HWY-289, a semisynthetic protoberberine derivative, exhibits broad-spectrum and potent activities against phytopathogenic fungi, especially Botrytis cinerea (EC 50 = 1.34 μg/mL). It alters the morphology of the mycelium and the internal structure of cells while decreasing ATP content, ATPase activities, and key enzyme activities in the TCA cycle [1].