Discovered in the late 19th century, Bordeaux Mixture was the world's first commercially successful fungicide. Among its achievements was the control of potato blight, the disease which had so famously devastated Irish crops earlier in the century. Although from the mid-1930s onward it was largely superseded in European and North Americn agriculture by progressively more sophisticated and expensive organic fungicides, Bordeaux Mixture, a simple mixture of copper sulphate and lime, remains a popular weapon for gardeners (Fig 1) and poorer Third World farmers fighting a range of foliar diseases. Modern formulation has improved its usefulness, there has been a lack of evolution of fungal resistance towards it and, above all, it has remained relatively cheap.