Colletotrichum acutatumによるナシ炭疽病の発生と防除薬剤の検索

抄録

In late August 1998, leaf blight symptoms of anthracnose disease and preharvest defoliation were found on ‘Kousui’, the most popular cultivar (cv.) of Japanese pear, in several orchards in Akita Prefecture, Japan. The fungus isolated from diseased leaves was determined to be Colletotrichum acutatum Simmonds ex Simmonds, based on temperature relationship of the colony growth, colony characteristics and conidial morphology, as well as its lesser sensitivity to the fungicides benomyl and diethofencarb added in potato dextrose agar. This is a new anthracnose pathogen on Japanese pear, in addition to Glomerella cingulata (Anam.: C. gloeosporioides) hitherto known to cause anthracnose disease on Japanese pear. The isolates of C. acutatum were pathogenic to the leaves of Japanese pear ‘Kousui’, ‘Housui’, ‘Choujuurou’, ‘Nijisseiki’, ‘Yasato’ and others in artificial inoculation tests. The strobilurin fungicides, azoxystrobin (100 μg/ml) and kresoxim-methyl (235 μg/ml) effectively controlled the disease in field experiments.