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PPS Annual Grass Control Project

Updated: Oct 12, 2022

Three year farm demonstration exploring a broad range of management techniques for controlling annual weeds in pastures.

The incursion of annual weeds into pastures and a reduced number of herbicide options for their control has prompted PPS to look for a broader range of management techniques on which this three year on farm demonstration is focused.

Barley grass (predominately), brome and silver grasses continue to be an issue in pastures, especially after periods of dry conditions and perennial pasture thinning. These annual grasses have huge impact on the ability of growers to turn off seed free meat and wool, thus incurring price downgrades to various extents, in addition to the price downgrades there are significant animal health issues that arise from the sharp seeds. The invasion of annual grasses also has a deleterious effect on desirable pastures; competing for light, nutrients and moisture.

Current control methods are mostly herbicide based with some mechanical techniques also carried out in the form of slashing or hay making. Current practices are not reducing the problem sufficiently to minimize the impact of the invasive weeds. Barley grass has benefited from the increase in soil fertility associated with pasture improvement and has become an increasing problem since the dry years of 2014 – 15.

PPS is testing for herbicide resistance on selected member farms to gauge if resistance is an emerging problem locally, initial results are available in this report.

PPS members are currently exploring alternative methods of annual weed control which are outlined below:

- Pasture competition – Over sowing productive species into older perennial pastures to reduce the opportunity for annual grasses to invade the pasture.

- Dry sowing of clover – Sowing clovers in late summer to have them emerge at the autumn break to increase early competition.

- Spray topping – Employing optimal timing of spray topping practices and investigation into alternative chemical options.

- Seed removal options – Hay, silage or mechanical topping. The use of silage has been shown to be effective in the region but has not been widely adopted by producers. A successful demonstration could change this.

- Grazing management – Using sheep or cattle to harvest bulk feed early in the season, with the aim to reduce seed set over several seasons.

PPS aims to demonstrate single or combined methods of reducing annual grass weeds in perennial pasture on member farms.



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