ABSTRACTS.- The efficacy of natamycin (Fruitgard Nat 20) and Proallium (an extract of allium including propyl thiosulfinate oxide (PTSO)) against sour rot and green mold in mandarins was evaluated under controlled and commercial conditions. The study involved artificial inoculation of Nova, Tango, Orri, Afourer, Murcott, and Nules Clementine mandarins with isolates of Penicillium digitatum resistant to imazalil and pyrimethanil and an isolate of Geotrichum citri-aurantii susceptible to propiconazole fungicides. © 2024 by the authors. Licensee MDPI, Basel, Switzerland.