Polemics around the copper.
Copper only possible treatment against organic mildew is currently the subject of great controversy, it would be, according to some, harmful to the environment. These argue that in large quantities it would be subject to reduction and would no longer be assimilable, therefore toxic. But copper is not part of heavy metals and cannot be "reduced"!
Besides, the annual consumption per hectare is limited in organic agriculture to an average of 5 Kilos maximum per year over 5 years. (For example our average in Fougas over this period is 3 Kilos / Hectare per year!).
It is true that in conventional viticulture (non-organic) wine growers use for a single treatment 5 kg / ha. What makes a consumption for 10 annual treatments of 50 Kg / Ha !!!
Multiplying by 10 the maximum annual consumption allowed in organic.
In organic viticulture copper is regularly assimilated by soil micro-organisms, and analyzes confirm the total absence of copper in soils.
In biodynamics, in addition to copper, we also use horsetail decoctions to control downy mildew.