Turf around the country continues to decline and it looks as if there is no break in sight for some time. Many golf courses are having trouble and I even read a
Wall Street Journal article today that talked specifically about the problems courses are having. In the article it states that "a handful of high profile courses had already had to close, and if the heat continues, others are likely to follow." It goes on to mention a few of the courses by name which mean to me that the problem is so bad that courses are even trying to hide it at this point. On top of that, the whole issue of this bacterial wilt problem hitting bentgrass is raising all sorts of questions among pathologists. I can't speak for everyone, but the general feelings among those that I spoke with so far this week is that it is a BS diagnosis. I will leave that for later in the week in hopes that someone else will elaborate more.
This week is also the annual meeting of the American Phytopathological Society (APS) meeting in Charlotte. Several of us had the chance to visit a couple of golf courses down here during the trip and I gotta say that the bentgrass really is as bad as many have said on several courses (photo right). The stuff is just melting away. My caution to anyone in this situation down here in NC or throughout the mid-Atlantic and Northeast is to be cautious about your plans for aerification. This is definitely not a "follow the calendar" year in terms of planning aggressive practices on your greens...that is what happened to many last year and aerification at the wrong time can lead to some quick death. So, be cautious about planning these activities until you get some root growth that can hold it all together.
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.
11 Responses to “Melting turf and the turf pathology meetings”
I'm anxiously awaiting for you to elaborate on the BS.
I guess BS is a little strong of a word, but more like...the verdict is still out. We all agree that we can see streaming of bacteria in samples that are under a lot of stress, but there has been no studies or research that shows this streaming in stressed plants is directly related to any field symptoms. Basically, many of us are just as frustrated with the issue as many of you. However, there is still no proof that these field symptoms are caused by the bacteria. This doesn't mean that it's not bacterial wilt, but it just hasn't been proven yet. On top of that, once this BW wilt issue started to spread, every golf course mysteriously got it. The bottom line is that it becomes a scape goat for any problem that can't be explained. In my mind, a diagnosis of "negative for disease" is a legitimate one but not an answer that many superintendents like to hear because it's a hard one to find a fungicide for!
One of the problems with the current state of turfgrass diagnostics is that we are willing to provide a "no pathogen found" diagnosis without figuring out the cause of the turf stress that resulted in a the superintendent sending the sample in. Diagnosticians should be able to provide a complete diagnosis - the most likely cause (biological, chemical, environmental, etc.), a recommended treatment action, if any, prognosis for recovery, and prevention in the future. The reason we don't provide complete diagnoses is due to the low fees charged for a diagnosis - we can't afford to provide a complete diagnosis for $100-$150 per sample. Want to get rid of some of the confusion in diagnostics, charge what a diagnosis really costs and run additional lab tests to get a final answer. No pathogen found is not a diagnosis - in my opinion.
Larry Stowell
Regarding samples. I'm sure some samples are being sent to a broad spectrum plant disease clinic.
They will accurately give you a disease report. But they do not really know and understand turfgrass. They will not have the practical knowledge nor agronomic experience to pin point a specific stress problem.
It might be a struggle for even a turf disease diagnostician to pin point specific stress problems with a few plugs of turf. That would require a much bigger picture.
It's easy to spot thatch or a poorly draining soil condition. But what about the well draining sand green with no excessive thatch that is thinning out and is not responding well to cultural practices and fertility inputs.
Now picture a plug of that turf sitting on your desk. Good luck figuring that out if there isn't a pathogen present.
But I do agree that stress related problems should be looked at with the same enthusiasm as looking for diseases and any helpful information should be provided even if no conclusive diagnosis is available.
Many of turf literature state the "bacteria fog" is the available diagnostic method for BW. Are you saying the streaming bacteria in the lab is merely puffs of steam from over cooked grass that may or may not exist in the field? If that is the case, would it not seem reasonable to think all pathogen diagnosis is potential BS? Help me understand this.
The problem is that there are a lot of bacteria on and in stressed and dying turf. Cut open a turf plant that's been killed by heat, disease, Roundup, or anything else and you're likely to see some bacterial streaming.
As an example, last year we had a sample of bentgrass into the clinic that we saw streaming in. Upon further investigation with the superintendent, we were able to confirm with 100% certainty that it was a case of herbicide injury.
Which brings me to my next point since we are talking about disease diagnosis. Most reasonable people would agree that you should visit the golf course in person before describing and publishing a new disease. However, those who published the paper on bacterial wilt in bentgrass didn't bother to do that.
As I said before, in order to diagnose a case of bacterial wilt, you have to identify the bacteria that is present in the turf and match it up with characteristic symptoms in the field. Without that, seeing bacterial streaming doesn't mean a thing.
A number of excellent turf pathologists are working to get to the bottom of this issue. If you suspect that you have bacterial wilt, or have had it diagnosed by a clinic, find someone who will isolate and identify the bacteria. This will help us all in trying to figure out what is going on here.
Bacterial wilt is difficult to diagnose with any level of confidence for most diagnostic labs. Last year I encountered a case that looked pretty solid for a bacterial wilt diagnosis. I isolated several bacteria and Dr Frank Wong and Dr Naveen Hyder isolated a few different bacteria. Frank and Naveen followed up with identification using DNA technology in addition to pathogenicity testing - none of the isolated bacterial strains could be induced to cause disease in greenhouse conditions. Four or five months later, we conceded that the primary cause of the turf damage was most likely heat and drought stress and the bacteria finished the job. Would the turf had survived if the bacteria had not rapidly colonized the damaged tissues? We just don't know yet. Until we learn more about bacteria associated with turf, bacterial wilt is likely to be "over-diagnosed." Unfortunately, you just can't validate a bacterial wilt diagnosis in a short period of time. Maybe it is best to implement as many bacterial wilt management practices (largely stress recovery tactics) as feasible even if you know that the bacterial wilt diagnoses are not very accurate - yet.
Dr. Stowell makes a great point. The problem is that people will often take drastic, and sometimes illegal, steps to kill bacteria after receiving a diagnosis of bacterial wilt. Sometimes these applications do more damage than the bacteria itself!
Drastic times call for drastic measures particularly if a course manager has tested for all potential pathogens with no success. Adding to their confusion is they have adequate perk rates, moisture levels, nutrient levels, and so on. As such we can see where many are grasping onto the BW diagnosis.
Sometimes the plant just dies from a complex of extreme environmental conditions.
There is only so much you can spray and pray.
A friend passed along this discussion so I thought I would contribute. I don't usually have the time for online debate but since John has decided to decry bacterial wilt as BS, I guess I have to respond.
In the past two months I have seen lots of bacteria streaming from bengtrass. Some of it seems to be doing significant damage, some of it seems to be doing nothing more than causing etiolation. And some of it is saprobic, coming out of dead tissue.
I have no doubt that bacterial wilt of bentgrass is a bonafide pathogen, however, the question that remains is the nature of its pathogenicity. Is it in fact a primary pathogen, like dollar spot, that is being stimulated by the high heat (its optimal growing environment) or is it a secondary pathogen that is attacking plants that are already severely heat stressed.
Vargas demonstrated that Acidovorax can kill turf in a greenhouse. The Japanese also did this. So there is certainly proof that a bacteria can cause wilting and death of bentgrass. Whether the presence of streaming bacteria in bentgrass is always causing symptoms on a golf course is debatable.
It does require more research but to call it "BS" seems a little extraordinary.
To claim that "every golf course mysteriously got it" seems far fetched to me. In the month of July, I received a record 400 plugs from at least 150 courses (I'll officially tally the numbers when the samples stop coming in- it's a Monday and I have 8 waiting for me now) but of those 400, less than 10% were submitted with an indication that the superintendent thought it was bacterial wilt and it was present in less than half of those.
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