Phosphatase-IN-1 (compound II-8), a propranolol derivative, is a phosphatidate phosphatase (Pah) inhibitor. Phosphatase-IN-1 can binds to MoPah1, with an affinity constant of 19.8 μM. Phosphatase-IN-1 inhibits growth of plant pathogens and shows anti-fungal ability. Phosphatase-IN-1 is not toxic to rice seedlings and wheat heads.