Seed-Head Supression Trials at 9 Weeks

The Integrated Vegetation Management Project (IVMP) trial that is investigating the suppression of Bahia grass (Paspalum notatum) seed-head production is now nearing its conclusion. At the beginning of this trial various herbicides and plant growth regulators were applied to duplicated trial plots, with their effects on seed-head production being monitored over time.

Following recent heavy rainfall, the areas surrounding the trial plots and the control plots are now full of numerous Bahia grass seed-heads 70-80 cm tall. The latest assessment of the trial plots was undertaken 9 weeks after the commencement of the experiment.

At this time most of the treated plots were still showing >80% reduction in the number of seed-heads produced, with the five best treatments having >98% reduction in seed-heads (See Figure 1). However, the two poorest-performing treatments are no longer much better than the untreated control plots.

Figure 1. Seed-head Production of Bahia grass (Paspalum notatum)

Overall, most of the treatments are still performing surprisingly well, considering the amount of time that has elapsed (i.e. 9 weeks) and the amount of rainfall since the commencement of the experiment (i.e. approx. 450mm rainfall since January 1st). 

This image shows part of a treated plot 9 weeks after spraying. There are no Bahia grass seed-heads in the treated plot, while the untreated area in the background has a dense stand of 80cm tall seed-heads.

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