It does not matter if you are organic or not. All vineyards can suffer from various diseases. Against certain fungal diseases, downy mildew for example, you can spray with copper, usually in the form of copper sulphate. Both organic and conventional growers use copper but the conventional ones can also, or instead, use synthetic chemical products.
Copper is ultimately not good for the environment and the organic growers would love to find solutions to reduce their copper doses. They experiment with, for example, nettle, buckthorn and horsetail that strengthen the vine’s own defence system.
The use of copper in the vineyard is limited to a maximum of 6 kilo pure copper per hectare and per year (as an average over 5 years). This applies to organic farms. For conventional viticulture there is no limit. The 6 kilo limit is likely to apply in the EU until January 1, 2018. In France discussions are underway to lower the limit before that. A decision was supposed to have been taken back in May 2014 but has been delayed at least a year. It is worth noting that the biodynamic growers with Demeter certification can only use three kilograms of copper per hectare per year. More on copper in France: agriculture.gouv.fr