Update on Transition Trial

Bahia grass (Paspalum notatum) tends to invade turfed areas in large parts of eastern Australia, replacing the more desirable grass species usually present in these environments. This not only reduces the quality of the turf, but leads to higher management costs through increased mowing requirements.

To explore the best ways to transition this species out of turfed areas, the Integrated Vegetation Management Project (IVMP) is conducting a 12 week trial. Throughout this trial, low rates of various herbicides are being applied monthly to duplicated trial plots. Changes in the species composition of the plots are being measured over time, with untreated plots also set up for comparison.

Figure 1: The treated area on the left has a substantial cover of blue couch, while the untreated area directly adjacent to it is dominated by Bahia grass with numerous tall seed-heads.

Two months after the commencement of the experiment, several of the treatments have significantly reduced the cover of Bahia grass in the plots while allowing the cover of more desirable species to increase. Figure 1 shows a plot that had some initial cover of the desirable grass species blue couch (Digitaria didactyla). Two months after the start of the trial most of the Bahia grass has been removed from the plot, and it has been replaced by the desirable turf species.

However, if a plot had very little or no desirable turf species initially present, the bare areas created by the removal of Bahia grass have been invaded by undesirable species. These situations clearly demonstrate that transitioning Bahia grass out of turfed areas should only be attempted where there is some cover of desirable turf species.

Figure 2: Part of a treated plot with most of the Bahia grass removed from it. Only a small amount of blue couch is present, with most of the area now bare or invaded by crowsfoot. 1 = blue couch; 2 = dead or severely damaged bahia grass; 3 = resproutnig Bahia grass; 4 = crowsfoot

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