Organic viticulture – unintended consequences?

While I was in Central Otago in the south of New Zealand recently, I met Robin Dicey of Mt Difficulty. A South African farmer, he had been brought over to New Zealand by Corbans in Marlborough prehistory to advise them on grape growing and viticulture which is still his chief interest. (His son Matt makes the wines and, this year, chaired the Central Otago Pinot Noir Celebration.)

On a memorable drive in his silver Porsche through the Kawarau Gorge from Bannockburn to Queenstown past the bungee jump and Lake Hayes (pictured), he happened to mention his reservations about one...