The decoction and maceration of horsetail are two highly effective natural fungicides and insecticides. The plant, also known as horsetail, grows wild and is widely distributed in our country. In reality, the genus Equisetum, belonging to the botanical family Equisetaceae, comprises about 35 species. However, only about ten of these are common in the Italian flora. These plants are classified among the oldest organisms present on Earth. The discovery of fossil remains dates their presence back to the Devonian period, almost 400 million years ago.
Let’s get to know this plant better, which is so important for biological defense against cryptogamic diseases and plant pests.
The Horsetail Plant

Equisetum arvense
Before understanding how to prepare the decoction and maceration of horsetail, let’s take a closer look at the plant.
The species we are discussing is Equisetum Arvense, commonly known as field horsetail, a perennial and wild herbaceous plant. The term “arvense” refers to its primary habitat, which is fields, especially wet and uncultivated areas in mountainous regions. This variety is the most common in circulation. It is used not only in organic farming but also in herbal medicine as it possesses many medicinal properties.
Peculiarities
The horsetail plant has a fairly complex structure. One of its peculiarities is being a rhizomatous geophyte, meaning a perennial that carries its buds deep into the soil. During the winter months, to survive adversity, it does not have aerial organs. During this period, the buds survive in underground organs called rhizomes. This is the hypogeal part of the plant.
Fertile Stems

Fertile stems
From the rhizomes, starting in early spring, the aerial organs of horsetail (the epigeal part) are formed, namely the stems. These can be of two types: fertile and sterile.
Both types have longitudinal grooves and are divided into different nodes and internodes.
The fertile stems of the plant emerge in spring and have a reproductive function. Their color is brownish-white, sometimes tending towards yellow, and they lack chlorophyll. They are unbranched but have nodes and internodes, with an apical part called the strobilus. The spores, the means of horsetail reproduction, are housed inside the strobilus. This type of stem sporulates (i.e., releases spores) in spring.
Sterile Stems

Sterile stems
After the dispersion of its spores, the fertile stem dies, giving rise to the sterile stem, known as the summer stem.
The sterile stem is green in color as it is rich in chlorophyll.
It has a rough surface and is branched, with about a dozen branches arranged in whorls at the base of the leaves. The leaves are not very significant and are positioned at the nodes of the stem, forming a sort of sheath. Its height can reach up to a maximum of 60 cm.
These are the parts of the plant that should be used for preparing the decoction and maceration of horsetail.
Other Horsetail Species

Marsh horsetail
As mentioned earlier, there are various varieties of horsetail, some of which may resemble each other.
The Equisetum Arvense, we must emphasize, should not be confused with other similar species, such as the marsh horsetail. Paying close attention to the difference between the two plants is important because the latter contains toxic alkaloids like nicotine and palustrine, which can cause harm if accidentally ingested.
Therefore, if you intend to prepare a decoction or maceration of horsetail, and you are not sure of the species, seek advice or a comparison from experienced individuals who can help you identify it.
Content and Properties of Horsetail
The main constituents of horsetail are: salicylic acid, silica, oxalic acid, sulfuric salts, modest amounts of alkaloids, flavonoids, equisetin, and other mineral substances such as calcium, potassium, aluminum, magnesium, and manganese. Silica content is high (about 17% of the ashes), and together with the presence of other elements, it makes it an excellent natural fungicide for biological defense against cryptogamic diseases such as powdery mildew or downy mildew. Equisetum-based solutions can strengthen the leaf cuticles of vegetable crops, making it more challenging for pathogens to establish fungal diseases, usually transmitted through the deposit of spores on the plant’s leaves themselves.
At the same time, applying the solution to the leaves acts as an effective repellent for many garden pests, including aphids and mites.
The Decoction and Maceration of Horsetail
The most common preparations that can be made with the sterile stems are: the maceration of horsetail and the decoction of horsetail.
For both preparations, the following dosage applies:
- 1 kg of green plant (or 150 g of dried plant)
- 10 liters of water
Preparation of the Maceration of Horsetail
To prepare the maceration of horsetail, soak the desired amount of green plant for 7-10 days. Once soaked, horsetail starts to ferment and produce foam. When the production of foam stops, the maceration is ready and can be filtered. For maceration, it is recommended to use terracotta containers or, at most, hard plastic ones. Avoid metals and fiberglass. Also, position the container in a shaded place.
For storing the maceration, dark-colored glass bottles are recommended. Once the maceration of horsetail is prepared, it can be diluted in an additional 5 parts of water.
Preparation of the Decoction of Horsetail
To prepare the decoction of horsetail, put the desired amount of green plant in a pot with water and let it rest for 24 hours to reduce its volume. Then, heat the pot over low heat until it reaches boiling point. Once it reaches boiling point, turn off the heat, let it cool, and then strain it.
The decoction can also be diluted in an additional 5 parts of water.
Using the Decoction and Maceration of Horsetail on Plants
The maceration of horsetail, like the decoction, is useful for the biological defense of plants. Using a convenient backpack sprayer (if you don’t have one, you can find it here), always during the cooler hours of the day, you can spray one of the two solutions directly on the leaves and on the ground.
To improve the effectiveness of horsetail-based preparations, you can add sodium silicate. The latter is recommended because it increases the efficacy and persistence of horsetail on leaf laminae. Of course, sodium silicate is a product permitted for use in organic farming. If you want to add it to your decoction or maceration, you can purchase it here.
Another addition that can be made to enhance the effectiveness of both the decoction and maceration of horsetail is Marseille soap. This improves the adhesiveness of the solution.
To protect against fungal diseases, both the maceration and decoction can be sprayed on the plants every fifteen days. If environmental conditions tend to favor the proliferation of the disease, for example, during a period of alternating rain and intense heat, you can increase the frequency.
Finally, if used as an insecticide, horsetail can be used together or alternately with other natural preparations such as nettle maceration, garlic infusion, and maceration of tomato leaves and females.
Further Reading
- Nutrients – Inhibition of 5α-Reductase, IL-6 Secretion, and Oxidation Process of Equisetum debile Roxb. ex Vaucher Extract as Functional Food and Nutraceuticals Ingredients – This study investigates the biological activities of Equisetum debile extracts, including 5α-reductase inhibition, interleukin-6 (IL-6) secretion reduction, and anti-oxidation. The extracts were obtained by maceration in various solvents, and the results suggest potential applications in functional food and nutraceuticals.
- Planta Med – In Vitro Anti-inflammatory Effects of Equisetum arvense Are Not Solely Mediated by Silica – This study explores the anti-inflammatory effects of common horsetail (Equisetum arvense), focusing on the role of silica and isoquercitrin. The findings reveal potential therapeutic applications for inflammatory diseases.
- Eksp Klin Farmakol – Hepatoprotective effect of plant preparations – This research investigates the hepatoprotector activity of plant compositions containing common horsetail herbs, beet and carrot juices, and other extracts. The study was conducted on an acute hepatitis model, showing promising results.
- Braz J Biol – Ethnomedicinal and traditional uses of the Ferns of Khyber Pakhtunkhwa, Pakistan – This article documents the traditional uses of various ferns, including Equisetum, in Khyber Pakhtunkhwa, Pakistan. It highlights the importance of these plants in local ethnomedicine.