We analyzed the molecular responses of pepper and tomato leaf tissues after infection with P. sojae and treatment with KACC 40557 extract. The percent total infection was measured up to 96 h after treatment (Fig. 3). Severe damage was observed in pepper leaves from 72 h after treatment in AP (24%), while no significant damage was detected in PDE (1%) and EP (0%). The damage was increased by up to 62% in AP 96 h after treatment, while there was minor damage in EA (2%) and no damage in EP (0%). Severe damage was observed in tomato leaves from 48 h after treatment in AP (35%), while small spots were detected in EA (2%) and EP (2%). The damage was accumulated up to 74% in AP 96 h after treatment, while minor damage was observed in EA (4%) and EP (10%). These results indicate that the extract functioned as an anti-Phytophthora compound against P. sojae in pepper and tomato leaves without severe harmful effects on the plants. Anti-Phytophthora activity was more efficient in pepper leaves than tomato leaves, possibly due to the different interactions between plants, pathogens and extracts. The same leaf tissues were used for the analysis of plant hormones.