The designation according to the international system of pathogenic races of Phytophthora infestans and of genes for resistance to late blight in Japan.

Abstract

The pathogenic races of Phytophthora infestans isolated in Japan have been classified according to the international system of nomenclature, using a series of differential hosts of Dr. W. Black. Results obtained are as follows;
Domestic International
group 0 (H₁): race 0
group I (H₃): race 1
group II (H₂): race 4
group III (H₂, ₃): race 1, 4
group IV (BH₄): race 2
( ) Strains representing each group, and used in the former reports. As to genes for resistance, Takase's genes Ra and Rb have been found to be identical with international genes R₁ and R₄ respectively in their specific reactions to races of the fungus.