The present study has been designed to evaluate the phytochemical quality and quantity of the essential oil (EO) extracted from Cladanthus eriolepis originated in Southern Moroccan oases and to examine its antimicrobial potential by the use of poison-food (PF) and volatile activity (VA) tests against four bacterial and five fungal agricultural pathogens. The analysis of the EO showed that camphor was the predominant constituent (37.02 %), followed by sabinene (10.26 %), α-pinene (6.29 %), p-cymene (6.13 %) and α-cadinol (5.57 %). The antimicrobial activity of C. eriolepis oil in vapor and liquid phases on the tested bacterial and fungal strains showed that Staphylococcus aureus ATCC 6538 was the most vulnerable, displaying the weakest development with a minimal bactericidal concentration (MBC) and minimal inhibitory concentration (MIC) of 0.156 mg mL-1 and 0.078 mg mL-1 respectively. Fusarium oxysporum f. sp. albedinis, Aspergillus brasiliensis, Rhizopus stolonifer, Penicillium expansum and Alternaria sp. were found to be susceptible to this EO, thus were partly repressed with 0.5 μL mL-1 of the liquid EO. Nevertheless, at the same concentration, mycelial growth of Rhizopus stolonifer and Alternaria sp. was completely inhibited by the vapor phase of the EO. The latter has a higher antifungal activity which can inhibit the growth of most tested fungi. This behavior of the vapor phase provides an interesting path forward for finding ways to apply this EO especially by fumigation in the control of post-harvest diseases.