The chemical composition of the seasonal essential oils (2015-2016) from the leaves and flowers of Zaluzania montagnifolia is presented. The chemical content of those oils showed quantitative and qualitative differences. Germacrene D (19.9-29.8%), camphor (12.4- 19.4%) and β-caryophyllene (13.7-18.5%) were the most abundant volatiles in the leaves. The essential oils from the flowers contained high amounts of camphor (32.7-37.2%) limonene (19.8-24.9%) and germacrene D (3.2-7.3%). All the seasonal essential oils showed a potent in vitro inhibition against HMG-CoA reductase. The essential oils from flowers (IC50, 40.5-55.1 μg mL-1) showed better inhibition properties than those of leaves (IC50, 84.4-123.5 μg mL-1). Camphor (IC50, 72.5 μg mL-1) and borneol (IC50, 84.4 μg mL-1) exerted a non-competitive inhibition on the enzyme. Additionally, the hydrodistillates exhibited antibacterial activity against the phytopathogenic Pseudomonas syringae pv. tabaci TBR2004 (MIC, 62.7-76.5 μg mL-1) P. syringae pv. tomato DC3000 (MIC, 45.4-50.4 μg mL-1) and P. syringae pv.phaseolicola NPS3121 (MIC, 26.7-31.9 μg mL-1). Germacrene D (MIC, 35.4-66.2 μg mL-1) and β-caryophyllene (MIC, 36.5-54.2 μg mL-1) were the strongest anti-Pseudomonas syringae agents.