One of organic agriculture’s defining traits is its approach towards plant health care, relying mainly on preventive and indirect measures within the agroecosystem. As a last resort, organic farmers can combine these with direct measures, if these are based on the use of natural substances. The principles of organic agriculture seek to prevent the introduction of new and alien substances into ecosystems. So, the use of synthetic pesticides is prohibited. More and more European citizens are concerned over synthetic pesticides use.

Resurgent pests or invasive exotic pests (e.g., two new species of mealybugs, or the Trioza erytreae, transmitter of the Huanglongbing disease (HLB)) are major challenges of the Mediterranean citriculture). The solution could be to increase the presence and prevalence of natural enemies of pests through the introduction of plant biodiversity such as perimeter hedges, ground covers and flower strips.

The reduction of copper-based plant-protection products with the final aim of phasing out has a high priority in European policy, as well as in organic agriculture. Our survey aims at providing an overview of the current use of these products in European organic agriculture and the need for alternatives to allow policymakers to develop strategies for a complete phasing out. Due to a lack of centralized databases on pesticide use, our survey combines expert knowledge on permitted and real copper use per crop and country, with statistics on organic area.

Powdery mildew (PM) caused by Podosphaera xanthii is one of the most important courgette diseases with high yield losses and is currently controlled by fungicides and sulphur applications in conventional and organic production. Plant derived elicitors/inducers of resistance are natural compounds that induce resistance to pathogen attack and promote a faster and/or more robust activation of plant defense responses. Giant knotweed (Reynoutria sachalinensis, RS) extract is a known elicitor of plant defenses but its mode of action remains elusive.