Root Diseases of Spinach in Plastic House Cropping and their Pathogens

Abstract

In moutainous and cool summer districts in and around Takayama City in Gifu Prefecture, the occurrence of root diseases of spinach (Spinacia oleracea L.) and their pathogens in plastic house cropping were studied during the growing season from May to October, 1977. The pathogenic fungi isolated most frequently from the diseased plants were Fusarium oxysporum f. sp. spinaciae and Rhizoctonia solani, followed by Pythium spp. Aphanomyces sp., Fusarium solani and binucleate Rhizoctonia sp. were additional ones which were isolated less frequently from the diseased plants. The occurrence of the diseased plants was less frequent in May and October, the beginning and the end of cropping season, respectively. Conversely, damping-off of the seedlings in 2-4 leaf-stage caused by R. solani was most serious, followed by Rhizoctonia foot rot and Fusarium wilting of spinach in more than 5 leaf-stage. The differences of the isolation frequency of the pathogenic fungi and the incidence of the diseased plants were found among the fields which varied in their cropping histories and soil textures.