Chilean Needle Grass - Is there an oil for that?
Chilean needle grass (CNG) represents a significant financial burden to landholders and managers of public land. The identification of an alternative chemical with herbicidal activity similar to the currently registered synthetic chemicals would increase the tools available to producers for long-term management of CNG.
Essential oils are natural oils obtained by distillation. They comprise a complex mix of volatile low-molecular weight compounds such as isoprenoids, monoterpenes and sequisterpenes and some exhibit herbicidal activity which has been shown to have a residual effect on a number of weed species. An example is pine oil which has been used with some success to control branched broomrape seed banks in South Australia and to reduce germination of serrated tussock and cane needle grass (same genus as CNG) in pot experiments. Anecdotal reports claim that the use of essential oils can reduce spray regimes by up to 50%. However, there are few reports of the impact of essential oils on more desirable pasture species in a mixed pasture.
The use of essential oils could potentially reduce costs associated with chemical control of CNG by 50%. Based on current distribution this could be a saving of $180m per year (roughly $45 per ha pa). When incorporated into an integrated management package the use of an essential oil product would decrease production losses through competitive pastures and less injury to stock and degrading of product. The use of an essential oil product to control CNG would also decrease the use of synthetic chemicals such as Glyphosate, which has garnered negative attention from the wider community around human health and environmental concerns.
The principal aim of this new study is to determine if essential oil products kill mature CNG plants and/or reduce germination of CNG panicle and cleistogene seed, but also to determine if there is a negative impact on other pasture species that CNG will be competing with. If essential oils do impact the viability of CNG plants and seed a scoping study will be required to determine how these products could be used on-farm and to determine the practicability and the economics of using essential oils as part of an integrated CNG management package.