Posted: 16/09/2012 at 12:25
There's no cure, Colin, not just for Late Blight but for any of the other fungal diseases. Once the spores have arrived and settled in - when the symptoms are showing - you can't kill them off. The same applies to most fungal garden problems - Black Spot on roses, etc.
All you can do is try to mimimise their effects after arrival or take preventive measures - prior to their arrival - by either spraying or undertaking the basic housekeeping procedures I've mentioned here so many times.