Sustainable Crop Protection, Global Climate Change, Food Security and Safety—Plant Immunity at the Crossroads

The development of novel strategies of plant disease management is crucial in view of the growing demand of sustainability in agri-food chains. The use of agrochemicals is not without risk for the consumer and environment in terms of their residues in food, feed, water bodies and harmful effects on nontarget organisms. However, because of the high global annual yield losses attributable to plant diseases and also due to global climate changes that have exacerbated some phytosanitary emergences, chemical input in agriculture is mandatory. In this complex scenario, the use of agrochemicals that boost the plant immune system represents a relatively novel approach in crop protection. These plant protection products are not antimicrobial or fungicidal agents, but include both natural and synthetic elicitors and plant activators that only target the host immune system, with no biocide mechanism of action. In general, these products present a number of strengths: they leave no residue and should not select resistant pathogen strains, they can be used to control virus diseases, and can increase the levels of bioactive phytochemicals in plant foods.