Urticae 500 | A spray preparation used in Biodynamics. It was created by Volkmar Lust in Germany and then further developed by François Bouchet in France. It takes its name from its two core constituents Horn Manure 500 and wild stinging nettle (Urtica dioica).
Why used | Urticae 500 helps (but cannot cure) vines affected by fan-leaf virus or for fanleaf degeneration (‘le court-noué’), and vines otherwise considered weak. It augments vegetative reproduction (leaf and shoot growth), and therefore photosynthesis, proving effective against chlorosis.
How made | Urticae 500 is prepared by diluting Horn Manure 500 with a tea made from stinging nettle (Urtica dioica) or willow (Salix alba). Pierre Masson describes one way of making Urticae 500 by preparing a stinging nettle tea from 100 grammes of dried nettles diluted in 4 litres of water, which is heated until the moment the water boils. After it has rested (macerated) for 24 hours, it is strained and diluted in another 35 litres of (warm) water. This diluted stinging nettle liquid then has the Horn Manure 500 added to it. The whole is then dynamized (stirred) for one hour and sprayed immediately or very soon afterwards. The amount of Horn Manure 500 used is 120, 240 or 480 grammes/ha (50, 100 or 200 grammes per acre).
How used | Urticae 500 is sprayed before flowering in spring and then again after the embryonic grapes have formed in early summer. It is sprayed on the upper or non-grape-forming part of the vine shoots and leaves and directly beneath the shoot’s apex (the vine’s nearest point to the sun). The Urticae 500 spray should not be mixed with Horn Silica 501 or Equisetum arvense 508.
L’Agriculture Bio-Dynamique by François Bouchet (Deux Versants, Paris, 2003), p162-3.
Guide pratique de la Bio-Dynamie à l’usage des agriculteurs by Pierre Masson (France, 1998), p11.