Amistar Xtra Acts as an inhibitor of mitochondrial respiration by binding to the Qo site of cytochrome b, disrupting the energy cycle within the fungus. Interrupts the biosynthesis of ergosterol Interferes in the fungal life cycle, mainly during spore germination, infection and hyphal growth Shows gradual uptake into the leaves Is xylem systemic, being transported acropetally and translaminary within the leaves.