Bordeaux mixture has been banned by the EU since end of 2015. You might find it hard to get hold of. You can make it up yourself but I wouldn't bother. Copper content is high - not something you want getting into the soil/into your food. Never really understood how it could be termed organic.
As an alternative (that helps a little bit) you can increase the airflow between plants by removing the lower leaves once the fruit appears. This will also help them ripen as they'll get more sunlight.