Abstract
1. Twenty one isolates of rice blast fungus collected from 4 localities in Korea during 1962 and 1963, were differentiated into ten physiologic races on the basis of the reactions of Japanese 12 differential varieties and additional 2 varieties. These races were named tentatively as a, b, c, d, e, f, g, h1, h2, and h3.
2. Races a, d, and f reacted on the Japanese differentials as the Japanese races T-2, N-3 and T-3 respectively. Besides, both races b and h1, c and h2, and e and h3 reacted on the differentials as the Japanese race N-1, N-2 and N-4 respectively. The rest one, out of the ten, race g was similar in the reactions to that which had been reported, but not yet registered in Japan.
3. On the U.S. differentials, races b, c and d reacted as the U.S. races 6, 2 and 4 respectively. Besides, both races f and h1, and e and h3 reacted as the U.S. races 21 and 18 respectively. While, race a showed different reactions from the races reported by United States workers.
4. It was assumed that the race constitution in Korea was similar to that in Japan, according to the reactions of the tested isolates both on the Japanese and United States differential varieties.
