Friday, November 12, 2010

Encroachment 3

Encroachment is a dirty word when it comes to golf greens and unless you have a large pool of resources at your disposal it is very hard to combat.  I am talking about foreign grasses invading the putting surface and pretty much the best way to successfully prevent it is constant monitoring and hand removal, which is very labour intensive.  Selective chemical controls are limited in Bentgrass greens and non-existent in Couch greens. 

There have been several barrier type products promoted over the years as a successful method but I am yet to see them be successful over the long term.  Other methods include running an edger blade around the perimeter which, whilst partially successful, also requires a large labour input and you finish up with a small groove that relief needs to be taken from and the line of play can be interfered with.  Painting Roundup on with a paint brush has been tried but you cant have players walk on it or else they will spread the chemical so on a course as busy as ours this is also not viable.

A couple of months ago we sprayed out some collars and areas on the River greens as reported in Blog posts on September 7 and 14.  The old turf was only removed to sod cutter depth following application of a herbicide and the concern with this is regrowth of the Couchgrass.  In the photo below you can see Couch re-shooting after 300mm of soil was removed at the nursery green, so I don't hold out a lot of hope on the River greens despite the application of herbicide.

Regrowth of Couch after 300mm of sand removed
The West greens have a similar problem with Couchgrass constantly encroaching.  There is a product registered for the control of Couchgrass in Bent greens but it is not effective on all types of Couch.  It is interesting with this product that in the USA the label warns not to apply it to putting greens!  I have used it since I arrived here and had good success against the susceptible varieties early on but now really only apply it to limit the invasion.  Over the past 3 summers I have been trialling a new product with some success although the downside is that there is some dis-colouration of the Bentgrass.  Trials are continuing this year and you will notice this dis-colouring over the next few weeks. As I don't believe it interferes with the putting surface I am happy to continue the trialling and hope we have the same success as  last season..

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