Soil fumigation and crop rotation to control spraing disease in potatoes

Growing resistant potato cultivars is of little help in avoiding damage by spraing, because of regionally differing strains of tobacco rattle virus and of special requirements of the processing industry. On soil, fumigated in 1971 during autumn with a solution of dichloropropene-dichloropropane (660 g/l) at 250 l/ha, the vectorsTrichodorus spp., were effectively controlled and the tuber disorder did not appear in the next year's potato crop. But potatoes from the treated plots had an unacceptable off-flavour. In the second crop after treatment, control was still good and there was no difference in flavour between potatoes from treated and untreated plots. Disease incidence was significantly lower after spring barley than after sugarbeet, maize, or potatoes.