Horsetail preparation 508

What is the horsetail preparation (508)?

Field horsetail (Equisetum arvense) carries the preparation number 508 and has a special place among the biodynamic preparations: it is neither a compost preparation (502 to 507) nor a classic field spray in the sense of horn manure 500 and horn silica 501, but a plant care remedy for strengthening plants. Instead of maturing in a cow horn or an animal casing, it is boiled as a tea or decoction and sprayed preventively on soil and plants. The aim is to regulate fungal pressure, through the plant's high silica content.

This makes 508 the preparation that serves biodynamic plant protection from the preventive, strengthening side: it does not kill fungi but is meant to make the plant and the soil more resilient.

Field horsetail as a plant

Field horsetail is not a flowering plant but a spore-bearing plant like ferns and mosses, an ancient form of life whose relatives grew as tall as trees in the Carboniferous. A branched system of rhizomes grows far below plough depth. In spring, a pale, unbranched shoot appears first, made of interlocking segments with a club-shaped spore cone; the spores form moss-like prothalli with male or female organs. Only then does the green, sterile summer shoot grow up from the deep rhizomes.

Shoots and leaves consist of six-sided, rod-like segments that are rough and hard because of their high silica content. In the biodynamic understanding, it is precisely this silica, appearing directly in the plant, that is responsible for the fungus-regulating effect. An important distinction: marsh horsetail and wood horsetail are not suitable for the preparation. Field horsetail can be recognised by the internodes of the main stem being shorter than those of the side shoots.

Biodynamic context

In the biodynamic tradition, horsetail is understood as the silica-focused counterpart to the compost and manure side: while horn silica 501 lets the principle of silica and light work above ground through the plant, and the dandelion preparation 506 from the side of the manure, horsetail brings silica directly onto the soil and the crop as a plant strengthener. Its task is regulating fungi: in the biodynamic view it holds back "excess fungal growth" through its forces of light. Unlike the compost preparations, 508 stands outside the series of six and is used on its own.

Making it: tea or decoction

Collect the whole green, above-ground plant of field horsetail on a sunny day, ideally shortly before midsummer (end of June), and dry it spread very thinly in an airy, shady place. The finished dried herb should be green and is stored like tea in small airy bags.

For use, 200 to 300 grams of dried herb (or 1 to 1.5 kg of fresh herb) are simmered gently in 10 to 20 litres of water for about an hour. This decoction is used highly diluted: a 5 to 10 percent dilution is applied to soil and plants at about 100 litres per hectare. Besides the boiled extract, a cold-water brew (fermented for several days) is also common; the boiled decoction is the standard form described by Wistinghausen.

Use and timing

Horsetail has to be used preventively and repeatedly. It is not a remedy against an infestation that has already broken out, but a way of strengthening in advance. It is applied in autumn until well into November, in spring from February or March, and in high summer. In vegetable growing, the areas treated in autumn are preferably those that will carry crops prone to fungal disease the following year. Spraying the soil is often combined with a rhythmic application of horn silica to strengthen the plants from the side of light as well (see biodynamic farming practice).

The ready-to-use application is also widely known as horsetail tea: the same active material, with the name stressing how it is prepared.

Effect

In the biodynamic understanding, the high silica content of field horsetail regulates fungal pressure and strengthens plant health from the side of light. This effect is understood as strengthening and prevention, not as fungicidal killing. The assignment "silica holds back fungal growth" is a biodynamic view; independently of this, the high silicic acid content of Equisetum arvense is botanically established. Under plant protection law, horsetail extract counts as a plant strengthener or a basic substance, depending on how it is presented; health claims for people are not the subject of this entry.

In context

Field horsetail is one of the terms with a special place that can be explained in biological and geological terms rather than esoteric ones: an ancient, silica-rich living being whose material property (silicic acid) can be grasped objectively. The specific fungus-regulating effect in use is to be classed as biodynamic practical experience. For Demeter farms, preventive plant protection with horsetail is part of the established repertoire (see biodynamic farming practice).