Abstract
An index to the bad rice harvest, Icd, in the Tohoku district, northern part of Japan, is defined according to Hatake's table. A comparison between Icd and annual growth rate of the tree-ring of a zelkova felled in Yamagata shows that the large variation of Icd reflects the change of natural weather conditions.
Bad harvest years are objectively defined using Icd, and superposed epoch analysis is applied to the study of the relationship between bad harvest and solar activity. The results show an increase of bad rice harvest about one year after the sunspot minimum. The growth rate of the zelkova also has a small maximum around the sunspot minimum.
