Our Course Superintendent, Mitch Hayes will be presenting articles on a regular basis explaining aspects of our golf course operations and procedures. His first item (below) explains why our Zoysia collars are necessary. If there is a topic on which you would like Mitch to provide his thoughts, please let us know so we can present your suggestion as a potential future article.
The Role of our Zoysia Collars
On golf courses all around the world that grow multiple turf species over multiple playing surfaces – on tees, fairways or rough – encroachment has been an ongoing battle for Committees and Course Superintendents.
This approach to course composition has been led by demand for faster putting greens, and the response from the turf industry was to introduce new, smaller species with denser canopies, which allows for a better rolling surface for putting. But when these additional species are introduced, encroachment becomes inevitable because fairway grasses have a more dominant growth habit because of their larger root and shoot system.
Additionally, due to fairway grass being cut higher, this places less stress on the turf, enabling it to photosynthesize more efficiently resulting in a healthier plant which simply ‘bullies,’ its way into the green. Once that grass is in the green it is very difficult to control as it grows faster than it can be removed, resulting in the gradual shrinking of the greens area.
This was the case here at The Brisbane Golf Club when I arrived eight years ago, as some greens had experienced significant encroachment of up to three meters and was one of the major catalysts that led to the conversion of our greens from Tifgreen or 328 to Champion Bermudain 2012. The solution to this encroachment was to introduce a perimeter of Zoysia grass – called a ‘collar’ – around the greens to prevent the fairway grass encroaching into the greens. In our case it was Nullarbor Couch that was moving into the Champion Bermuda. We acted on the theory that the Zoysia is very slow growing, with little lateral growth, so the risk of it encroaching into the Champion grass on the greens was very low.
Additionally, the grass would act like a buffer in which the fairway grass could be selectively killed with herbicide before reaching the green. This was trialled on the early greens but, for several reasons (listed below), was not successful.
- The pesticides used to control the fairway grass are unregistered and require a permit to be obtained for a trial basis. Permits are only available short term and not sustainable for ongoing management
- We found that the pesticide used caused phototoxicity in the Zoysia grass, causing it to wilt and stunt its growth. Lower rates were also trialled in response to this but had limited efficacy in controlling the fairway couch
- Spraying couch encroachment into the Zoysia collar left dead/bare areas as the Zoysia is extremely slow growing, resulting in the fairway grass growing back into the same areas, rendering the work superfluous
- The unsuccessful herbicide trial meant course staff had to continually patch or replace areas of the collars as we were losing the 400mm collar to encroachment during the growing season
Eventually the herbicide approach was abandoned and additional strips of Zoysia turf were laid to slow the time it took the encroachment to reach the green. We eventually found a balance point of 1.2 meters of Zoysia (three strips) allowing us to have a programmed replacement collar schedule, known as the ‘strip-and-replace’ method.
Although the strip-and-replace method is quite rudimentary, it is effective in controlling encroachment as the contaminated collar is killed and removed, and replaced with a fresh one.
In the early days a cultivar called Shadetuff was used, as it is the main fine-leaf Zoysia breed available. However, an inability to handle wear and tear meant that we would lose areas of grass in high-traffic areas during the winter months.
In 2017 we trialled a new Zoysia called Sir Grange (known as Zeon in other parts of the world). A complete Sir Grange collar was first installed on the 12th green in December 2018 and we found this cultivar competed better against the surrounding couch, and it had a higher threshold to wear. Now, as a result, Sir Grange now constitutes around the 90% of our green collars. These collars are edged monthly to slow Couch encroachment, but eventually it will adapt and the roots will dive below the edger blade and pop up in the collar.
When members ask if the Zoysia collars have been successful, I always reference the original objective – to prevent our greens from becoming smaller via fairway grass encroachment. Over the years that we have been using this process we have not lost any area from encroachment, but that’s not to say we haven’t had any encroachment from Couch. We have, but it’s been very minimal as we are able to poison those areas, replace the Champion and Zoysia to successfully maintain the size of the green. And to say we have not lost any area of our greens after almost a decade from inception of the Zoysia collar would suggest they have been quite successful.
I understand that use of this grass is controversial as it changes the dynamic of the golf course. But any new grass introduced to the course would add another element, and brings its own complexities. For example, I have seen some clubs use the same turf species as the green. This presents challenges in winter for players when balls are putted off the greens as they offer little help as a back stop because the grass hardens when dormant. The beauty of using Zoysia is that it has a naturally dense canopy and visually defines the perimter of the green. In addition, it is extremely slow growing and has very little lateral growth, so the risk of the grass entering the green is extremely low.
Over the years there have been many different methods and studies trialled all over the world to combat encroachment without success. I am constantly looking for new methods to overcome our encroachment issues and will continue to trial new grasses/methods to balance course playability and agronomy. Currently our method is the most popular, and it is encouraging to know that many clubs in Queensland are following our lead.
Mitch Hayes, Couse Superintendent