Abstract
Barley Yellow Mosaic Virus (BaYMV) is one of the most important virus in barley in Japan. UsUGI et al. (1985) identified BaYMV strain I and II based on their pathogenicity to two-rowed barley cultivars, Haruna Nijo and Amagi Nijo. Recently, an BaYMV isolated that infected two-rowed barley cultivar Misato Golden, resistant to strain I and II of BaYMV, was found at lbaraki prefecture and named as strain III. Based on field reactions of six barley indicator cultivars, fields where two-rowed barleys were planted for more than 3 years were found to be infested with strain I (Table 2). Fields where susceptible six-rowed barley cultivar, Kashimamugi, wa, s planted for more than four years or susceptible two-rowed barley cultivars were planted for less than two years were found to be infested with strain II (Table 2).
