[Dave_Miller]

To the Treehouse:

Having a conversation yesterday with our Green Chairman concerning thatch and the impact it has on the playability of Greens on the course.  

We realize that thatch holds water and can cause approaches and Greens to be soft but is there any other negative or positive influences from thatch and thatch build-up.

Does thatch or the build-up of excessive thatch have an impact on Green speeds?

Does thatch make Green speeds slower, faster or have no impact?

If anyone, especially you Supers out there, has any information they can share on this it would be greatly appreciated.

Fairways and Greens,
Dave

[A_Clay_Man]

Dave- You will get a complete account from our resident helpful super supers. I'm under the impression that thatch allows among other undesirable things to occur, a fungus medium.

[DPL11]

Dave,

Thatch in excess of 1/2" in greens will affect green speeds and overall health. The general rule is the more thatch, the slower the surface. Most supers perfer the minimum amount, but much depends on what grasses are being grown.

Bentgrass and bermudagrass are both heavy thatch producers, but certainly maintainable. The biggest problem,is that once you have excessive thatch, you need to be very aggressive with verti-cutting and topdressing to correct the situation.

[Dave_Miller]

Dave,

Thatch in excess of 1/2" in greens will affect green speeds and overall health. The general rule is the more thatch, the slower the surface. Most supers perfer the minimum amount, but much depends on what grasses are being grown.

Bentgrass and bermudagrass are both heavy thatch producers, but certainly maintainable. The biggest problem,is that once you have excessive thatch, you need to be very aggressive with verti-cutting and topdressing to correct the situation.

Doug:
Thanks.
Our Greens are primarily Poa but we have been seeding with Bent Grass the last four years.  Would this be a cause of excessive thatch buildup.
Best
Dave

[Donnie Beck]

Dave,

A little thatch is good, but too much causes all kinds of problems. Too much thatch will cause soft spongy greens, but more importantly it affect the way water enters the soil. The thatch layer will cause somewhat of a purged water table. The entire thatch layer will have to become saturated before the water will enter the soil below. This causes a very shallow weak root system that will leave the plants suspect to more insect and disease pressure. Too much thatch will also increase the probability of mower damage. The thatch accumulation is a never ending battle. It is going to take quite a while to correct the problem. It is going to take multiple aerifications with heavy topdressing. I would also recommend starting a bi-weekly light frequent topdressing program. The light frequent program is going to have some budget ramifications due to extra labor and reel maintenance. If you would like some more information feel free to call me at 631-788-7224.

[wsmorrison]

Donnie,
Sorry this is off-topic to this thread, but I was wondering if you got the materials I sent you?
Best,
Wayne

[Brian_Gracely]

How often do most clubs thatch their greens?  Is this done via verti-cutting or some other method?  How about the frequency of thatching green-surrounding areas?

[TEPaul]

From talking to Dave it appears Charles River's greens are in some serious need of de-thatching as he says the club's maintenance practices really haven't been doing it in far too long. The supers on here will and already have explained what the program is to remediate a thatch problem in the greens. Certianly there's some inconvenience to normal play (that's probably the real reason this has been deferred too long).

But one of Dave's questions is really interesting. Given some baseline cut height----let's say .135 of an inch---would a green putt slower at that VERY SAME CUT HEIGHT if it had loads of thatch underneath (soft) vs a green that was firmer and drier with very little thatch?

Unbelievable the answer seems to be yes!! The exacts and specific reasons why don't seem to be readily available on here, although from just talking to my super about it he says Penn State has been studying this specific question.

Apparently even at the very same cut height, a really thatchy green creates some kind of resistance or additional friction to the roll of the ball compared to a firm, dry, dethatched green at the VERY SAME CUT HEIGHT! My super says, unbelievably, the extreme could be up to 10%!! That would mean a firm, dry dethatched green cut to some baseline comparison number like .125 might roll at 10 on the stimp while the same cut height on a thatchy green would only roll around 9 on the stimp!

[W.H. Cosgrove]

I am green chair at my home club.  After years of low budgets thatch had built up on our poa greens to the point where they were very bumpy and as a result slow, despite mowing heights of .085 of an inch.

We are nearing the end of a very aggressive year of care for our putting surfaces.  We have done three major things.

1) We purchased a Graden Vertical Slicing machine and with the help of 90 hours of volunteer member labor we sliced all of our greens.

2) We purchased a Dakota Spinner/topdresser.  We are now able to lightly top dress our greens in just over 1 hour every other week.  The previous process took two men over 4 hours to complete.  As a result we had not been todressing as often as we would have liked.  The spinner has made a huge difference.

3) On alternating weeks we are grooming or verticutting the putting surfaces.  This reduces overall turf density.

Results have been excellent.  We are able to maintain green speeds of between 10 and 10.5 feet, the greens are much smoother/truer and we have manged to raise mowing heights from the ridiculous .085 to .105 of an inch.

Our super is concerned about the added stress from this muchcare but we hope the higher mowing heights will allow usto avoid disease.  Member complaints have dropped markedly.

We have urged patience at every step and communicated constantly.

Good luck

[TEPaul]

W.H.

I think some might say that if you were mowing at heights under 1/10th of an inch with a significant thatch buildup on your greens that someone might be somewhat misinformed about what the actual mowing height really was. My super told me just today that if he tried to mow his greens under 1/10th of an inch with real thatch in them (soft) he'd very likely run the risk of scalping the beejeesus out of his greens!  

[TEPaul]

Another factor to perhaps consider with actually mowing that low (.085) is the question of your bed-knives. At a cut height that low and lower they don't last more than one cutting, apparently. Up at Shinnecock the super mentioned when you get down to cut heights really low like that the bed-knives have to be so thin they may only last for 6-9 greens! And apparently bed-knives aren't all that cheap either! Do you know what the bed-knife is W.H.? Our green chairman didn't until about a month ago!

[Don_Mahaffey]

I'm with Tom on this one. IMO, any green with serious thatch, 1+ inches, is going to scalp at ultra low mowing heights. Speaking of mowing heights, because of mower types, roller types, gauges and the guy doing the measuring, comparing mowing heights from one course to the next is tough to do with any meaning. For instance, we mow our greens with a Jacobsen triplex with grooved rollers at .115, we do our clean ups with a John Deere walker with smooth rollers which we learned through trial and error to set at .135 to match the cut of the triplex. Walkers and triplexs don't cut the same just as differing brands, angle of bedknife and roller types all affect the actual height of cut. BTW, why would anyone ever cut their greens at less then 1/10 of an inch. You can certainly find speed through drying 'em down or rolling rather then seeing how low you can go. Just my not so humble opinion.

[Mike_Trenham]

How does thatch relate to grain?

We have a lot of grain in our greens but they do get nice and firm when we, the governor or God turns the water off.  They are also extreemly smooth and true.  When I say a lot of grain I mean a lot!  Picture a balding guy with a  combover.  

For a long time I found the amount of grain on our greens to be very distressing, until from this website I learned to view this as traditional and not a sign of lack of maintenance.  This acceptance also helped me become a better putter and learn that I just have read the grain and hit the uphill putts a lot harder.  Another side benefit is when you play a guest in a match they are often completely out of sorts.  

I am old school, I like blind holes and grain.  Thanks GCA.

[Joe Hancock]

Don,

Your opinion need not be too humble when it is sound in its reasoning. Lots of detail that I, for one, am glad you went through the trouble o typing out for our friends.

By the way...I forgot what thatch, grass and mowing even is!

Joe

[TEPaul]

Mike:

I really wouldn't know what the effects of excessive thatch is on the grain in a green (if I had to guess I'd say thatch is not conducive to grain).

I do know that HVGC is the only club I know of who had an aggressive program to actually return considerable grain to their greens and it seems the method they used, generally speaking, was to really dry their greens out and get those roots way down there which as I understand it encourages a very long (grain) and strong plant on top. Obviously they must verticut very little if at all to encourage that much grain but they probably aeriate (remove any thatch build-up) and topdress regularly---and of course irrigate very minimally.

[W.H. Cosgrove]

TE Paul.  Just reporting what gets reported to me.  You can bring the measurements up with the mechanic and the super, just bring your micrometer along.  And yes, I do know what a bed knife is, I have watched as the mechanic went through the process of grinding.  Fascinating stuff!  As far as wanting to mow below 1/10thof an inch, I believe the point of the post was exactly that.  The risks run at such low mowing heights is extreme.  This is exactly the reason for going to the extra work of reducing the thatch layer.  

That said,no matter what the actual mowing height is with our Toro Tri Plexes the process we have undertaken has improved the putting surfaces significantly.  I think you miss the big picture.  The major point is that with more topdressing and aggresive thinning, green speeds can be maintained with higher mowing heights and thatch buildups can be reduced. We have also achieved a truer putting surface.  Further added benefit should be the reduced risk of devastating disease.  

[TEPaul]

"I think you miss the big picture.  The major point is that with more topdressing and aggresive thinning, green speeds can be maintained with higher mowing heights and and thatch buildups canbe reduced. We have also achieved a truer putting surface.  Further added benefit should be the reduced risk of devastating disease."

W.H.

Not at all--I'm not missing that big picture at all. Matter of fact, that's precisely what we're doing right now. I simply asked the question about mowing thatchy greens at .085 to see if you're really sure the cut height was an actual .085. A couple of supers simply surmise a cut height that low on thatchy greens would seriously scalp them.

Not just that but mowing firm and dry and de-thatched greens at an actual .085 very well might produce an eventual stimpmeter reading of 12 to 13 if you also are into a rolling program. I just wonder if you want greens that fast or if your course's green slopes and contours can handle that type of intense playability.

We've determined through months of study that around 11, and no higher is our "maximum reasonable" greenspeed. That seems to calculate to a cut height of around 1/10th of an inch or just a little higher with our rolling program.  

[W.H. Cosgrove]

Tom,
Thaks for your response.
Excessive pressure from members concerning speed was exactly the problem.  We have in the past been able to push speed over 12, Washington Open 2001.  Only Jeff Coston was able to break par, -3 as I remember.  
We were no where near the 1 inch of thatch described by Mr.Mahaffey.  Just enough to cause softness through moisture retention.  What members didn't understand was that the softness of the greens was scrubbing the speed off the ball.  

End result is we are producing a smooth surface that the members love at 10-10.5.  No way I would want to putt our surfaces much over that on a regular basis.  Playing time goes from right at 4 hours on a Saturday morning to 4 1/2 when the greens are pressed to 11.  

Higher mowing heights has also resulted in reduced watering and firmer greens.  

The original post was dead on.  Thatch and the issues around it can cause a cascading set of problems that takes diligence to undo.  And like any change on the golf course members have had to be educated at every step.

[Mike_Trenham]

TE Paul:

HVCC program sounds similar to ours but we top dress very little except when we are aerating, deep tying (sp?) or drilling and filling, however we roll 3 times a week weather permitting.   Our greens do dry out but we are pretty careful about stressing them durring the summer months with some of the diseases that are particularly hard on Poa.

It was reading about HVCC that changed my tune on this subject.  

[Don_Mahaffey]

 W.H.
I hope I didn't irritate you with my comments about thatch. You might be surprised by how many courses you could find with thatch levels at or in excess of 1 inch. I inherited a course that had some areas on the greens with thatch in excess of 2 inches! Skip a few aerifications, over water and over fertilize, don't topdress and groom often enough and it's not that hard to get behind the 8 ball when it comes to thatch. We know the problems caused by excess thatch, but getting golfers and decision makers to understand how important it is to do the cultural practices needed to keep it in check is the real job! Aerifying twice a year, combined with vertical mowing and topdressing can lead to some periods when the greens are less then perfect. Convincing everyone that those few periods are worth it because the majority of the season the greens will be great is the most important part of the whole deal. There are no short cuts to great greens.

[TEPaul]

"What members didn't understand was that the softness of the greens was scrubbing the speed off the ball."

W.H.

This is precisely what Dave Miller was looking for an answer on with this thread. To be honest I'd not much thought of what very thatchy greens (soft greens) could do to greenspeed given the same cutting height as firm, dry and non-thatchy greens. My super believes very thatchy greens at the same cut height as firm, dry and non-thatchy greens (let's just use 1/10th of an inch) can actually reduce the greenspeed by up to 10%!!  The example, therefore, if true, would logically translate to firm, dry and non-thatchy greens at 10 on the stimp rolling around 9 on thatchy greens. He wasn't all that sure why except thatchy greens must create up to 10% more friction or resistance to the roll of the ball. He also said that Penn State (where he went to agronomy school) is in the process of trying to determine exactly why that is right now.  

[TEPaul]

Don:

What you said in post #19 pretty much says all that needs to be known---there's just no getting around it although so many clubs don't understand that or just don't want to! They want and expect their greens to be perfect every single day basically and they just don't understand it just can't be that way when it comes to the necessary maintenance practices on putting greens, as you say!

[igrowgrass]

Why would you seed in bentgrass, if the poa has already shown that it is superior to the bent at your site?

[TEPaul]

"Why would you seed in bentgrass, if the poa has already shown that it is superior to the bent at your site?"

Clearly, one of the primary reasons to go to bentgrass (particularly the new A-1 and A-4 strains) in my basic area, the Northeast, is the worry and problems to putting greens connected to anthracnose outbreaks with poa annua. The other increasing feeback with bent grasses like A-1 and A-4 seem to be the real increased tolerance to stress of these new grass strains compared to poa. These new strains (A-! and A-4) seem to just love dryness!! At least that's been our recent experience at GMGC.

[igrowgrass]

Do you have a problem with thatch buildup or the annual bluegrass greens?  Seeding in bent to help combat anthracnose breakouts can be a good arguement.  But how many of those juvenile bent plants are going to survive the needed agressive aerification and/or verticutting needed to remove the excess thatch buildup?

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