Poa Annua Eradication Success Stories - Are There Any?

[John Kirk]

I am not aware of a single instance of a golf course that has eradicated a significant colonization of Poa annua grass, once it has established a 5-10% presence in the turf.

As of 2011 or so, I know that Kinloch GC was able to keep a 1-2% poa population at bay by physically cutting it out.  Kinloch is a bent grass course in Virginia, in a very warm and humid climate.

My goal is to suggest that it is misguided to attempt to fight Poa colonization (in the cooler climates), and that initial grass selections should be made knowing that Poa transition will take place.

(Without any data, I am skeptical whether glyphosate (aka Roundup) resistant grasses are a good idea.  I predict a bad outcome.)

Any success stories out there?

[Jason Topp]

Hazeltine seems to be having success.  I know they gassed their fairways but are managing to allow bent to thrive and poa to die.  The super's blog provides good information on their efforts.


http://hazeltinenational.com/turfgrass_post/poa-in-fairways-summer-update/

[Randy Thompson]

We eliminated about a thirty to thirty five percent population over an eight to ten week period at Buenos Aires Golf somewhere around 2008-2009 but the Chemical wasn´t labeled for greens.

[Adrian_Stiff]

I think impossible in the UK to keep pure swards. Best we ever did was 99% for about 3 years, soon as we went to 2% invasion it became impossible to weed out, then each year it doubled thereafter. Pretty much every other story I have heard is that same sort of pattern. As far as I can tell you need days above 20C centigrade for Agrostis to really outwork Poa. The UK is probably only that sort of temperature for 10-15% of the time. Southern Spain/Portugal can do it.

[David_Tepper]

There was a thread here 6-12 months ago about controlling poa. I recall mention of a new weed killer designed to attack poa. 

[Justin VanLanduit]

It is a challenge but can be done with persistence and patience by golfing public.  The challenge is getting the facility to create an environment to allow the bentgrass to thrive; sunlight, air movement, and drainage.  The sunlight and air movement are usually the challenge as people don't want to see trees go.  Once an environment is established that promotes poa, best of luck to you.  We regrassed our greens in 2011 and so far are fairly clean but not 100%.  Chemical use is a key component in management, mainly PGR's (plant growth regulators) which inhibit the Poa's function allowing bentgrass to take over.  Some of the products recently brought to market to target Poa eradication have come back to bite people using them by severely damaging bent due to temperature and moisture fluctuations.  Lot of restriction in label of using.  Manual removal is key too; with changing cups 6 days a week I ask my cup changers to take a 10' perimeter from new cup and cut any out they see, can usually fix area like a ballmark then.


There is a new product that has been through trials and yet to be released that is looking promising.  The developer of the product is for the time being not interested in selling to the large companies as they want to have tight control over it and work with courses for application use.  I know guys that have done the ride through with them and they have said they will not sell product to them because there is too much shade.  Basically protecting themselves of killing the Poa but having a bad microenvironment for bentgrass to grow in and take over.


The newer bents do a good job of keeping poa out for the most part, whatever gets in is kept at bay.  You still manage the bent the way you would and that poa will somtimes die and sometimes survive but won't affect playability or asthetics.  Miss management will allow it to take over.

[Jon Wiggett]

Why eradicate it? A mixed sward is what you are going to get in most cases. You just need stop poa from taking over but it certainly is not a bad grass for golf courses.

[Ryan Coles]

Would I be correct in saying that newly invaded poa is worse to putt on?

What I mean by that is for example Wentworth were relayed and now are dreadful both in appearance and to putt on. Older greens with the same 50% poa seem a lot more refined.

[Ryan Coles]

What are the Grove (Hertfordshire) like these days?

[Jon Wiggett]

Would I be correct in saying that newly invaded poa is worse to putt on?

What I mean by that is for example Wentworth were relayed and now are dreadful both in appearance and to putt on. Older greens with the same 50% poa seem a lot more refined.

In my experience when it first appears it tends to be in blotchy patches of a monoculture fashion. However over a period of time with conducive maintenance fescue and bent recolonize the patches leading to a more even mix of grasses. However, as poa is such an adaptable grass I also suspect that the poa alters due to the climate it is in.

Jon

[BHoover]

Pure sward is the best sward.

[David_Tepper]

There is a link to a 35-slide power point presentation (in pdf format) on controlling poa here:

http://r.search.yahoo.com/_ylt=AwrTcc1Hh_hVtsMATHEnnIlQ;_ylu=X3oDMTByYnR1Zmd1BGNvbG8DZ3ExBHBvcwMyBHZ0aWQDBHNlYwNzcg--/RV=2/RE=1442379720/RO=10/RU=http%3a%2f%2fwww.nysta.org%2fturfshow2013%2fAskew_PoaCure.pdf/RK=0/RS=SkOBljsAiU3guYKjFXLkLZVEOUs-


Info on Methiozolin here:

http://www.moghu.com/eng/02_product/01_product.php
 

[Adrian_Stiff]

Pure sward is the best sward.

You are correct, however location plays a massive role and in some places you can't keep pure swards at putting green heights.
I don't know what the construction method or seed mixture was at Wentworth, assuming it was USGA mix and a very strong European bent grass mix there comes a point the invasion (at 2% poa I'd say) it is very difficult to hand weed out as it has usually rosetted at that point so you need to plug.
My UK advice is; A: live with a poa mix or  B: move your golf course South

[BHoover]

My course has mostly pure bentgrass greens and fairways (to my untrained eye). Unlike many other courses in the area, the greens are not covered for the winter. The cold temps kill any poa that does infest the sward and because of the lack of non-bent in said sward, the result appears to be pure sward.

[Jon Wiggett]

Pure sward is the best sward.

Brian,

WHY is that the case??? and what do you perceive as being the drawbacks if any in a pure sward?

Jon

[Mark Bourgeois]

Eventually doesn't poa go from an annual to a perennial with the "proper" climate and with management oriented towards this outcome?

When we talk about poa on the greens of GB&I links, is this what we mean?

And if anyone has the patience to answer more stupid questions: from the perspective of the golfer what's the difference (advantages) between perennial and annual poas?

Nevermind if there is no such thing as poa perennial. Chalk it up to my new hobby of making cocktails using formaldehyde.

[John Kirk]

Thanks for the responses so far.

Poa pratensis is "Kentucky bluegrass", a perennial species of the Poa plant.  It can be found on many golf courses, especially used as a hearty variety of rough.

A discussion of Poa annua evolution, from a stalky annual plant to a smooth, leafy perennial plant is presented in "Developing annual bluegrass cultivars for putting greens", by David R. Huff.  The plant evolves and adapts to a low mowing environment over a period of 30-50 years.  The USGA article is found here:

http://www2.gcsaa.org/gcm/2006/dec/pdfs/073-088_dec06.pdf

Here in the northwest U.S. (west of the Cascade Mountains), there are no examples of courses which have successfully repelled Poa annua colonization.  And once it establish a foothold, it quickly takes over.  My home course, Pumpkin Ridge GC, saw the following progression:

Year 7 or 8:  Poa is easily visible in greens, perhaps 1-2% of grass.  Club physically cuts all Poa plants from greens.

One year later:  Poa now comprises 4-6% of grasses in greens.  Club gives up practice of physically removing, and begins process of encouraging Poa to colonize further.

The next 4-6 years:  Greens were bumpy and inconsistent.  Greens are rarely maintained at a Stimpmeter speed above 10.5 feet, though it was possible to host successful USGA events (Women's Open, Junior Amateur, etc.) when required.  Some greens are better than others; Ghost Creek #4 green in in a shady hollow, and transitioned to Poa years before the others.  Some were very florid with poa flowers in spring and summer, to the point of appearing yellowish at times (Ghost Creek #13, Witch Hollow #8).  By the end of this six year period, greens were 75-100% Poa.


Ten years later:  Greens are 99-100% Poa annua, much of it with small blades and very tight turf.  During cooler weeks in summer and fall, greens can be rolled 2-3 times per week to yield fast greens conditions (11-12 feet).

Fairways are 90-95% Poa (originally bentgrass).  Roughs are 70-80% Poa, plus some ryegrass (mostly because some rough areas were resodded) and perhaps 1-2% creeping bentgrass.  Bentgrass rough is too difficult, and undesirable.

Overall, the course plays pretty fast in the summertime.  A low hook with overspin will roll a long way.  Grass browns out a bit in July and August, and some Poa rough seems to die off and go into a dormant state.


That's what I see.

[Mark Bourgeois]

30-50 years to go perennial!

Okay, Plan B: we start heating up the atmosphere, creating poa-killing temps especially in the Pac NW.

Too expensive?

[John Kirk]

Hi Mark,

You will note that our greens, after a mere 25 years, have a significant percentage of the good stuff already.

[BHoover]

Pure sward is the best sward.

Brian,

WHY is that the case??? and what do you perceive as being the drawbacks if any in a pure sward?

Jon

Relax, I just like using the word "sward" as much as possible.

[Jon Wiggett]

Pure sward is the best sward.

Brian,

WHY is that the case??? and what do you perceive as being the drawbacks if any in a pure sward?

Jon

Relax, I just like using the word "sward" as much as possible.

 

[Wayne_Kozun]

Why eradicate it? A mixed sward is what you are going to get in most cases. You just need stop poa from taking over but it certainly is not a bad grass for golf courses.

one reason to eradicate it is if you are susceptible to ice covering the greens for over a month. Many clubs here in Toronto had that problem in the winter of 2013-4. Greens with a significant amount of poa were in horrible shape until August

[Jon Wiggett]

Wayne,

yes it is susceptible to ice damage but also recovers quickly. As long as it is kept down to a reasonable % of the sward this should not be a problem though especially if you ensure the grass is fully dormant before the winter comes.

Jon

[Steve Okula]

John Kirk said about his home club Pumpkin Ridge, ,

"Greens are rarely maintained at a Stimpmeter speed above 10.5 feet,"

I interpret the tone to indicate that green speeds of 10.5 feet are considered inferior, at least at Pumpkin Ridge.

What speed would be satisfactory?

[Jon Wiggett]

Steve,

I guess that will alter from course to course and probably also player to player.

Jon