Saltene and Couch Grass

I thought I would talk about this subject instead of what has been run of the mill course work updates lately, nothing like a bit of variety to keep it fresh...

It is this time of year (summer if you didn't know better) the couch and saltene in the greens become more visible and start to out compete the bent grass. If you have been good students and followed the turf 101's on this blog you would know Bent is a cool season grass preferring cooler temps, Couch and Saltene both warm season grasses preferring hotter temps for optimum growth.

So what happens when the two compete against each other year round ?
 
During the cooler months,  April through October the Bent grass out competes the Couch and Saltene, the Couch and Saltene are still there just not as pronounced as during the warmer months, thanks to their vigorous rhizomes even tho the bent has control of the top, the couch and saltene are waiting to pounce when warmer temps arrive due to their extensive rhizome systems.
On the other side during those warmer months, November through March the Couch and Saltene have the advantage and out compete the Bent difference being if allowed to go unchecked the couch and saltene would eventually in a rather short period of time completely take over any given area that offers it good growing conditions and crowd out the weaker bent grass.
Lighter colour is Couch
To be straight the only TRUE means of controlling these grasses in Bent grass greens is by physical removal, IE removing the turf and soil profile to at least 150 to 200mm and replacing with uncontaminated material.
At present this option is not viable for us as we do not have a bent nursery at present to resurface greens, eventually our plans are to construct a bent grass nursery primarily for this purpose but is dependent on the back 9 irrigation system upgrade going ahead.

We are not talking about just encroachment from the green perimeters which is the usual problem many courses face, some greens have been extended over many years and now contaminated material is well inside the perimeters of the green.
That said, we do not just let it go, if we did you would be putting on 90% couch grass greens through summer, we do intervene by chemical means to suppress the couch and saltene, options are limited without damaging the bent grass, it is expensive and does take time to make an indent into the colonised areas of Couch and Saltene which have occurred over a very lengthy period of time.

We have a program in place to suppress further encroachment and eventually turn back the tide slowly, using selective herbicides applied at optimum times along with growth regulators and cultural methods but as I said it is a very slow process without resurfacing to reverse the encroachment, when we finally get the go ahead for the irrigation upgrade we will implement a resurfacing program to remove the couch from the worst effected greens.
A smaller nursery area is being considered to use for the 5th which seems to be the worst effected after a green extension some years ago.

I hope this 101 helps you understand the coming couch grass problem in the greens and the long term measures to address it.

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