Field horsetail – a mare to get rid of!
By Jennifer Holmes

Field horsetail – a mare to get rid of!

Horsetail – the living fossil that is…

Yes, that’s right, as well as being a native invasive species, Field horsetail is a “living fossil”, because for over one hundred million years Horsetail weeds were more diverse and dominated the late Paleozoic forests. It’s also the only living genus in the Equisetaceae family of vascular plants which reproduce by spores rather than seeds. Horsetail (scientific name: Equisetum Arvense)  herbaceous perennial plant, sometimes incorrectly referred to as Marestail (or Mare’s Tail) is commonly found in gardens, alongside roads and pathways in urban areas, and as the name suggests can also be found in pasture land or fields designated for horses.


a danger to horses

Apart from the environmental impact of Horsetails – it quickly takes over grassland areas, as its name suggests the horsetail plant is extremely dangerous to grazing horses, as it inhibits production of vitamin B1. There are many symptoms of Horsetail poisoning in horses which includes an unusually scruffy physical appearance, weight loss, diarrhoea, uncoordinated movements, loss of muscular control, staggering gait, balance issues, seizures and eventually death from exhaustion. As well as being harmful to horses, cattle, sheep and livestock. The plant is poisonous in both the green state and dried in hay. Maximum vegetative growth of field horsetail occurs in July.

It may be a surprise then to learn that Horsetail is safe for human consumption – either cooked or raw, though apparently it has little or no taste!

Field Horsetail

tough and prolific

This is an extremely resilient and tough plant, some would say virtually indestructible – it only takes two or three of these harmless-looking horsetails to quickly overwhelm a large planted area, forming a dense carpet. Not only does it grow prolifically in fields and grass areas (including gardens) but even on tarmacadam surfaces that have been unknowingly laid over untreated Horsetail infested ground this plant can penetrate through the surface and cause damage. It will quickly out-compete other plants if not controlled, especially so in fields and pasture land, which depletes natural fodder for cattle and livestock.


and hard to get rid of.

How to get rid of horsetail weed UK. Horsetail grows via underground rhizomes which can reach as much as 2m (7ft) below the surface. Getting these roots out requires hand digging or excavation. As with all rhizome plants they can run underneath boundaries causing problems of encroachment on neighbouring properties or land. If you have Horsetail in your garden regular digging it all out may not be a permanent solution as any root fragments left in the ground will form new plants. Suppressing the rhizomes with a barrier in the upper layers of soil is not completely effective as the emerging vegetative stems can penetrate some barrier materials. Horsetail can also survive periods of flooding and burning but can be sensitive in drought conditions.


Field horsetail

What to look for

Horsetail is derived from huge, tree-like plants that thrived 400 million years ago during the Paleozoic era. It is a close relative of the fern, the plant is a perennial (returns each year) with hollow stems and shoots that look like asparagus at first.

Horsetail is easily recognised throughout the Summer and Autumn by its upright light green, fir tree like shoots with folded needle like leaves pointing upward around the stem.

Field horsetail stems

Its characteristic stems have cone shaped heads that can grow up top 20cm high. The heads are in fact clusters of small spore pods. Horsetail lies dormant over winter, so Summer is the best time to identify it, via a professional survey, as it will need a highly trained eye to spot it in it’s early awakening.


Unusual fact!

Towards the end of its growing season the plant dries and silica crystals in the stems and branches appear like feathery tails that are quite harsh to the touch. This property resulted in Horsetail being popular as a metal polishing substance – in particular pewter.

Need help with Horsetail?

So how do you kill field horsetail? Whether you own horses or have livestock on your land, Horsetail is a plant not to be ignored. We have been called out almost as an emergency by stable owners finding Horsetail in fields their horses use to graze in. If you have it growing in your garden it will most likely take over your turf if left uncontrolled. The best option is to have a survey carried out so we can identify it correctly and put together a programme for treatment or eradication.

Speak to the team