The present work describes the chemical composition of the leaf essential oils from the annual plant Dalea foliolosa, which was collected in three consecutive years (2014-2016). The amount of monoterpenes (69.5-84.6%) was higher to that of sesquiterpenes (10.3-22.9%) and aliphatic hydrocarbons (1-2.1%). Cryptone (22.3-30.6%) was the most abundant oxygenated monoterpene, followed by linalool (10.4-17.6%), caryophyllene oxide (4.6-15.3%), ascaridole (4.5-7.4%) and β-citronellol (3.8-5.6%). The hydrodistillated extract showed antioxidant activity against DPPH radical (IC₅₀, 45-156 μg mL^-1), strong anti-a-glucosidase activity (IC50, 14-47 μg mL^-1) and inhibited the growth of Pseudomonas syringae pv. tabaci TBR2004 (MIC, 44^-1 05 μg mL^-1) and P. syringae pv. tomato DC3000 (MIC, 35^-1 55 μg mL^-1). The possible use of the essential oil as a novel additive for anti-hyperglycemic supplements and for the biological control of the analyzed Pseudomonas syringae varieties, may be contemplated.