Abstract
Two tests were carried out to determine the difference among cultivars in winter hardiness and its relation with fall dormancy, leafy disease, plant survival and productivity in Konsen district with cool and humid summer and severe winter. One hundred ten cultivars collected from areas with contrasting environments. Their growth types, proposed by SUZUKI et al. belonged to the types III, VI and V. (1) Frost heaving and snow mold injury were not observed but large difference among cultivars in winter injury was found after the second year. It was suggested that the winter injury was resulted mainly from the freezing. (2) The winter hardiness estimated by winter injury was negatively correlated with fall dormancy(r=-0.60^<**> in exp.1, -0.85^<**> in exp. 2) and positively with resistance to leafy disease (r=0.61^<**>, 0.84^<**>). This indicates that cultivars resistant to the winter stress in Konsen district are characterized by comparatively vigorous fall growth and resistance to leafy disease, particularly Lepto-leaf spot (Leptosphaerulina briosiana). (3) Winter hardiness was also negatively correlated with spring vigor (r=-0.91^<**>, -0.95^<**>), first crop (r=-0.72^<**>, -0.78^<**>), and stand coverage (r=-0.85^<**>, -0.89^<**>). Winter hardiness is considered to be a limiting factor of productivity and plant survival in Konsen district.
