Phytophthora species, classified under Oomycota, cause significant damage to various cropsand trees. The present study introduced Phytophthora species, P. nagaii and P. tentaculata,new to Korea, which pose notable risks to their respective host plants. Our research provideda comprehensive description of these species taking into account their cultural features,morphological characteristics, and molecular phylogenetic analysis using the internaltranscribed spacer rDNA region and cytochrome c oxidase subunit mtDNA genes (cox1 andcox2) sequences. In addition, this study first evaluated the sensitivity of P. nagaii and P. tentaculatato five anti-oomycete fungicides, finding both species most responsive to picarbutrazoxand P. tentaculata resistant to fluazinam. The data can guide targeted treatmentstrategies and offer insights into effective control methods. The findings expand our understandingof the diversity, distribution, and management of Phytophthora species in Korea.