1. Seashore paspalum grows wild in Asia sparingly and only in the wettest areas. However, it is common to find bermudagrass or zoysiagrass growing in all types of environments (sun, shade, wet soils, dry soils) in the wild. Seashore paspalum has been growing in the wild in Asia for well over 100 years but it does not spread except in swamps. There is an excellent paper in Weed Science (Xie et al., 2009) about seashore paspalum and weeds in southern China. The paper is titled "Spatial and Temporal Dynamics of the Weed Community in a Seashore Paspalum Turf" and the researchers set out to measure the spread of weeds through a low-maintenance stand of seashore paspalum at Guangzhou. Weeds were measured every two months during 2007, which was five years after planting, and the turf had not received any herbicides. The somewhat surprising conclusion? I quote: "the seashore paspalum turf has been naturally replaced by manilagrass." Manilagrass is Zoysia matrella. Be aware that seashore paspalum is a grass that will tend to be overtaken by other grasses.
2. Seashore paspalum is pretty, but zoysiagrass is pretty too. And Zoysia matrella has a finer leaf blade than seashore paspalum and is easier to maintain. And some golfers don't like to play from seashore paspalum fairways. Their complaint is that the ball sits too low. Sometimes the seashore paspalum just doesn't want to grow and when that happens the ball sits down a lot more on paspalum than it does on bermuda or zoysia. Here is seashore paspalum at 15 mm and Zoysia matrella at 15 mm. Can you tell which is which? And if you can, is seashore paspalum that much better?
3. My advice for controlling dollar spot on seashore paspalum in Southeast Asia is to increase the growth rate of the grass. On greens and tees, use fungicides as necessary to prevent or control dollar spot. Use a chemical that will control dollar spot, and by all means apply it at the proper rate. On fairways and in roughs, however, it is usually too expensive to apply fungicides to control this disease. Seashore paspalum requires extra care to survive in Southeast Asia or it will be overtaken by zoysia or bermuda. Keep a constant growth rate by applying optimal amounts of nitrogen fertilizer (usually about 3 g N per square meter per month) and maintaining adequate soil moisture. If seashore paspalum growth slows because of inadequate nitrogen or dry soil conditions, it becomes extremely susceptible to dollar spot. Mow frequently with sharp mowers, and that will remove the dollar spot symptoms that do appear.
Then, as Jim was mentioning, it's also a good time to reflect on the physiological stress of 2010 and perhaps set some plans related to adjustments in agronomic practices, playability, etc. Summer 2010 was a beast, but there are things to learn from it that can help everyone in the future.
**You can read Frank's post in detail to see what I'm talking about :)
50's 50's 50's
Overnight lows in the 50's are continuing to alleviate stress problems from this summer. Jim said his phone has been fairly quiet, and mine has been too. It's nice to be thinking about things like fall renovations, overseeding, etc, instead of fighting for turf survival 24/7. In my region, those of you with zoysia or bermudagrass might start preparing for fall apps for large patch or spring dead spot. In Kansas, apps for SDS have been pretty inconsistent but a little farther south, in Oklahoma, there's been some recent research on timings for better efficacy. It's all summarized nicely in the August issue of Golf Course Management in an article by Nathan Walker.
More thoughts on summer stress, 2010
At this link you can find more info on the extreme stress conditions of 2010, including some comments and data posted by a Kansas City area superintendent that clearly demonstrate how wicked this summer was. It's always refreshing to hear directly from guys in the field:
Why turf is like the incredible, edible egg
Larry Stowell and Wendy Gelernter are at it again. They are fast becoming the turf video stars of the internet. At the following link you'll find a short video from PACE turf on why turf gets damaged by heat:
No salmonella risk involved :) The video is aimed at a golfer audience.
The incredible, edible sedge
I was just joking around last week, but apparently sedges ARE edible. Here's a comment that came in on my Kansas State website:
Ah, but nutsedge IS edible! The little nutlets that make this weed a pain to control are perfectly edible. Cyperus esculentus…esculentus means edible. You can even buy Cyperus esculentus var. sativus which has been especially selected for eating quality. The nutlets are usually called Chufa nuts and they are used for a popular drink in Spain – Horchata de Chufa!
I’ve eaten chufa nuts and they actually are quite tasty. If I can find some nutlets of var. sativus, I’m planning to plant them in a container next year.
-Rebecca McMahon, Sedgwick County Horticulture Agent
And, this one came in via the Facebook page for THIS blog:
Yes, you can eat nutgrass. it’s part of Chinese medicine.
Yes, you can eat spurge, acturally we eat them fresh and dehydrate them so we can eat on Spring Festival.
Now you know why America has more weeds to deal than Chinese
There’s more information about the edible nature of yellow nutsedge (Cyperus esculentus) online here:
And, if you hunt online you’ll find more.
Now, if only we could eat dollar spot, brown patch, Pythium, etc etc.
Two plant pathogens that ARE edible are corn smut:
This is a delicacy in Mexico, called Huitlacoche (sometimes spelled cuitlacoche). I’ve eaten it in various dishes. Lots of recipes available online!
And, another edible (err, drinkable..) pathogen is Botrytis cinerea. In most cases Botrytis causes a nasty fruit rot. You’ve seen this on strawberries that get gray-brown and fuzzy. Not too appetizing.
(image online at http://en.academic.ru/dic.nsf/enwiki/147235)
But, in grapes, if the level of Botrytis is just right, you can make a very special wine called Botrytized wine, otherwise called “The noble rot.” Highly delicious!
'Hey - Did-ya Miss Me?' Anthacnose was plentiful in the UCR diagnostic lab this week
I was back in California this week and greeted with triple digit temperatures - normally I'd say the dry heat of California is better than the steamy heat of Washington DC, but 112 degrees in Riverside was still pretty bad!
I always say that anytime we get wide temperature swings, anthracnose is likely to rear its ugly head, and this last week was no exception - Naveen was getting quite a few of these samples in the lab.
As John had mentioned earlier this week, summer patch has been pretty active on annual bluegrass greens and we saw it on a few samples in California as well. Back in the 'good old days' of the 90's, it seemed like anthracnose and summer patch control went hand in hand, but recent developments have resulted in some 'complications'.
As we all know, anthracnose has become the primary concern of most guys out there with annual bluegrass greens, but summer patch can often be a hidden problem. Here are two observations regarding summer patch development this year.
#1 Targeting Anthracnose but Forgetting About Summer Patch
Sixty-five to sixty-eight degrees soil temperature in the spring is the magic range for initiating anthracnose & summer patch control programs with 2 to 3 applications of DMI-fungicides like Banner MAXX, Trinity, Triton, Tourney or Torque, but after that, control diverges quickly for these diseases. Fungicides like the Heritage (azoxystrobin) and Insignia (pyraclostrobin) are my top choices for summer patch control (thiophanate-methyl, e.g. 3336, is also a consideration), and should be applied monthly in the summer to keep summer patch in check. But....as we all know, anthracnose resistance to the QoIs and benzimidazoles in many locations makes these ineffective for anthracnose control. For mid-summer applications, products like chlorothalonil (Daconil), fludioxonil (Medallion), polyoxin-D (Endorse/Affirm) and Signature (Fosetyl-Al + StressGard pigment) are my go to materials. DMIs can also be effective, but applied in the summer heat may cause some unwanted PGR effects.
Superintendents worried primarily about anthracnose may be applying anthracnose-fungicides but forgetting to use Heritage & Insignia on a monthly program. As a result, summer patch can break through what seems like a good program that is unfortunately tailored specifically for anthracnose.
#2 Compass vs Insignia in Rapid Blight Control Programs & Effect on Summer Patch
Rapid blight is another disease that California superintendents battle in the spring and summer, and Compass (trifloxystrobin) and Insignia are the 'go to' systemic fungicides for rapid blight control (mancozeb is our only contact option), but differ in their physical properties. Compass is very strong as a foliar fungicide, but less systemic than Insignia and will not give you effective summer patch control. If you've been using Compass regularly in the summer, remember that you could be under-gunned for summer patch control, and have to apply additional materials.
Bottom Line: Anthracnose, summer patch and rapid blight management require specific fungicides - choose wisely and know what fungicides won't give you any overlap in disease control.
Anthracnose Rescue Fungicide Programs
If you have anthracnose breaking out on greens, it is most likely that you (i) have had a serious stress event, (ii) are too lean on fertility or (iii) have had a lapse in fungicide protection in your program.
Notice that 2/3 of the 'issues' are not fungicide-related. Correcting cultural practices and fertility is the top priority, but here are some thoughts on a 'rescue' program for active anthracnose outbreaks.
1. DO NOT BOMB IT WITH QOIs/STROBIES OR T-METHYL FUNGICIDES EVEN IF THEY STILL WORK FOR YOU. That is a recipe for resistance, big time! Anthracnose is already a high-risk pathogen when it comes to QoI and benzimidazole fungicides, and using them as 'eradiciants' in this way increases the chance of selecting out resistant populations.
2. CHLOROTHALONIL IS YOUR FRIEND. This is partially why I encourage guys to save up some of your 10 or so chlorothalonil applications for the summer. Chlorothalonil will not 'cure' existing infections, but can kill spores developing in acervuli and prevent new infections (if you let your foliar anthracnose go all the way in to the crowns, you're hosed, don't wait til that happens as you won't be able to get on top of it with fungicides in the summer). Being a contact fungicide, you will need to apply frequently to ensure that you have lasting coverage on plants. Applying the normal label rate, at a shorter application interval, is likely more effective than the max. rate once or at longer intervals.
3. MEDALLION, ENDORSE & AFFIRM --- These are 'limited systemic' fungicides and can give you added control of anthracnose, but are at moderate risk for fungicide resistance. I would not encourage them to be used as 'eradicants' but you can apply them to help with protecting plants once you have the active outbreaks arrested with aggressive chlorothalonil use. Right now, there is no resistance to these, & we want to keep it this way for the time being.
4. SIGNATURE, ALIETTE, & PHOSPHITES --- These have for the most part, 'indirect effects' on anthracnose, and will not work as 'eradicants'. The data I've seen shows that the active molecule in these fungicides is not super-toxic to anthracnose, and provide protection via induced plant defenses or other mechanisms; and you guys know how I feel about StressGard pigment being a good thing for annual bluegrass in the summer. Tank mixing them with your chlorothalonil will give you added protection but they will be acting on healthy plants vs. new infections and not directly killing the active anthracnose.
F-Bombs, Nematodes and Cee-Lo
Ok - I've gotten some (for the most part) good natured ribbing from some guys this week about my comments on Turf Net regarding what we know about nematodes.
Call me crass, but the F-word is strongly correlated with the discussion of turf diseases; it's one of those words that in its various forms has use as a noun, verb or adjective, especially when discussing anthracnose, summer patch or rapid blight, and annual bluegrass in general.
On the other hand, in all seriousness regarding the comments, we really don't know enough about nematodes on turf, and really really don't have enough chemical controls for the problems - making me drop the F-bomb to drive home the point.
Compared to the 30 or so university turf pathologists in the US and dozen or so different fungicide active ingredients, we have like 4 turf nematologists (Crowe, McClure, Wick & Mitkowski come to mind) and 1 nematicide (Curfew), plus any Nemacur stockpiled in the shed, that can control nematodes down in the soil .
You know I love me some fungus, but considering the issues caused by nematodes like root knot, stem & gall (Anguina), spiral, sting and others, and more importantly - the high amount of "mis-information" about nematodes and their control out there - it's a good time to put some attention and funds towards this. That's my 2% of a dollar.
Finally, if you can't get enough of the F-Bomb, check out Atlanta-based Cee Lo's new music single and song here:
(WARNING: DEFINITELY NOT SAFE FOR WORK OR CHILDREN)
If you're not offended by the F-bomb and like Old School Motown-Style R&B, it's certainly worth a listen. I suspect they will have taken this one down from the internet by the time you read this blog today, but I'm sure you'll hear about this one soon.
OK - Back in DC as of the Morning and Signing off from the Right Coast.....
This week’s cooler, dry weather has shut down most of the diseases we have dealt with this summer. I don't know this for certain for every location in the Midwest, but I do know that my phone was very quiet the last few days. We still are getting samples of Poa annua crapping out either from heat stress or summer patch or a combination of both. This was an exceptionally difficult summer for golf course superintendents. Most the turf loss this year was due to heavy rains in June and July coupled with high day and nighttime temperatures. Soil temperatures in many locations I visited exceeded 95F, which is not a good growing environment for any cool-season grass to say the least.
The major lesson I learned this summer was the importance of establishing a written set of maintenance and playability standards. By putting categories like day-to-day green speed, firm, fast or green, lush gives the golf course superintendent a lot of flexibility. For example, a hypothetical course has established a maintenance standard of 9 foot green speeds every day. By simply stating this standard allows the golf course superintendent to vary practices to achieve this ball speed. Viable options would be alternating mowing and rolling, switching to smooth rollers, and raising the mowing height in an attempt to minimize turf loss. I do understand that setting maintenance standards may not work for each situation, but it may be something to try especially at a public play facility. You may think I am crazy for talking about this, but based on my observations this summer establishing a set of maintenance standards seemed to work.
This is also the time to start thinking about snow mold applications. Here is a link for our snow mold trials for 2009-2010. The key with these reports is to look at the treatments that provided the best control (lowest disease severity) at the site closest to your site. We test a wide variety of chemicals and combinations at five locations in order to provide golf course superintendents with a plethora of options. We do not distill the reports down to the top ten best products because the best products and combinations may not be within the budget of many golf courses. So we always recommend finding the product or products that provide the best control and fit within the constraints of your budget.
Timing of snow mold fungicides was a fairly hot issue early this spring, largely due to some perceived failures of very good snow mold fungicides. We still do not have a great answer, so are initiating a fairly large fungicide timing experiment this fall. We expect to see good control from systemic products when they are applied well before snow cover, and good control from contacts closer to snow cover. We will let you know next spring, so stay tuned.
|I'm still hearing a lot of reports of active summer patch.|
Despite weather changing for the better and growing conditions improving, this is presenting a problem for some as the turf that made it through the summer is starting to look good which is making the turf that was on the edge or that didn't fair well look even worse. Regardless, now is the time to overseed and start getting that grass back prior to winter.
I have also heard of some that have shut down their greens or entire course in the last week or two. The overcast and wet conditions in some areas appears to be giving rise to bacterial wilt problems on annual bluegrass. Since legal control measures are limited to non-existent, it is important to raise mowing heights, dedicate a walk-mower to affected greens, mow when it's dry, and wash equipment with a 10% bleach solution to help reduce the damage. Aggressive cultural practices like topdressing and aerification should be avoided during this times too which may cause problems for some since the calendars may be fixed for these activities to take place.
|Brown patch on a new putting green seeded in June.|
Other than that, things are starting to get a little more quiet and I see that the chatter of mid-summer is dwindling to a mere whisper. It is almost time for a much needed break and a cold one...you deserve it!
Strong storms caused some major tree damage last week. One golf course had some very large trees become uprooted, crashing down on across the fairways. Gusts of 90 mph were recorded (!)
A few days after the storm it was remarkably cool. After visiting my field plots on Tuesday morning, I needed some HOT tea instead of ICED tea.
The volume of turfgrass samples is way down this week, too. I hope everyone is enjoying the slight break from the stress.
To make up for the turf, I have had other types of samples including a smelly bag of pumpkin goo:
There wasn’t anything I could do with that one, other than hold my nose, throw it away, and ask for a new sample.
Dollar spot is on the rampage in some of our research plots, with infection centers coalescing and becoming quite sunken. The photo above shows infection in an untreated plot of a Cato-Crenshaw blend (very susceptible). In another week (or two…) I’ll try to summarize some of the data from our summer trials.
In the trial in cultivar A4, the dollar spot severity is hanging at about 10% (click to enlarge):
Brown patch is very active on the research greens at Rocky Ford:
The photo doesn’t quite do it justice–if you look closely (click to enlarge) you can see it better.
What else is going on out there?
Too bad we can’t eat nutsedge:
“sedges have edges” (note the triangle shape)
Too bad we can’t eat spurge, either
I guess if it came down to it, we could eat this guy:
Deep fried, crunchy. Lots of protein.
Email received about my post about the WSJ article:
"I recently read your blog titled “Melting turf and Turf Pathology meeting”. And I was a little confused on some of your statements. In the blog you stated your read the article in the Wall Street Journal. Then you later state some diagnosis was BS. Were your referring to something in the WSJ article was BS or was that an entirely different matter? I am not questioning you, just trying to clarify what you meant because when I read your blog it came across you were saying the WSJ article was BS. Which I hope wasn’t the case as that article has definitely helped me in my current situation."I thought that the WSJ article was a great one and anytime the popular press covers an issue like turfgrass being hard to maintain due to the heat of the summer, I think that it is good for superintendents. The issue related to BW was totally separate and had nothing to do with the WSJ article. In my follow up to the email I also mentioned some errors in the article, but when I went back and read the article I realized I was talking about an article posted by Lane in a previous post where they called Pythium a bacteria.
Email received about my post of bacterial wilt being BS:
"Wow John, doesn’t sound to Scientific! Better start doing some research to make a real Diagnosis. I was at APS also, you should have come by if you needed validation. [sentence omitted for privacy]
Explain the Etiolation please, sounds like Penn State might be rubbing off on you. Lane still can’t explain why healthy plugs die in three to five days. If he has to you please let me know. Heat and Humidity right???? Hope you aren’t teaching that."So my response to this was probably a little harsher than it should have been and I realize that superintendents are under a lot of stress. I also don't take anything personally and do my best to try to help any way I can...and yes, I love Penn State (this happened long before I took the job here though). However, this brought up a good point about the whole bacteria wilt issue. I am not saying that a potential bacterial wilt problem doesn't exist, however, I feel that many diagnosticians and superintendents are using this as a go-to answer for problems that can't be explained. In many cases (generally about 35-50% of our samples annually), thinning and/or dead turf can not be attributed to a biological agent. That doesn't mean that something can't be done, it just means that spraying a fungicide is not going to be the answer. In many cases, the issues are related to shade, poor air movement, poor drainage, etc. Addressing these issues often times fixes the declining turf problem. A problem with many diagnostic labs is that they know diseases and diseases only...finding a lab that knows something about turf and agronomics is important. Click here to see all the comments regarding diagnostic labs.
|Dollar spot was raging this morning in State College, PA|
Temperatures are dropping around the mid-Atlantic and Northeastern US, but this may actually bring more diseases than less. At the turf plots this morning at Penn State, we had active mycelium on both dollar spot and brown patch, algae raging, anthracnose active, red thread in low fertility areas, and probably other things that I didn't have a chance to check out. I also received an email while typing that a superintendent in the area may have a new outbreak of brown ring patch on their greens. Temps in State College were relatively low this weekend, but RH was very high and things exploded last night. I am sure that many of you are experiencing the same thing in your region.
Here is the 10-day forecast for some cities around the region:
Albany, NY: mid 70's to mid 80's
Boston: Low to mid 80's with temps dipping to 77oF on Thursday!
Philadelphia: ~90oF for the next two days then mid 80's
Pittsburgh, PA: 77-85 with nighttime temps in the mid 60's/low 70's
New York: Temps ranging from 80 to 91oF
Washington, D.C.: Fluctuating between mid 80's and 90oF
Finally, I am working on our Compendium Giveaway and should have something up by next week. The giveaway is being sponsored by Syngenta and will give a reader the opportunity to win a copy of the Compendium of Turfgrass Diseases. Syngenta will also be donating $1000 to the Turf Pathology Student Travel Fund of the American Phytopathological Society.
When I got back to town late Wednesday afternoon I found a few turf samples waiting, and a few more rolled in Thursday and Friday. More of the same--steam-cooked roots.
Wow, you know, there's been so much chatter about bacterial wilt that I don't have much more to contribute. I'll just say that I, too, feel that it is important to be skeptical. If you've missed the BW discussions, scroll back through the blog and be sure to read the comments at the bottom.
Stress tips from USGA
The following link has some comments and tips from USGA agronomists:
Here’s an excerpt, and you can go to the link for the full info:
“It is important that golf course superintendents use defensive golf course maintenance programs. That is, be conservative and pamper the grass. The turfgrass is under intense weather stress, which is compounded by an increase in disease pressure. Everyone should be more concerned about plant health than green speed."
I spent Saturday through Wed at the national plant pathology meeting in Charlotte, NC. What do we do at these conferences?
The main thing is to exchange ideas about research. In human medicine, there’s a lot of behind-the-scenes work at medical schools, research institutions, etc, before things reach practical day-to-day doctor’s offices. Plant pathology is the same.
*How do bacteria secrete proteins into the plant to allow infection to occur? How do those proteins change gene expression in the plant? How can we develop plants that can defend against these bacterial proteins?
*How do viruses move around within a thrips (insect) before getting transmitted back to the plant? Is there a way to prevent this from happening?
*How can we use DNA sequences to more efficiently identify resistance genes?
In the turf world, we had a whole afternoon dedicated to new (and tricky) diseases of turf caused by organisms in the genus Rhizoctonia. Now that we have better DNA techniques, some things we thought were true in the past are being called into question. The speakers in this excellent symposium were Phil Harmon (FL), Frank Wong (CA), Bruce Martin (SC), and Brandon Horvath (TN), and it was moderated by Jim Kerns (WI).
These are just a few of the types of things that we do.
On top of that, we have committees that do things like:
- work with K-12 educators to help enhance science activities in the classroom
- assist colleagues who are researching important disease problems in developing countries with the hopes of increasing global food security
- work with graduate students to help them find appropriate career tracks
- work with the chemical industry to discuss ways to mitigate fungicide resistance
It seems that John's post on Monday has caused quite the stir amongst the followers, but he is exactly correct. This is not a "calendar year"! The summer has sucked for most superintendents throughout the US. Grass is dying everywhere and the typical actions like raising the mowing height, alternating mowing and rolling, and other techniques are not helping like we'd like. I think the MOST important thing for golf course superintendents to do is start a line of communication with the owner, membership, golfer, general manager about losing turf. Regardless of the reason or diagnosis this is a banner year for losing turf.
For anyone that knows me I am not a pessimist, but when soil temperatures are above 90 degrees turf is going to have trouble. These temperatures can lead to disease development especially with the amount of rainfall we have had in the Midwest. However, many times grass just dies due to abiotic conditions like poor drainage, anaerobic conditions and heat stress. Remember that annual bluegrass and creeping bentgrass are cool-season grass and prefer to grow when soil temperatures are between 55 and 75 F. Not 90 to 100 F! Lets face it even bermudagrass will struggle when soil temperatures exceed 95 F.
Regarding bacterial wilt, a turfgrass system is a very dynamic biological entity. Many microbes inhabit the rhizosphere of turfgrass plants, which can make turfgrass disease diagnosis extremely difficult. In almost every sample that comes through the TDL, we can find numerous turfgrass pathogens. Furthermore the scientific community is finding that many bacterial species are common epiphytes (live on the surface of leaves) and endophytes (live inside the plant). That being said, it is very common to find bacterial streaming from stressed turfgrass plants. However the signs need to match the symptoms observed in the field and it seems like these two are not jiving.
In my humble opinion, it seems like bacterial wilt has become the perfect fall guy for a brutal summer. It's perfect because it is a mysterious disease with very few effective control measures, but we also have very few control measures for nature.
Summary of a Presentation from APS:
This year's APS meeting was great! Some of the turfgrass pathologist got the opportunity to visit a few golf courses in NC. I was amazed on how quickly I have acclimated to the summers of Wisconsin, damn its hot down there! I really did not have a favorite presentation at this year's meeting. I think the most interesting aspect of the meeting was a special session on Rhizoctonia diseases in turf. There was some fantastic information presented ranging from taxonomic considerations for this genus, biology and management of brown ring patch, management of leaf and sheath spot of ultradwarf bermudagrasses and finally using digital imaging software as a tool to score and identify host resistance in turfgrasses. There was so much information in this session, but the best part was how collegial the speakers were to one another.
Each speaker reference each other and it seemed that they were all working together to help fill in some major gaps with the Rhizoctonia and Rhizoctonia-like diseases in turfgrass. It is cool to be a part of this group, all of my colleagues are extremely helpful and willing to collaborate on projects. As a result, I think we will see many enigmatic problems in turf solved fairly quickly.
Summary of a research project.
Well, I was supposed to summarize a research project that was talked about this week, but the only turf talks so far were on Sunday afternoon at the same time as my meeting for the APS/Plant Management Network Oversite Committee that I serve on. So I missed all the talks. I will say that I heard good things about the talks from the various graduate students and I look forward to seeing the posters tonight. Tomorrow is the big Biology and Management of Rhizoctonia Diseases of Turfgrass, so I am excited to listen to a few of the talks being presented there. To read some of the abstracts related to turf, you can search here.
Brown, mushy roots:
And, sometimes Pythium oospores (stained pink here):
In the diagnostic lab it has kind of been like that movie Groundhog Day, where each day brings a remarkably similar set of turf plugs.
The stress continues. In the Kansas City area it is still hot with rain, in other parts it is hot and dry. A superintendent over in Kansas City told me that he had recorded a 2-in soil temp of 101. Yikes!
Jim had a nice post this week about the different types of Pythium, and there definitely have been some questions around here. So, if you need some further clarification I suggest reading Jim's summary.
Gray leaf spot
Gray leaf spot is the other big nasty disease on people's minds. There have been reports of GLS showing up early in states farther east, so superintendents in this area should definitely be thinking about it, scouting, getting on their spray programs.
Below is an image of GLS damage in 2007 that was sent in by a superintendent (I cropped it some for anonymity). The plants that are green are weeds (not perennial rye). In this case I believe they re-seeded with Kentucky bluegrass to avoid future problems with GLS.
Turf field day:
We had our annual field day yesterday. Thanks to everyone who came, and to the vendors for supporting this event.
The early part of the crowd mills around at registration:
One of the groups looks at a moss study on one of the putting greens:
I've had some turf samples come in packaged in unusual ways. Here is some turf packed in club-house towels:
There were 5 towels! My Christmas shopping is halfway done!
And another came in a box for Jessica Simpson sandals. Very sassy!
My two favorite boxes of all time are 1) a box from a 12-pack of beer and 2) a box that said "Quik Taters" (some kind of frozen potatoes).
So why are Pythium diseases problematic when the temperatures rise and relative humidity is through the roof? Pythium species are members of the Oomycota, which are commonly called water-molds. These organisms used to be classified as true fungi, but morphological and molecular evidence show that members of the Oomycota are more closely related to diatoms and brown algae. Yeah I know you don't care, but I do believe in the quote from The Art of War by Sun Tzu- "Know thy enemy and know thy self and you will win a hundred battles." It is vital to understand the pathogens you fight on a daily basis.
We have seen a number of different diseases induced by Pythium species, such as Pythium blight, Pythium root rot and even Pythium root dysfunction. However, the symptoms, signs and conditions favorable for disease development are different for these three diseases. Considering the recent weather conditions, I thought it would be good to review the differences between these diseases as well as the management strategies.
Pythium Blight- This disease has been the subject of nightmares for golf course superintendents for years. The fear most likely steams from the days when Pythium aphanidermatum developed resistance to metalaxyl and entire fairways were wiped out rapidly. Today we rarely hear of entire fairways devastated by Pythium blight, but the disease can develop even the Upper Midwest. However, the development is typically centralized around a drain or low lying area. If the disease is not controlled and hot, humid conditions persist the disease could spread at an alarming rate. Usually we only have 2 to 4 weeks of heat and humidity conducive for Pythium blight development in the Midwest, yet this summer has been a bit different than normal.
The symptoms of Pythium blight start as small, gray spots that can coalesce into larger areas of blight fairly quickly. Typically development of this disease will occur around drains or low lying areas of fairways. The picture just above the heading of Pythium blight is typical of the symptoms we see on creeping bentgrass in the Midwest. Cottony, white mycelium may also be present during early morning hours when dew is present. As for management, its a good idea to start thinking about Pythium blight when nighttime temperatures are above 70 to 75 degrees and when there is plenty of soil moisture. Fungicides that work best are Subdue MAXX, Stellar and Segway. Other products that may have varied results are Banol and Terrazole. Keep in mind that Signature works, but only when pressure is light to moderate.
Pythium root rot- Pythium root rot can be a major problem of golf course putting greens when there is persistent heat, humidity and low light intensity. This disease is also a problem on putting greens with limited air movement. One of the major problems with this particular disease is we know very little about the pathosystem. Consequently most the control recommendations are based on observations made by golf course superintendents. I think Lane posted about Pythium root rot sometime last summer and talked about the issues surrounding this disease.
The symptoms are usually diffuse, irregular areas that exhibit decline. The affected areas can decline quite rapidly because the pathogens destroy root tissue. The picture above is an example of typical stand symptoms. A noticeable decline in root depth is usually observed within affected patches. If you suspect Pythium root rot is an issue at your course, I suggest sending a sample to your local turfgrass pathologist for confirmation. Usually the best medicine for Pythium root rot is a Terrazole drench. Unfortunately, this disease can still develop even if you are on a good Pythium preventative program. Remember that most turfgrass fungicides only move up from the point of absorption, so in order to get Pythium root rot activity the fungicide needs to be washed into the rootzone.
Pythium root dysfunction- I know this is confusing, but Pythium root dysfunction is a totally different beast that Pythium root rot. The conditions that favor Pythium root dysfunction (PRD) symptom develop are hot, dry conditions not hot, humid conditions. PRD shows its ugly head on upland areas and develops into a discrete patch. Normally this disease is problematic for young putting greens built with high-sand content rootzones. I have blabbed on for a while on this post so check out a previous post by Lane for PRD management strategies.
To bring this belaboring post to an end, if you suspect any Pythium induced disease have it diagnosed by your local turfgrass pathologist. These diseases should not be taken lightly and all of them have different management strategies.
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?
|Image from by greggoconnell|
Other diseases and anthracnose update.
In addition to the widespread outbreaks of summer patch, there have been reports of several other diseases including Pythium, gray leaf spot, brown patch, dollar spot, anthracnose, rust (in my backyard), and probably others. Just a brief update on anthracnose. Our research trials this year have been some of the best in recent history and there are several products standing out in the study. The new fungicide Torque (tebuconazole) is once again performing outstanding with less than 1% disease in plots as compared to the ~45% anthrancose in the untreated control plots. Also performing exceptionally well are Daconil (3.2 oz) + Signature (4.0 oz), Signature (4.0 oz) applied every 14-d in combination with Triton FLO (triticonazole) + chlorothalonil alternated on 14-d intervals, and several experimental fungicides. Moderate anthracnose suppression is being seen within plots receiving only DMI or chlorothalonil, which again shows the importance of tank-mixing these fungicides (they look great in the study when combined). On the flip side of things, the QoI chemistry is not holding up and there is likely resistance issues at our research plots at Penn State. Oh, and I almost forgot about the fertility plots. We have some fertility treatments in combination with Signature alone. Signature alone is providing about 25 to 50% control of anthracnose while Signature + the various fertilizers are providing about 60 to 80% control. So the take home message is to tank-mix and spoon feed to help suppress your anthracnose.
Spreading the word about the difficult year.
Both the USGA and GCSAA have put out their notices to golf courses describing the excessive heat and humidity this year. This is good information for members and greens committees wondering what in the world is going on. You can find the GCSAA's report here and the USGA's report here. The difficult thing for most golfers to understand is "why does our course look bad when I played next door and the greens are great?". Unfortunately, a lot of this can't be explained or not in a simple way. Most of the time the difference is sound cultural practices employed previously and not anything done this year. Those superintendents that were allowed to pull cores multiple times, install drainage on poorly drained greens, or selectively remove trees that were causing shade problems are the winners. It could, however, be as simple as explaining to members that your crappy Poa greens just won't hold up like the bentgrass greens at a neighbors.
I've seen a bit of anthracnose on Poa annua at Japan, damage from foxes and rabbits at England, from wild pigs at Japan (Figure 1), some hydrophobic soil conditions at Dubai, even some lingering large patch into June on Zoysia japonica in the mountains of Nagano, and red thread at Scotland in July. Fairy ring appears ubiquitously on all types of turf (see Figure 2 below). Now I am hearing of extreme weather and heavy rainfall at Singapore that is causing challenges to turf, along with extreme heat in North Asia that is putting creeping bentgrass under severe stress. That is all I have to mention about diseases in this post.
But I do want to share a few thoughts that I have had this summer, which I make bold to post here thinking a few people may be interested in a temporary diversion from the mathematical certainty of x + y = dead grass. And as I am writing this from Bogor, 6° South of the equator on the island of Java, I can claim, in an astronomical sense, if not a meteorological one, that it is winter here today. Thus, my Winter Notes on Summer Impressions:
1. A quote that seems particularly apt this year is this one, from the introduction to the book Practical Golf Greenkeeping, published at London nearly 100 years ago. "To my mind . . . the most impressive lesson any greenkeeper can learn, is the one acquired under adversity. The real science in greenkeeping is not to be gained where difficulties in maintaining the turf are never experienced. Practical tests in overcoming trouble of any kind are the best way to obtain knowledge.” Small solace perhaps, but as true today as it was a century ago.
2. I am becoming more and more uncomfortable when I hear imprecise terms and phrases related to golf course appearance and playability. Whether that be something about "firm and fast" or "brown is the new green," I find these terms to be imprecise and particularly susceptible to misunderstanding. I think of an article co-authored in 1916 by Charles Vancouver Piper, first chairman of the USGA Green Section, in which he wrote, "The function of language is to convey ideas. Unless the language is understood in the same way by writer and reader this function is not served and ideas are not transmitted exactly . . . It is becoming increasingly evident that the terminology of agronomy is not always clear."
Golf is a game. The physical characteristics of the playing surface are crucial to the enjoyment of the game, but these characteristics are not well-described by terms such as firm, fast, brown, green, or sustainable, unless those terms are put into some type of context, or are measured. The STRI Programme, which takes a quantitative measure of the performance of the playing surface at a golf course and puts a value on ball roll distance, surface firmness, surface smoothness, and other important characteristics, is a system for measuring these physical characteristics and can lead to the exact transmittal of ideas. I had a chance to work with the STRI tournament agronomy team at the Open Championship in July. After seeing this firsthand, and thinking about it as a golfer, former superintendent, and scientist, I am excited about the usefulness of the STRI Programme and the removal of so much ambiguity from terms used to describe golf course appearance and playability.
3. Does anyone else think that "corrective watering" is a particularly egregious term? I first heard this at the US Open in June, and this week read an article about Sahalee and the US Senior Open where the term was used again. "Corrective" implies that something was done wrong, that an error is being put right. Wouldn't "supplemental irrigation" be a more appropriate description of water being applied to the turf? If "corrective watering" is a term that should persist, maybe "disciplinary mowing" and "interventional rolling" could be added to this malapropistic vocabulary.