Message Board - Natural Turf: How I killed my grass tennis court - Confessions of an idiot!!!!!
1 Sep 2010 by philipfish
Hi all,
Last week I decided to apply a weak Glyphosate solution to my tennis court in order to kill the Poa ahead of rennovations (see http://www.pitchcare.com/message/message/20075). I used my 4 nozzle walk-behind sprayer (Evenspray 300) with 110 degree flat nozzles. I had been advised to use a rate of 100ml/Hec which I tested on a small area with good results (this season Poa killed fine grasses OK). I was warned not to overlap each pass otherwise I would be applying too high a concentration and it may kill some of the finer grasses. To avoid overlap problems I used spray marker.
The result is shown in the photo.
My first thought was that I had accidently overlapped too much. But I had been very carefull. However, on examaning the boom on my sprayer I realised that it was not set perfectly horizontal (the boom dipped 1.6 degrees with a 4cm height differance between the extreme nozzles).
Having now drawn-up the configuration on graph paper using my sons protractor I realise that I had inadvertently created two bands (one of 20cm and one 17cm) where I was getting overlap from three nozzles (instead of two), resulting in appling arround 50% too much Roundup. Hence the strips of dying grass in the photo!.
Being a little out has never been a problem when spraying for weeds, applying iron or liquid fertilizers but is critical when doing something where the application must be exact.
WHAT AN IDIOT! TAKE ME OUT AND SHOOT ME!
MAKE SURE YOUR EQUIPMENT IS SET UP CORRECTLY.
Phil
1 Sep 2010 by Sumomosr
Are you any relation to Michael 
GOGGA
1 Sep 2010 by Greenfingers
Chin up Phil, we all make mistakes from time to time.
1 Sep 2010 by Mike
I have an Evensprey, and the way the boom is mounted is my only complaint with it... I think the design is crap! Ensure that you measure the height of the boom at both ends before proceeding with any spraying.
Mike
1 Sep 2010 by tonybolton
Thanks for the hurricane warning Sumo
A Freudian slip is when you say one thing but mean your mother
2 Sep 2010 by Mark Frever
Phil,
This is a different approach for killing Poa for me. How aggressive is your renovation? I think of complete kill when using Glyphosate.
I consult with a homeowner on Poa annua/Kentucky Bluegrass/Perennial Ryegrass tennis court in lower Michigan. Weather pattern is similar to Denmark.
We are letting the Poa survive because the homeowner appreciates the density of the plants. I have turned the cultural practices in favor of the Poa.
Can a tennis court survive with Poa as the dominate grass?
Mark
2 Sep 2010 by jlawrence
I thought the amount to use was less than 100ml/Ha. more like 5ml/Ha or was that 5ml of active ingredient - I'd need to check my notes. I think when doing something like this it is better to leave a gap between runs and risk missing bits rather than have something happen like killing lines.
Of course there's no bounce, bend your back and put some bloody effort in.
2 Sep 2010 by petermarkcraig Last edited 2 Sep 2010
A salutary lesson Phillip and respect for illustrating your mistake to help others avoid it.
Reminds me of my early days at Leyland Cricket Club in 1979 when I decided I wanted to eradicate the clover from the cricket outfield using Clovotox.
Having left school without learning the metric system properly, I had to convert the metric application rates on the label to imperial. Once done I spent the entire morning spot treating clover with what must have been a dozen full knapsacks.
I thought the smell was a little pungent but I carried on regardless. I finished spraying around lunchtime, and by late afternoon the clover was already turning its toes up.
This did worry me so I checked the label which said the clover should show signs of deterioration after 3 days and not 3 hours!!
Panic set in and I rechecked my calibrations to discover that due to a misplaced decimal point I had mixed the clovotox at 10 parts chemical to 1 part water instead of 100 parts chemical 
By the time of the president's Day which was why I wanted to clear the clover the entire outfield had dozens of white/brown patches all over it.
Fact is if they had sacked me on the spot I'd have walked no argument. But they didn't and needless to say I have never made a mistake with chemical calibration since and neither have any of my teams.
Of course the grass looks good. The sun is shining.
2 Sep 2010 by philipfish
JL
Checked the original advice. "The application rates are 100ml of Glyphosate to 100 litres of water per hectare". I used 8ml Glyphosate in 35ltr over 800 sq m.
Mike A
Agree entirely. Evenspray 300 is a good machine but its so easy to knock the boom off the horizontal!!! Lesson - check boom each time.
Mark Frever
I have accidentally encouraged the Poa thru over watering and overfeeding. I shall scarify hard during renovations to remove as much as possible. The best way to remove is thru drought, which kills the Poa. May also use ethofumesate during renovations (if my grass recovers). I am also starting to aerate a lot more.
Phil
2 Sep 2010 by willard
Spraying out poa from cool season grasses like rye is very tricky. I wouldn't do it.
If you were dealing with warm season grasses, you have a little more room for error.
Many groundsman have used roundup to spray out poa or rye from couch, simply because it is cheaper than the advised products.
Not encouraging poa to flourish is your best method. Starve it out during the hot season.
Reducing fert & water helps, you appear to already have grasped this.
Go hard on your renovs. Good luck!
2 Sep 2010 by vid
Phillip I'm very definitely with PMC above - great respect for you coming on here and admitting to the mistake and equally great respect for going ahead when there was a lot of caution being advised.
I cant see that a small angle to the boom would make that much difference but the setting of the nozzles if not precisely fixed would make a huge difference as would the absolute precise setting of the height of the boom and the presence of any wind. I would have tried half rate first to avoid overlaps but this application is off label and therefore dubious in its accuracy.
Very brave Phillip and so sorry to see the results - good luck with the renovations
4 Sep 2010 by Steve63
Is this method of applying glyphosate legal?
I have not been able to find this selective control of Poa annua on the product label,
http://www.rigbytaylor.com/Search/0488276-05.htm
Don't talk to me about Contractors Wonka, I am one myself......
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