Horsetail, or Equisetum, is a perennial plant belonging to the Equisetaceae family, found in Eurasia and North America. Easily recognisable by its green, hollow, ribbed and jointed stems, it stands with natural elegance. Its silhouette, sometimes compared to a horse's tail, bears witness to its robustness and adaptability, allowing it to reach heights of 30 centimetres to one metre depending on the variety. Beyond its unique appearance, horsetail has long been recognised for its beneficial properties, particularly in organic farming.

A comprehensive definition of this plant

Horsetails are vascular plants without flowers or seeds. They reproduce by spores and have underground rhizomes that allow them to spread and persist from one year to the next. They are particularly rich in silica, an essential element for strengthening plant tissues. It is this unique composition that gives horsetail its protective and fortifying virtues, which are especially valuable in the context of environmentally friendly agriculture.

A major agronomic objective: vine protection

The use of horsetail in viticulture is part of a preventive approach against various fungal diseases, foremost among them downy mildew. Thanks to its high silica content, horsetail helps to strengthen the cell walls of the vines, making them less vulnerable to pathogen attacks. It acts as a genuine natural shield, stimulating the plant's intrinsic defence mechanisms and reducing the need for synthetic plant protection products. This approach contributes to better biodiversity and the overall health of the vineyard.

Key moments for applying horsetail in the vineyard

The effectiveness of horsetail is maximised when applied preventively at key moments in the vine's vegetative cycle. Generally, the first applications take place as early as bud break and continue until bunch closure. Regular treatments, spaced 7 to 15 days apart depending on disease pressure and weather conditions, ensure continuous protection. At Château Cazebonne, these applications are fully integrated into our calendar of vineyard work, tailored to our biodynamic approach.

Preparation and application of horsetail tea

Horsetail is most often used in the form of a tea, an aqueous extract obtained by maceration or decoction. The steps are as follows:

• Harvesting: The aerial parts of the horsetail are picked, preferably during full growth, to maximise their silica content. They can be used fresh or dried.
• Preparation: Approximately 100 to 150 grams of fresh horsetail (or 15 to 20 grams dried) are soaked in one litre of rainwater for 24 hours.
• Decoction: The mixture is then brought to a boil and left to simmer over low heat for about 30 minutes.
• Cooling and filtering: After cooling, the preparation is filtered to remove plant residues.
• Dilution: The resulting tea is generally diluted to 10 or 20% in water before being sprayed onto the vine canopy.

Equipment required for application

To prepare and apply the horsetail tea, the equipment is simple:

• Gloves and secateurs for harvesting.
• A large container (preferably non-metallic) for soaking and decoction.
• A heat source.
• A fine filter (cloth, sieve).
• A sprayer suited to the size of the vineyard, like those used for other biodynamic teas and natural preparations, or for preparations such as nettle manure.

Horsetail, a pillar of organic viticulture at Château Cazebonne

At Château Cazebonne, integrating horsetail into our cultivation practices is a concrete example of our commitment to sustainable and organic viticulture. It represents a natural and effective alternative to conventional treatments, aligning with our philosophy of preserving both the soil and the vine. By combining the use of horsetail with other agroecological methods, we promote a natural balance and strengthen the resilience of our vineyard against climatic and health challenges. In doing so, we contribute to the health of our plots and the authentic expression of our Bordeaux terroir.

This meticulous work of preservation and innovation is not limited to our cultivation practices. It also extends to the replanting of forgotten grape varieties, those varieties that created the wealth and diversity of Bordeaux wines before their standardisation. This ambitious project is documented in the book "Bordeaux, une histoire de cépages", which you can download for free. To test your knowledge of the wine world and our estate, feel free to explore our oenological quizzes, and of course, to discover the unique expression of our terroir through our different cuvées, available now in the Cazebonne boutique. It is thanks to the enthusiasm and unwavering support of all the wine lovers who have embraced our wines and shared our vision that this work is made possible.