Willow decoction is a plant-based spray made from the shoots, leaves, or bark of the white, common or European willow tree (Salix alba). The willow grows in humid riverbank conditions yet never suffers mildew, so its main role is anti-fungal (downy mildew, powdery mildew, botrytis), a role it shares with both the common horsetail (Equisetum arvense) 508 spray preparation and oak bark decoction–but being easier to harvest than the latter because more than simply the bark can be used. Willow’s active ingredient is salicin. In the human body salicin converts into salicylic acid, the forerunner of aspirin but without the latter’s stomach-irritant effect. Salicylic acid levels are highest in willow in spring which is when plant material should be collected (Pierre Masson: 2014, p.113). Willow is popular amongst wine-growers with grape varieties highly susceptible to downy mildew like Grenache Noir.

Plant material from both willow and stinging nettle is often combined when making vineyard teas and liquid manures, although willow seems more adapted to decoctions (subjected to simmering) than stinging nettle.

See also the Urticae 500 spray developed by François Bouchet.

Bibliography

Monty Waldin, Biodynamic Gardening (Dorling Kindersley, 2015).

Monty Waldin, Biodynamic Wine (Infinite Ideas, 2016).

Pierre Masson, Guide pratique de la Bio-Dynamie à l’usage des agriculteurs (France, 1998).

Pierre Masson, A Biodynamic Manual (second edition, 2014, Floris Books, Edinburgh), revised and edited by Pierre and Vincent Masson. Translated by Monique Blais.