Abstract
Recently white rust of chrysanthemum caused by Puccinia horiana Henning became prevalent in those cultured under night illumination in vinyl house, in the Yame area of Fukuoka prefecture. The casual fungus produces both teliospores and sporidia on infected leaves. The optimum temperatures for germination of teliospores and sporidia were 18-28C and 13-18C, respectively. Two fungicides, ambam and piperazine, effectively inhibited sporidia germination of all isolates of the fungus while oxycarboxine was not effective against some isolates, suggesting that an oxycarboxine-tolerant strain might have developed among isolates collected from the Yame area.
