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Tennis Court Renovations at The AELTC

by TurfCareBlog

In this Blog we hear from Will Brierley who is a Groundsman at Wimbledon tennis and he talks us through Tennis Court Renovations at The AELTC , which included koring work and steaming of the courts.

Not all that long ago I wrote about The Championships 2020 from the Groundstaff viewpoint. In that blog I mentioned two questions I was being asked a lot. In this blog I will aim to answer the second question frequently asked, “Are you going to rip up the courts this year?”

Question do you Need to Renovate ?

Its easy to think the courts have not had much play this year so is there a need for renovation at all? The simple answer to that is yes of course, quite how that looks compared to previous years probably needs some explanation.

​For that I’d like to go back to the early 2000’s, back then the courts while still around a 21% clay content – did not have the consistent ball bounce we have today.

The sward composition was perennial rye grass (PRG) and slender creeping red fescue, but now we are 100% perennial rye grass.

So why the change? Well through research carried out independently for the AELTC through the Sports Turf Research Institute (STRI) a ‘best grasses for tennis’ trial began and still continues to this day. Through the trial it was deemed that sward density could be achieved with a tufted grass (PRG) along with it being a more durable grass for wear, drought and shade tolerance. 

Koro was a Game Changers for Us

So how to go from the old grass mix to a single variety of grass? This led to the introduction of the Koro field top maker and what people think of us “ripping up the court”. This process enabled us to strip the plant material and a small amount of the rootzone. This will also help the removal of the seed bank build followed by tilling up the rootzone to make a new seed bed and then sow the new PRG seed mixture. 

Since that time we have been using the Koro regularly, initially to remove the thatch layer and existing seed bank and then to keep the levels of the invasive weed grass Annual Meadow Grass (Poa annua) at bay. The amount of Poa annua dropped from 29.4% to 0.1% in the first year of Koroing No. 1 court. Poa annua itself deserves a blog because it really is the biggest issue in keeping a clean and healthy playing surface for us. 

​So from around 2003 we started using the Koro annually in our renovation of the Championships courts, the machine evolved and our methods with it. Making sure moisture content is ideal is a critical part of this process because a 21% clay loam that has been dried out and played on all summer can become very hard.

Seed/Soil Contact key to Success

Tilled the koroed surface

Once a court is stripped off the rootzone is tilled (above image) to make a seed bed, seeded (we use a PRG 3 cultivar mix of Melbourne, Venice and Malibu), fertilised (using an 8-12-8+3MgO) and covered. After around a week – depending on weather conditions – we would have a good start to coverage of new grass. 

In around 2013 we realised that we were removing more loam than we were reintroducing and Koroing the courts every year was becoming unviable. We made the decision to start rotating courts being Koroed and move to a more traditional renovation of heavy scarification on other courts. This was working well at keeping the Poa annua content down and was also a time saver in autumn months for renovations where weather patterns can be a bit hit and miss. 

The Innovation of Steaming Courts

Steaming tunnels

In 2017 we introduced steam sterilisation, without a doubt the biggest renovation improvement in my time here. This process requires us to solid tine the courts beforehand as we would in any autumn renovation. Then a company comes on-site with a large boiler and pipework and run pipes to heat resistant poly tunnel sheeting.

The boiler is then turned on, the water is boiled and the steam is forced down the pipe work and into the sheeting. Once the poly tunnels reach their maximum expansion the steam is forced downward into the spiked holes.

The temperature of the steam starts at around 120°c from the boiler, but as it travels through the pipework to court it cools to roughly 90-100°c.

The tunnel is left in position for approximately four hours, this can be quicker or slower depending on moisture content in the profile and the weather conditions. Once the temperature is recorded at 70°c at a 50mm, depth then we are confident everything in that area has been killed off and the tunnels can then be moved to the next position.

We can run three tunnels at a time without losing too much pressure from the boiler and that will cover half a court. The logic behind this process comes from Holland and the flower houses, it is a clean sterilisation of everything living allowing for a change of variety of flower completely. It has also been trialled in football for nematode control.

End of The Poa Seed Bank

grass seed

Our aim was to control seed banks of Poa Annua that had built up in some courts (some being c100 years old), but we’ve seen added benefits of germination rates, winter colour, grass health, disease reduction and fairy ring control. We are unsure how long these will last and we will monitor year on year, but we are hopeful for at least five years, if not going on closer to 10. 

After steam sterilisation we then go back to stripping off the surface with the Koro and tilling up a seedbed as we did in previous years, as long as the weather is dry we can Koro the day after steaming. The risk is not having the weather on our side as once the plant is killed off it no longer wants to take up any water so prolonged rain can make the ground difficult to work on.

All courts not steamed in that year will then be renovated in the more traditional heavy scarification method. 

Renovations this year

​So, what are we doing this year? Well unfortunately due to Covid-19 restrictions it has not been possible to steam any of the courts. We decided that due to the type and amount of play this year, along with low Poa Annua percentages in the courts, we would be more than happy with a heavy scarification across much of the site.

The only Championships court we have used the Koro on is No. 2 Court as that was due to be steamed this year., we have also done a block of two practice courts. We have heavily scarified Championship courts 14 through to 18 and most of the practice courts, and we are looking to do Centre and No. 1 Court next. Championships courts 3 through 12 are still in use for another couple of weeks and then we will scarify those too.  

As with everything, we are always looking to improve our processes and find the best solution to create the best grass courts for The Championships, so I expect this to be an ever-evolving situation and I look forward to sharing more with you as we go on through the years.

Tennis Court Renovations at The AELTC by

Will Brierley

If you would like to see Will’s other blog on life as a groundsman at Wimbledon , check this blog out- https://turfcareblog.com/the-championships-2020-a-groundstaff-view-turfcareblog/

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