or high temperature brown patch) on bermudagrass/perennial ryegrass from a sports field in San Diego. This developed 24 hours after incubation in the lab. Both R. zeae and W. circinata var circinata (Brown Ring Patch) can make this ‘Don King’ like mycelia over night. Pretty impressive. 
http://www.paceturf.org/photo/showphoto.php/photo/1052/cat/1

Reminders From Last Week

Choosing Gray Leaf Spot Resistant Perennial Ryegrass
So far so good as far as no major GLS outbreaks being reported on perennial ryegrass this year. Although overseeding is still a month or more away, it’s not too early to think about what to use. Definitely choose gray leaf spot tolerant varieties to help reduce the impact of the disease. Dr. Bruce Clarke from Rutgers University reminded me today that it would be a good idea to consider using a blend of different tolerant varieties as a preventive measure. Some varieties may be better than others under certain conditions and it would help prevent losses if a strain of gray leaf spot developed that could overcome some of the genetic tolerance in a single variety. That makes sense to me. 

Fairy Ring Control 
Fairy ring and localized dry spots are difficult problems to manage. Read up on the latest on fairy ring from a joint research article written by Mike Fidanza (Penn State, Reading), Bruce Martin (Clemson) and yours truly here in the May edition of Golf Course Management.
Treating Fairy Ring with Fungicides and Soil Surfactants and an article on localized dry spot and surfactants from Keith Karnok and Kevin Tucker (Univ. of Georgia) in the June edition of GCM
More FAQs about LDS: Hot spots and label rates
* you may need your GCSAA user name and password to view these

Recent Diagnoses and Observed Disease Activity: Chart ..... Here

University of California
Turf Pathology Laboratory
Department of Plant Pathology & Microbiology
www.turfpathology.ucr.edu
Phone: 951-827-2936 

Fungicides available for these diseases are listed below: >>> http://www.californiagcsa.org/uc%20turf%20disease%20diagnostic%20lab%20services-10-8,%2010-15.htm

White Leaf? 
Mike Parks from Target Specialty Products sent this group of photos from a green in Sonoma Co. showing Poa White Leaf – this is still a huge mystery disease for me with no proven treatment. Sometimes it recovers, sometimes it dies out. The best thing is promote practices that allow for good Poa growth to allow non-effected plants to fill in on the weakened areas. 
http://www.paceturf.org/photo/showphoto.php/photo/935/sort/1/cat/1/page/1

http://www.paceturf.org/photo/showphoto.php/photo/933/sort/1/cat/1/page/1

http://www.paceturf.org/photo/showphoto.php/photo/934/sort/1/cat/1/page/1

Dr. Frank P. Wong
UC Extension Specialist
Department of Plant Pathology
University of California
Riverside, CA 92507
Cell: 951 315 0101
Lab: 951 827 2936
Fax: 951 827 4292 

Invoices and Bills for Diagnoses 
If you have invoices from the turf lab, please try to send in payment as soon as you can. We are bottoming out on funds this summer and need to keep the diagnostic lab up and running. If you need a extra copy of the reports and invoices please let Carrieann know by emailing to turfpathology@ucr.edu, or calling us at the lab at 951-827-2936 

Poa White Leaf and other Mystery Diseases 
This last week, a course in Ventura Co. sent in samples from greens with little white and yellow spots. Up close, the affected plants were white from stem to shoot. This is very characteristic of Poa White Leaf which is caused by a phytoplasma, a bacteria-like pathogen that is almost virus like in that there are no effective chemical treatments. We still don’t know much about how this pathogen causes disease; sometimes affected spots turn green again, sometimes they die out. Algae or Blue Green Cyanobacteria can also cause yellow spots. Many of these algae can secrete a toxin that turns plants yellow. Poa White leaf is on the list of diseases to work on, but unfortunately there are a lot of others in the front of the line (gray leaf spot, anthracnose, Waitea Patch, etc...) 

Pictures are posted here:
http://www.paceturf.org/photo/showphoto.php/photo/853/sort/1/cat/1/page/1 

http://www.paceturf.org/photo/showphoto.php/photo/855/sort/1/cat/1/page/1 

Also in Plumas Co. two courses almost side by side to each other have been seeing the same symptoms – what looks like summer stressed, chlorotic areas of turf. But no definite answers were found in the samples. Any ideas out there? 

http://www.paceturf.org/photo/showphoto.php/photo/852/sort/1/cat/1/page/1 

http://www.paceturf.org/photo/showphoto.php/photo/854/sort/1/cat/1/page/1

Finally, we are seeing some strange symptoms in the aftermath of Waitea Patch attacks. I was skeptical of  initial reports of “greening” inside rings affected by Waitea, but here it is: 
http://www.paceturf.org/photo/showphoto.php/photo/851/sort/1/cat/1/page/1

In many locations were recovery from damage has been slow – soil nitrate levels are often low (below 4 ppm) and the thatch is breaking down in the area of the initial yellow ring. Perhaps that no nitrogen = no building blocks for plants = no recovery. The greening inside of the rings? We have not associated a definite fairy ring fungus with it, but perhaps the low fertility greens are responding to the Waitea weakened or killed grass being broken down by saprophytes and releasing N. If you have an idea – let us know. 

*OLD NEWS AND REMINDERS* 
Start Scouting for Gray Leaf Spot Now on Perennial Ryegrass and Kikuyugrass 
The first week of July has traditionally been the time when the first gray leaf spot samples start rolling in. 

If your maximum daytime temperature + % minimum relative humidity > 140-145, start scouting for Gray Leaf Spot. Historically severe outbreaks have taken place when max T + min RH > 150-160. A primer on GLS is located at http://www.ncga.org/turf/gray.htm 

Looking at the trends at a few locations, it seems that areas like coastal LA, Irvine and San Diego are most at risk right now.

Although the > 140 index is a rule of thumb for scouting, there are two other things to consider. Generally, the maximum daytime temperature has to be consistently above 70 to 75ºF and the pathogen has had to have a few cycles to get started as the first set of infections may be unnoticed or in less intensively managed areas in roughs – you may need a few good infection periods before something becomes noticeable. 

From the chart below based on CIMIS-station data, you can see how the index has been developing since June 1. Areas like Riverside and El Dorado have a relatively low index since – although it’s been hot, the humidity has generally been low. Santa Monica would appear to have the highest index so far, with a good combination of heat and humidity. Areas like Irvine, San Diego and Santa Barbara appear to have similar index numbers, but I would suspect the threat in Santa Barbara and San Diego would be less, since Irvine has had 22 days above 70ºF, while Santa Barbara and San Diego have only had 15 and 18 days above 70ºF. 

Anthracnose and Donuts
The donuts are claimed! Diamond Oaks Golf Course in Roseville sent in a sample that came in Tuesday. It was a classic set up for anthracnose as far as getting greens fast and firm for tournaments. Two dozen Krispy Kremes are on their way to Roseville today; partially out of consolation, partially just to say thanks as far as keeping us up to date on the start of the anthracnose season. 

Larry Stowell reported getting his first anthracnose sample on Monday from a course in Irvine – so it appears that it’s active in both parts of the state, in both warm (Irvine) and hot (Roseville) weather. 

Fungicides recommended in a mid-season anthracnose program, based on UCR fungicide trial results over the last two years include the following applied at 14 day intervals: 

4 oz Signature + 3.2 oz Daconil Ultrex 
4 oz Signature + 0.33 oz Medallion 
4 oz Signature + 4 fl oz 26GT 

0.33* to 0.50 oz Medallion 
4 oz Endorse* 
(* optionally, tank mix with 1.8 oz Daconil Ultrex for added effectiveness) 

3.2 oz Daconil Ultrex 

Since Summer Patch is often active at the same time, one of the following should be applied once a month during the summer to annual bluegrass greens 
0.4 oz Heritage
0.9 Insignia (best for locations with rapid blight activity) 

Reminder - Start Scouting for Gray Leaf Spot Now on Perennial Ryegrass and Kikuyugrass
If your maximum daytime temperature + % minimum relative humidity > 140-145, start scouting for Gray Leaf Spot. Historically severe outbreaks have taken place when max T + min RH > 150-160. A primer on GLS is located at http://www.ncga.org/turf/gray.htm

By the way – there will definitely be a prize for whoever gets the first gray leaf spot....details to come. 

*OLD NEWS AND REMINDERS*
Take All Patch on Bentgrass Greens 
If you took TAP-damage this fall and winter, it may not show up until now under summer stress. If your bentgrass roots are shorter than normal now – you may be in big trouble when the mercury starts rising. Keep your fertility adequate, promote deep rooting and hand water to keep greens from summer-stressing on you.

Bipolaris and Rhizoctonia on Perennial Ryegrass
It’s hot enough in some locations so that ryegrass is wanting to shut down in the summer heat. As a result of the reduced growth potential – we are starting to see more diseases pop up on ryegrass now. We still haven’t seen any gray leaf spot yet, but some “stress” diseases like Bipolaris Leaf Spot and Rhizoctonia Blight can be very damaging on heat and traffic stressed turf. 

Waitea Patch Control Trial at Torrey Pines. 
On May 12, we had the chance to perform a trial with Candice Combs at Torrey Pines GC with Drs. Larry Stowell and Wendy Gelernter from PACE Consulting. Fungicide applications were made on May 12 and evaluated on May 19 and May 24, here are the results from the May 24 evaluation. 
 

Waitea Patch Marches on.

This picture was sent in this week from LA county – it’s a great shot of Waitea producing rings with “scalloped” edges on annual bluegrass. So far we have not isolated any R. cerealis from rings like this in 2006.

Price Structure Change
The price for disease diagnosis has increased by 3% this year to $98 to cover increases in University of California fees.

Invoices and Billing System Changes
Starting this year, the University is changing the way we are allowed to bill and charge for diagnostic services. The University has been instructed to be accountable for services and thus will start charging a $12 late fee for invoices not paid after 60 days of billing.
The Turf Pathology Lab does not benefit from this new billing system or the assessment of late fees; but the University of California administrators are adamant about having more control over sales and service accounts on campus..
When sending in samples, please make it clear who is being charged for samples. This is especially true if you are a distributor or consultant who is sending in samples for a client. We want to avoid accidental double billing or having the University assess you late fees.

Waitea Patch Control Trial at Torrey Pines. 
On May 12, we had the chance to perform a trial with Candice Combs at Torrey Pines GC with Drs. Larry Stowell and Wendy Gelernter from PACE Consulting. Fungicide applications were made on May 12 and evaluated on May 19 and May 24, here are the results from the May 24 evaluation.

** averages followed by the same letter are the same (p < 0.05, Duncan-Waller k-ratio test) 
*** based on comparisons between initial and final ratings amongst plots. 

Candice had treated the greens with Banner MAXX about a week prior to the start of the trial and the first application didn’t stop the disease entirely. Initially, the plots were all about the same with regard to disease development, but after one curative application (applied at 2 gal/ 1000 sq ft with TeeJet 8002 flat fan nozzles), it seemed that all but Clearys 3336 had some effect in reducing the disease. Compass had the least effect, but was statistically equivalent to the remaining treatments. Numerically, Banner MAXX, Medallion, Endorse, Heritage and ProStar were the strongest based on the May 25 rating. 

There was some variation in performance – ProStar was strong on May 24., but weaker on May 19; the same was true for Insignia to a lesser extent. 26GT appeared to have good activity on May 19, but less so on May 24.

Isolations from the green on May 12 indicated that the primary pathogen species was Waitea circinata var circinata, but there was some Rhizoctonia zeae present. It takes about 14-21 days to tell them apart 100%, and we were surprised to see some R. zeae, but I don’t think it changes the trial too much in this case. 

The jury is still out as far as the best treatment. With regard to Banner MAXX, maybe more than one treatment is needed for effective control. 

Just this week, two courses (Newport Coast, Palos Verdes) said they got good control with ProStar and one didn’t (Santa Barbara). One location in Napa treated with Heritage and the fungus was still active. An additional location (Tustin) indicated that 4 oz of Endorse also cleaned up the disease. We are in the process of confirming which species affected these locations. 

Additional details from the trial can be found at the PACE website, including additional data from a rating on May 19. www.paceturf.org – the info is located in the photo gallery: http://www.paceturf.org/photo/showphoto.php/photo/792/sort/1/cat/1/page/1

The bottom line: 
(1) Banner MAXX, Medallion, Endorse, and Heritage appear to have the best activity in our trial on both rating dates. ProStar looked very good on the second rating date and 26GT and Insignia activity were more variable overall. 
(2) There may be a mix of Rhizoctonia species affecting greens, possibly explaining variations in fungicide activity 
(3) There is some variation in fungicide effectiveness at individual locations – could be possible case by case resistance development or something else like nozzle selection/spray pressure/water volume. 

It’s critical that we get more isolates from more locations as well as feedback from folks as far as what is and what is not working --- it’s still a mystery we are trying to figure out! We’ll have some lab tests done soon to try to help sort this out. 

Waitea vs Rhizoctonia
Since starting to talk about Waitea, I have gotten a lot of questions since I seem to use the term Waitea and Rhizoctonia interchangeably. It’s a little confusing, but here’s the clarification. 

There are four diseases of turf caused by Rhizoctonia type fungi on turf (one disease, Sheath and Leaf Spot is associated with either of two fungi), these are listed below: 
 
 

* name for disease on bentgrass proposed to the Japanese society of Phytopathology 
** preliminary name for disease on annual bluegrass not yet proposed to any society
*** not formally assigned; no Anamorphic Name has been formally approved 

Fungi get two names – a Telemorphic Name describing the sexual form of the fungus, which is often rare in nature and an Anamorphic Name for the asexual state. For example, the Yellow Patch pathogen can be called Ceratobasidium cereale or Rhizoctonia cerealis; but since we see the asexual form nearly 100% of the time, most pathologists just say Rhizoctonia cerealis. 

For The fungi causing Sheath and Leaf Spot/Brown Ring Patch/Waitea Patch – it’s a little more complex. Morphologically, they all look about the same thus the Teleomorph name was assigned as Waitea circinata. Since there were small differences in biology between these – they divided this species into three varieties: oryzae, zeae and circinata. The old names for two of these groups were Rhizoctonia zeae and Rhizoctaonia oryzae, which have been renamed Rhizoctonia circinata var zeae and Rhizoctonia circinata var oryzae, respectively. 

At the time, when we figured out that we had a new pathogen – there was no accepted “Rhizoctonia” name for it, so we had to use the assigned Teleomorphic Name, Waitea circinata var circinata and also called the disease “Waitea Patch” since it was not 100% clear if Rhizoctonia circinata var zeae and Rhizoctonia circinata var oryzae were involved. 

To boil it down to the syrup: 
(1) Waitea circinata var circinata is a Rhizoctonia-disease, that no one had assigned a Rhizoctonia-species name to. 
(2) “Brown Ring Patch” is the Japanese name for Waitea circinata var circinata on bentgrass; we are using “Waitea Patch” for the disease in the U.S. on annual bluegrass until we know for sure its 100% the same and to separate it from other Rhizoctonia diseases. 
(3) If you thought pathologists were bad, taxonomists (the ones who name fungi and other things) are ten times worse. 

***Old News*** 
Updated Instructions for Disease Diagnosis Samples
New instruction and submission forms are available online at ucrturf.ucr.edu 
The sample submission form can be filled out on line or printed out and filled in by hand. If you have the latest version of Adobe Acrobat Reader, you should be able to open the file and fill it out directly by clicking on the buttons or fields and just typing in your information. 

Here’s a picture of Waitea patch that Kent Davison (Industry Hills) sent in last May on annual bluegrass – it looks just like Yellow Patch, but starts at temperatures usually above 65ºF 

Waitea circinata var circinata in culture. This is a 10-day old culture on ¼-PDA, you can tell it apart from other Rhizoctonia species because if makes irregular shaped orange to salmon sclerotia in culture that are both on the surface and submerged in the media. 

Anthracnose and Summer Patch Preventive Programs 
Soil temperatures in many parts of the state appear to be going over 65 to 68ºF – which means it’s time to start preventive applications for anthracnose and summer patch! At this time, we are recommending two to three applications of an SI-fungicide with high intrinsic activity (Banner > Eagle > Bayleton), watered into the root zone, as the start of your summer preventive program. 

Just as a reminder, here are fungicides with microdochium patch/pink snow mold and cool temp Rhizoctonia activity (x = labeled for use)
 
 

Frank P. Wong
202 Fawcett Laboratory
Department of Plant Pathology
University of California
Riverside, CA 92507
Cell: 951 315 0101
Lab: 951 827 2936
Fax: 951 827 4292

Gray Leaf Spot

Gray leaf spot is still a threat during overseeding, especially if temperatures are high and there is sufficient leaf wetness for disease to develop; keep an eye out for the max temp + min RH > 140 as a risk assessment. 

It’s almost time for overseeding on California courses - just a few quick notes with respect to some diseases: 

Gray Leaf Spot
In overseeding bermudagrass or sweetening-up existing perennial ryegrass plantings, it’s good to try to incorporate some 
gray leaf spot tolerance onto the course. 

In our variety trial that we put out in Newport Coast this last year, there was no significant difference between varieties used since disease pressure was not very high in the trial location. 

Treatment #               Variety Name            GLS %            Turf Quality (9= highest)
1                                 Repell                         9.0                   7.0
2                                  Panther GLS               2.8                   6.9 
3                                  Prelude GLS              13.8                  6.6 
4                                  Palmer IV                   9.5                   6.8 
5                                  Palmer GLS               23.8                  6.8 
6                                  APR 1668                   7.0                   7.1 
7                                  Prelude IV                 16.3                  6.8 
8                                  Barlennium                12.5                  7.1 
9                                 Pinnacle II                  4.5                   7.2
10                                SR 4220                      8.8                   7.1 
11                                Peregrine                    4.5                   7.3 
12                                SR4550                      7.5                   6.9 
13                                PST-2AM                   8.3                   7.0 
14                                PST-2MNG                4.0                   7.2 
15                                Silver Dollar               12.5                  6.9 
16                                Paragon                      3.3                   6.9 

On certain parts of the course at the trial location, you could see a clear difference between GLS and non-GLS tolerant varieties (GLS tolerant is on the right hand side) 

 You can see a list of gray leaf spot tolerant varieties athttp://ntep.org/data/pr99/pr99_04-8f/pr9904ft25.txt 

A caveat for tolerant varieties though - Dr. Bruce Clarke at Rutgers University has commonly observed that even highly tolerant varieties can be severely affected by the disease if over fertilized and over irrigated in the summer. 
 

Pythium Blight
The courses in the low desert are gearing up to overseed with cool season turf as well, and Pythium is always a constant threat.  As a general rule, if average nighttime temperature plus average relative humidity s equal to or above 150, then the risk for Pythium blight is high.

A short write up on Pythium control is available at: 
http://www.apsnet.org/education/LessonsPlantPath/PythiumBlight/mngmnt.htm
 

With regard to chemical control; on greens make sure to apply fungicides past the green onto the collar to provide an extra buffer zone of greens protection from Pythium that may be outside of the green. 

Also, cases of Pythium resistance to mefenoxam/metalxyl (Subdue, Apron, etc) have been documented in California and other locations.  If you have had performance issues with this class of fungicide or just want a little extra insurance, you may want to consider using a tank mix with other pythium fungicides or using these in rotation with mefenoxam. 
 
 

Fungicide	Common Trade Names	Comments
azoxystrobin	Heritage	QoI fungicide, best used at high labeled rate
pyraclostrobin	Insignia	QoI fungicide, best used at high labeled rate
etridiazole	Terrazole	an aromatic hydrocarbon - registration status in CA unclear
mancozeb	Fore, Dithane	Contact fungicide only, may need to be reapplied frequently
phosphonate, phosphite	Aliette, Signature	systemic Pythium fungicides, best used on mature turf not newly germinated seedlings, may not have good knock down activity
propamocarb	Banol	not registered in CA, although current Bayer label does not specifically restrict usage in CA

The fungus we are picking up now in much warmer weather (80ºF +) is highly suspected to be Rhizoctonia zeae. 
According to Randy Kane, Director of Turfgrass Programs for the Chicago District Golf Association and Bruce 
Martin at Clemson University, R. zeae can frequently cause the “yellow ring” or patch symptoms on greens when
it’s hot and humid.  We are working on this in the lab right now to confirm what species we have. 

More info on the different Rhizoctonia species can be found at:
http://www.apsnet.org/education/LessonsPlantPath/Rhizoctonia/symptom.htm

As far as fungicidal control - most fungicides labeled for regular Rhizoctonia brown patch (R. solani) are effective 
against R. zeae with the exception of thiophanate-methyl (Fungo, Clearys 3336) - although we have no California 
specific data I am aware of.

Superintendents have reported no recovery from suspected R. zeae infections after fungicide applications. 
It could be that the fungicides are working, but it’s too hot for the annual bluegrass to recover. 

Just a quick reminder of what’s commonly recommended against the 3 Rhizoctonia species.