St Andrews Links Blog

Pearlwort – the precious weed

Managing fine turf is a constant battle with nature. From poor weather to fungal diseases, weeds, disorders and compaction – we face these challenges head on to try and produce the best surfaces possible.

One such challenge, particularly prevalent to links turf, is the perennial weed; pearlwort (sagina procumbens).

We find this weed all over the golf course, but is most problematic when established on a putting surface. Looking at the picture you may ask why? It certainly looks like an area of very dense, green grass so what’s the problem?

Firstly, at certain periods of the year it can produce tiny, white, pearl-shaped flowers (hence the ‘precious weed’ nickname) at which time the colour of the weed will change. This results visually in a very uneven greens surface. The firmness of the green is also affected due to the patch of pearlwort being softer than the fine turf. If left uncontrolled, it can quickly establish into large patches.

Control of this weed is tricky. It tolerates close mowing and can handle vertical mowing and scarification. One method is to keep the turf vigorously growing with increased nutrient applications. This allows the turf to out-compete the weed. We can’t overfeed, however, as this would result in slower greens with higher organic matter and the long term ingress of the weed grass; poa annua.

Chemical control is possible with a selective herbicide containing the chemicals dicamba, mecoprop-p and MCPA. When applied, this product slowly kills the weed plant and leaves the fine turf untouched apart from a slight loss of colour.

Pearlwort dying off after herbicide application

As the weed slowly dies, grass will recolonise the patches. This process can be helped along by first vertically mowing the area. This rips out the dying weed leaves and creates space for the new grass to grow. This can then be followed by an overseed with fine grass species such as festuca or agrostis (fescue or bent) and finally a light feed with a liquid fertiliser.

Greens on the Eden, Strathtyrum, New and Jubilee Courses have all recently been sprayed with the herbicide with works planned for the Old Course during this month.

Words by Graeme Taylor, Course Manager – New & Jubilee Courses

 

Header image credit: (lawnweeds.co.uk)