Mares Tail or Horsetail

Mares Tail or Horsetail - Toxic to Horses...

Mares tail, also called horsetail and scouring rush, poisons your horse in a similar fashion to bracken fern. All varieties of Mares tail are poisonous and they are often found near bogs and streams.

The term 'scouring rush' is due to the fact that the coarse stems were used to effectively scour dirty cooking pots. Mares tail has a high concentration of silica in its tissue and sixteenth century Europeans used these scouring reeds to scrub pots and polish furniture. Native Americans and pioneers used mares tail to clean cooking utensils; some camping enthusiasts still use it for that purpose.

Horsetail - Plants Toxic
to Horses

Mares Tail is a Herbaceous, perennial, leafless plant with a hollow stem that readily separate at the nodes.

The leaves are reduced to papery scales with black tips that surround the stems at each node. The stems are cylindrical, ridged and rough to the touch due to the high silicate content.

There are 2 types of stem.

Fertile stems are unbranched, and are tipped by a cone-like structure containing spores.
Infertile stems have multiple whorled branches at the nodes.

Mares Tail reproduces from both the deeply buried rhizome and from its spore bearing cones. These cones contain millions of spores.

The plant contains Thiaminase, which is the suspected toxin and also contains aconitic acid, polustrine and silicates. Mares Tail is rarely eaten except when dried in hay, but all species should be considered potentailly toxic to horses.

Dried Mares Tail

Most poisoning occurs when horsetail is cut and incorporated into hay which is then fed to horses and other livestock.

However, Mares Tail can remain green during the winter months and it may be eaten by horses if good grazing is in short supply.

Mares Tail (Equisetum palustre) the Facts

Mares Tail Equisetum palustre Equisetum palustre is poisonous to herbivorous animals, but not to humans.

It contains a vitamin B1-destroying enzyme which makes horses tumble, as well as the piperidine alkaloid palustrine, which can lame cattle.

Both of these substances are stable for years.

Mares Tail produces millions of spores in the summer.

The spores are spread by the wind (anemochory) and have four long ribbons attached to them. They sit on spore ears which are rounded on the top.

Suspected Mares Tail Poisoning.

Horses suspected of mares tail poisoning should immediately be taken off the hay or pasture containing the Equisetum and fed a nutritious diet.

Treatment with thiamine hydrochloride (1-2 mg/kg subcutaneously for several days) is beneficial in restoring thiamine levels to normal.

Feeding grain as part of the diet can produce a protective effect against the thiaminase.

Symptoms of mares tail poison :

Weakness and uncoordinated hind legs progressing to recumbencing.
Animals continue to eat relatively well.
Once the horse is down and cannot get up, the prognosis is poor because of muscle degeneration;
Horse may appear blind and have difficulty in seeing;
Central nervous system depression develops in the more severely poisoned horse;
Blood pyruvate levels may be elevated.

Horse or Mares Tail - Eradication

Horse or Mares Tail, Equisetum Palustre should be the equestrians public enemy number one. It looks like it belongs in Jurassic Park and, unchecked, spreads like wildfire.

Mares Tail Sprouts in the Spring I’d recommend NOT digging mares tail out until it is dead for sure. Otherwise it just starts springing up from the root cuttings. Drying or drowning the roots prior to composting is a must.

In spring, brown green shoots appear with small cones at the tips that produce spores, millions of them, and it grows away from creeping thin brown roots that you can hardly see as they are soil coloured. Digging out these roots is not feasible as they go down into the soil for up to 1.5 metres – yes, 5 feet.

Later the leaves or tails appear. These will die off as Autumn turns to Winter and the roots sit there waiting for spring.

The leaves have a waxy coat, which makes the plant highly resistant to weedkillers.

Crushing the leaves to break up the coating helps weedkiller to penetrate and become absorbed but in large areas it is not so easy to crush all the leaves. However, glyphosate weed killer will have an effect and eventually kill the plant.

You will probably need 5 or more applications. Knock it back, wait until it re-grows and then repeat.

It's doubtful you can clear mares tail in one season.

Never touch Mares tail with a mechanical cultivator. If you do you will quickly understand why it has been around for 60 million years.