Abstract: Bioactive synthetic peptides can be designed based on structure-function approaches, departing from natural compounds, and their activity, action range and toxicity can be improved using combinatorial chemistry. Lytic peptides have the capacity of producing damage in the cell membranes, both in bacteria and fungi, and have shown control of diseases caused by bacterial, fungal and phytoplasm plant pathogens. Cell penetrating peptides can be used to deliver cargo molecules to target specific intracellular structures in plant cells. Plant defence elicitor peptides based on the pattern triggered immunity (PTI) system can be designed and their topical application to plants enhances the resistance to pathogen infection. Synthetic peptides can be produced in microbial or plant biofactories. The rice seed endosperm can be used for sustainable production of functional peptides with reasonable yield. It is expected that the properties of bioactive peptides fulfil the current regulation of “low-risk pesticides” in the EU, and could contribute to a novel type of sustainable pesticides.