Plant extracts and their components have been reported to have antimicrobial properties against phytopathogens. Although such properties could be harnessed for the development of new pathogen control strategies, there are no standardised methods for their assessment in different extracts. The laboratory exercise presented here involves the use of chemical and microbiological techniques to determine the antimicrobial activity of natural products, such as essential oils, against phytopathogenic bacteria. It is aimed at candidates pursuing a PhD in Biological Sciences, but could also be suitable for students undertaking a UG degree, a PGT degree, or an MSc in the same field. In any case, students should be deft at handling microorganisms and complying with general lab work guidelines. This ought to ensure that the proposed techniques are understood easily and carried out safely. The nature of the exercises should allow for an integrative approach to the issue, which considers both chemical and microbiological aspects. It should also motivate students to critically appraise phytopathogen control strategies from an eco-friendly perspective.