Serrated tussock on "Yellangalo"
Written by Fiona Leech, District Agronomist, NSW Department of Primary Industries.
Michael and Alison Nicholls came to Yellangalo from Sydney in 1989. Yellangalo was well and truly infested with serrated tussock and it was very evident elsewhere in the area. They knew before buying the property there was a major weed issue and were prepared to tackle it. The Nicholls sought professional advice by approaching NSW DPI to help develop a plan of attack.
From around 1978 the management of serrated tussock has been enhanced by the use of flupropanate herbicide. Unfortunately in 1998 flupropanate (Frenock®) was withdrawn from sale for commercial reasons, creating a large gap in control options. NSW DPI evaluated the efficacy of glyphosate and how best to use this herbicide for serrated tussock management. Alison and Michael agreed for NSW DPI to carry out some of the herbicide trials on Yellangalo. The research showed that glyphosate can be an effective tool for managing serrated tussock and as a result of these trials and others on the Monaro several glyphosate products were registered for serrated tussock control. Flupropanate was returned to the market in 2000.
Despite the fact that you could not buy flupropanate in the late 1990’s, the Nicholls had a quantity of Frenock® on hand which they continued to use it in a strategic manner. During the 1990’s they had done extensive broadacre spraying to help reduce the serrated tussock load. They also owned a rotowiper which proved a useful way of selectively removing serrated tussock from their native based pastures. NSW DPI convinced them that the best way to have the edge on serrated tussock in the longer term was to work towards sowing down introduced pastures across the arable areas of the property.
The process involved spraying out paddocks in the spring in preparation for crop the following autumn. The Nicholls often cropped paddocks with triticale for 1 - 2 years before sowing them down to phalaris/cocksfoot/fescue/subclover pastures. The presence of introduced grass species allowed the use of low rates of flupropanate to selectively remove any newly emerging serrated tussock seedlings.
Due to the high cost of pasture renovation and the fact that paddocks are out of production for up to 12 months it was only possible to make changes slowly. However the Nicholls were committed to trying to turn Yellangalo around.
There are still paddocks on Yellangalo which are less arable and contain some native pasture species. These areas have proven more difficult to manage because the herbicides registered for use can be very damaging to native pasture species. Whenever considering the spraying of a non-arable paddock badly infested with serrated tussock it is important to look for desirable background species as these that will help outcompete the tussock. Wherever feasible, choose a spray strategy that will do as little damage as possible to the background species.
The key message is that spot spraying is really our most selective tool available so it is critical that paddocks containing scattered serrated tussock are never allowed to reach the stage of a dense infestation. Once paddocks, particularly non arable areas containing native pastures become dominated by serrated tussock, there are no straightforward, low cost solutions available.