So, can we all agree to call it yellow etiolation instead of just slapping another erroneous name on it? I know that 'etiolation' is difficult to pronounce, but you can hear its correct pronunciation and practice along at thefreedictionary.com/etiolation.
Early on, I had a theory that biostimulants and/or growth regulators were involved in either causing this yellow etiolation or increasing its appearance. I wanted to share a couple of pictures recently sent to me by golf course superintendents that provide even more evidence of their role in this condition.
This first picture was taken at one of our research sites. Our plots were positioned in a ring around the cleanup pass of this green, and we asked them to avoid spraying our plots when they made certain applications to the greens. The area to the right that is declining severely received their sprays containing a biostimulant product and the growth regulator trinexapac-ethyl. As you can see very clearly, the areas NOT receiving these sprays are much more healthy than the areas that were sprayed.
This second picture was sent to me by a golf course superintendent in Pennsylvania. You are looking at a collar-height walkway between a green and a tee. The area to the left of the red dotted line received double applications of Primo, one along with the greens applications and another along with the tee applications. You can clearly see that the yellowing, etiolation, and thinning of the bentgrass is much more pronounced in the area receiving higher rates of Primo.
So what is going on here? To me, this is looking more and more like a physiological condition rather than a disease problem. We are still unable to consistently isolate any single pathogen, bacteria or otherwise, from turf exhibiting these symptoms. We are planning research to look at the influence of growth regulators and biostimulants on this problem. Until then, I suggest that superintendents who are battling this problem eliminate biostumulants from their programs and also avoid use of trinexapac-ethyl during periods of summer stress.
There still has to be more going on than this, it seems to me. I have seen etiolation from New Zealand to CA to NC, on poa and on bent, in environments ranging from cool temps and low light to hot with excessive sun, even without growth regulators and/or biostimulants. And, of course, there are lots of Superintendents using growth regulators and/or biostimulants who don't suffer etiolation.
ReplyDeleteOf course, growth regulators and biostimulants are not the total answer. But bacteria aren't the total answer either. As I said in the post, we are not able to consistently isolate pathogenic bacteria from bentgrass that is expressing these symptoms. This is a critical first step in characterizing a new disease problem, so we still can't say what the cause is.
ReplyDeleteRather than jump to conclusions and blame bacteria, we are trying to identify management factors that induce or encourage this problem. In some cases the symptoms are severe and persistent, in others it's a curiosity that comes and goes. What we're noticing is that the superintendents who use a lot of growth regulators and biostimulants are the ones that are having the greatest problems. The pictures speak for themselves.
I agree on your last post... growth regs and bios are not the total answer, if an answer at all, and neither is bacteria. As a senior (read old) GCS, I have used both for years without problems and friends who use one or none have had real bad issues. We have humidity, varying temps, sharp mowing reels, dull mowing reels, various uses of fungicides, sun, clouds, etc... sometimes a course just 2 blocks away can be a world away when considering all of these factors. Not sure how we landed on growth regs and or bios given all those factors but then again I don't have a PhD. Let's see some data nonetheless so I can sleep at night.
ReplyDeleteYou're not sure how we landed on growth regulators or biostimulants? Read the post and look at the pictures. These are just two specific examples where I was confident that they were exacerbating the problem. There are many other examples I could point to.
ReplyDeleteI understand that many different factors can influence turf health, after all, I am a turf pathologist. I've taken all of the factors you mentioned into account and many more and that's how we 'landed' on growth regulators and biostimulants.
I don't pretend to have this all figured out, and I don't have data to prove to you that growth regulators or biostimulants make this problem worse. I do see a lot of golf courses in my work and based on what I have seen I strongly suspect that they do.
My job as an extension specialist is to help people who have a problem. If you have this problem and ask for my recommendation, I will suggest that you eliminate biostimulants from your program and also lay off growth regulators during summer stress. If you don't have this problem or don't want my recommendation then keep doing what you're doing.
From a research standpoint, we are working very hard to get to the bottom of this problem. Everyone on my full-time staff of 5 is putting significant time into this project. We have been isolating and identifying bacteria in every bentgrass sample that comes into our clinic. We ran all over the state this summer to evaluate antibiotics and other materials for bacteria control. We have research in the ground right now to look at these biostimulant and growth regulator interactions. Trust me, nobody is working harder to get data to prove what is going on here.
In my experience I have only seen this in wet soil under heat stress or when it's been wet and cloudy for many days. The have never seen this phenomenon occur on turf in Missouri when the turf is dry,even when using Primo and biostimulents. I believe the problem is too much water and the turf in the pictures look wet
DeleteLane,
ReplyDeleteAre you doing controls with PGR alone and biostimulants alone to try to determine their relative influence? Is it all PGRs or just TE that's suspected? Is it all biostimulants or just those with GA?
thanks.
Yes, we are looking at growth regulators alone, various biostimulants alone, and combinations of the above. It's hard to say if it's GA or other compounds as the contents of these products is not always clear.
ReplyDeleteAre considering growth regulators with specific biostimullants. I am particularly interested if you have any data with the Vitazyme biostimulant.
ReplyDeleteWe are in the preliminary stages of researching the effects of growth regulators and biostimulants on etiolation of creeping bentgrass. Vitazyme is not one of the products I've run across, however, so we are not working with it at this time.
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