Effect of Medium and Planting Data on the Occurrence of Leaf-yellow-spot in Chrysanthemum 'Seikounomakoto'

Effects of medium and planting data on the occurrence of leaf-yellow-spot in chrysanthemum 'Seikounomakoto' Dendranthema grandiflora Kitamura were investigated. Long duration was required until occurrence of leaf yellow-spot. Moreover, advance of leaf-yellow-spot was slow. The occurrence of leaf-yellow-spot was remarkably increased by sandy loam soil, but decreased by peatmoss and sand medium. Regardless of medium, pattern of occurrence of leaf-yellow-spot was similar. The occurrence of leaf-yellow-spot was attected by planting date, and was remarkably increased by high temperature and irradiation, but decreased by low temperature affected the occurence of leaf-yellow-spot