Grass tree pests and diseases

Page last updated: Tuesday, 10 June 2014 - 2:52pm

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The harvesting of grass trees for landscaping is popular as these striking specimens compliment both formal and informal gardens. This web article looks at the pests and diseases that affect grass trees.

The common grass tree (Xanthorrhoea preissii) is endemic to Western Australia and grows naturally in sand, loam or gravelly soils to a height of four metres. They have a lifespan of up to 600 years with a growth rate of only 1–2cm per year. Under The Environment Protection and Biodiversity Conservation Act 1999, it is an offence to take native vegetation including grass trees from public lands or state forests. Permits are required for commercial salvaging where the site has been approved for urban or industrial development. Land owners wishing to harvest grass trees from their property, must comply with state and commonwealth legislation.


The trunk is composed of a mass of old leaf bases held together by natural resin which can take ten years before it begins to form. The centre of the trunk is filled with a fibrous material. The needle-like foliage reduces moisture loss during periods of hot weather which makes the tree drought resistant. The root system is shallow with the main purpose being for anchorage. Surrounding the roots are microbes called mycorrhiza fungi which are essential for nutrient uptake in deficient soils and also protect roots against some pathogen fungi.