Variety mixturs as a mean to control tuber blight in potatoes?

The aim of the European Community of prohibiting the use of copper in agriculture promoted the research for new strategies to control potato late blight (Phytophthora infestans) in organic farming. The cultivation of mixtures of different potato varieties could be a promising mean to control late blight. In a field trial at Reckenholz in Zurich, complete mixtures of different varieties only slightly reduced Phytophthora infestations on the potato leaves. Better results were observed, when the varieties of the mixtures were grown in alternating rows. In contrast to the effect on leaf blight, tuber blight was reduced by up to 50 %. Again the cultivation of the different varieties in altering rows was more effective than the procedure with a total mix of the varieties.l’infestation que la culture avec un mélange total de variétés.