Horsetail: declared pest

Page last updated: Monday, 20 July 2020 - 3:07pm

Please note: This content may be out of date and is currently under review.

Horsetail, common horsetailbottlebrush, field horsetail, horse pipes, mare's tail, snake grass, shave grass, scouring rush (all Equisetum species including Equisetum arvense) are declared pests in Western Australia (WA). This article describes the nature of the plant with links to requirements land owners/occupiers must adhere to, pest control methods and how to search, detect and report it.

Form: herbaceous — perennial

Status: present in WA


An erect, non-flowering perennial herb native of Europe, Asia and North America. It has ribbed or grooved annual stems 10-60cm high, and tuber-bearing creeping rhizomes (underground stems). Spreads primarily by rhizomes and root pieces, but also reproduces by spores.

Sometimes cultivated and extremely difficult to eradicate, especially in rocky soils. Grows mainly in damp places. Outbreaks have been controlled following spread from plantings in New South Wales, Victoria, Tasmania and Western Australia. Plants have high silica content and have been used for scouring pots, hence the common name, scouring rush.

Stems: annual, stems can be erect or lay flat on the ground with only the tips being erect. They are jointed and two types are formed. Vegetative stems are green, growing to greater than 50cm high, 1.5-5mm diameter, hollow, with whorls of solid three to four angled branches rising below the cup nodal sheaths.

Fertile stems are whitish, appearing in early spring, growing to greater than 30cm tall and up to eight millimetres in diameter, succulent, unbranched, jointed with sheaths (14-20mm long) around each node, terminating in a long-stalked spore-producing cone. Fertile stems often lack the side branches.

Leaves: reduced to a papery crown of six to 18 scales at each stem joint. Green on the main stem, but often dark brown on lower stem.

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Agricultural and economic impact

Horsetails are highly invasive, difficult to control and toxic to livestock. They can be allelopathic.

Declared pest category

The Western Australian Organism List (WAOL) contains information on the area(s) in which this pest is declared and the control and keeping categories to which it has been assigned in Western Australia (WA). Search for horsetails in the WAOL using the scientific name Equisetum. Each Equisetum species in WAOL has a declaration and declaration map.

Requirements for land owners/occupiers and other persons

Requirements for land owners/occupiers and other persons if this pest is found can be sourced through the declared plant requirements link.

Search > detect > report

MyPestGuide™ Reporter
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Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080


Detectability: medium difficulty to find. Horsetails are primitive plants without flowers or obvious leaves. Horsetails have two types of stem. The sterile stems are hollow and jointed, and some resemble giant sheoak shoots. The fertile stems produce spore-bearing cones at their tip.

Who is likely to find it: the nursery industry, fern enthusiasts, herb growers, permaculturists, home gardeners, landscapers and other horticulture professionals.

When to find it: this is a perennial plant so it could potentially be found at any time of year.

Where to find it: it is likely to be found in cultivation in pots or in the ground. Three previous documented infestations in WA all resulted from cultivated plants.

Control method

Control methods for this declared plant can be found through the horsetail control link.

Management calendarTable displays: Search Jan-Dec. Dormant May-Aug. Germination: of spores Dec-Feb. Actively growing: sterile stems Sep-Apr. Actively growing: fruiting stems Sep-Oct. Fruiting: spore production Dec-Feb. Treatment May-Aug.

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080
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