Horsetail

(Equisetum species)
Horsetail potted plant, image: K. Bunn

What is horsetail?

Horsetail is a pasture and crop weed and can also invade native vegetation.
Horsetail is a declared weed in Tasmania under the Tasmanian Biosecurity Act 2019 and associated Regulations. The importation, sale and distribution of horsetail are prohibited in Tasmania.

How to identify horsetail

Horsetails are very ancient, non-flowering perennial (long-lived) herbs growing to 60 cm high.
There are two types of stem. The fertile stems appear in early spring, are whitish in colour, rather succulent, unbranched, growing to about 30 cm tall and 8 mm in diameter and terminating in a spore-producing cone. The sterile stems grow to about 50 cm tall and up to 5 mm diameter. They are branched, hollow and grooved, green in colour and with whorls of 6 to 18 leaves. The sterile stems first appear in late spring after the fertile stems.
Horsetail has tuber-bearing, hairy rhizomes (underground stems) which in a large infestation can form a layered mass up to 30 metres across and 5 metres deep.
Horsetail stems die back to the rhizomes each winter and regenerate the following spring.
If you suspect you have seen this plant it is important to report it to Biosecurity Tasmania on 03 6165 3777 for confirmation.

Horsetail plant with cones, image: New South Wales Agriculture

Horesetail potted plant, © K. Bunn.

Horsetail spore producing cone or 'stobilus', © S. Welsh, NRE Tas.

Horsetail in Tasmania

Horsetail is not widely distributed in Tasmania but is reported occasionally as a weed of wet areas and ponds in domestic gardens. Horsetail occasionally appears in the nursery and herbal trade.
Horsetail can invade crops, pastures and native vegetation. Heavy infestations can reduce crop yields and pasture productivity, as well as poison stock.

What is the legal status of horsetail in your area?

The legal responsibilities of landholders and other stakeholders in dealing with horsetail are laid out in the Horsetail Statutory Weed Management Plan.
Use Table 1 (Zone A municipalities) in the Horsetail Statutory Weed Management Plan to find out whether this weed occurs in your municipality.

Detailed management and control guidelines for horsetail can be found in the Horsetail Control Guide. For further information see Weed Links and Resources.

Horsetail Control Guide

Horsetail is difficult to eradicate. Management will require a planned control program;
Contact Biosecurity Tasmania on 03 6165 3777 to confirm plant identity and help you plan a control program;
Consider the impact of your control methods on off-target species, especially if herbicides are used;
Ensure machinery and equipment is washed down between sites or prior to contractors leaving site;
Carefully time your use of herbicide for best results;
Revisit and regularly inspect the site and ensure follow-up is undertaken; and
Use a combination of different control methods.

Don't

Don't introduce horsetail to horsetail-free areas (e.g. by failing to wash down machinery and equipment between sites);
Don't start your control program without first planning your approach;
Don't allow horsetail to produce spore before treatment;
Don't rely on one attempt at removal - follow-up is essential;
Don't rely on just one control method.

Spread of horsetail

Horsetail spread is mainly by vegetative means. The deep rhizome system produces starch-filled tubers which bud off and produce new stems throughout the growing season.
New plants also form from rhizome fragments produced by cultivation and road-grading in infested areas, and through the cartage of contaminated soil.
Some spread also occurs via spores being carried by wind and water.

Physical removal

Small infestations of horsetail, if caught early enough, may be removed by digging out all plant material, including the rhizomes. In Tasmania infestations of scouringrush horsetail (E. hyemale) have been eradicated by excavation followed by deep burial of the material onsite.
For established infestations, physical removal by digging, slashing or mowing is not likely to be effective as horsetail quickly regenerates from any fragments of buried rhizome and tubers left behind in the soil.

Mulching

Mulching with a thick layer of leaf compost or black plastic can provide some benefit if maintained for long periods, but is unlikely to permanently remove an infestation.

Cultivation

Cultivation of the site is not effective as horsetail quickly regenerates from the buried rhizome and tubers.

Burning

Burning the above-ground horsetail is not effective as the buried rhizome and tuber material is not destroyed.

Chemical control

Horsetail is a deep rooted perennial. New shoots originate from rhizomes growing underground. The plant has little leaf area making it difficult to apply foliar herbicide and a high silica content which interferes with the uptake of many herbicides. Herbicide control of horsetail requires careful planning and advice.

Herbicides for Horsetail Control

No herbicides are registered for use on horsetail in Tasmania. Where new infestations are confirmed, contact Biosecurity Tasmania on 03 6165 3777 for help. This may include the provision of an off-label permit to allow herbicide application to this species.

Important Disclaimer

To the extent permitted by law, the Department of Natural Resources and Environment Tasmania (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using information or material (in part or in whole) contained on this website.