20th Meeting of the EPPO Expert Working Group on Resistance to Plant Protection Products

Oeiras (PT), 2026-10-01/03

The EPPO Expert Working Group (EWG) on Resistance to Plant Protection Products (PPP) considers all aspects of data requirements for efficacy evaluation of plant protection products in relation to resistance issues to facilitate communication and regulatory data exchange on PPPs between authorities in different countries and between agrochemical companies (applicants) and authorities. One of its current main tasks is to develop and maintain the EPPO Database on Resistance Cases. A list of members and the Terms of Reference of the EWG are available on the EPPO website.

The 20th meeting of the EPPO EWG on Resistance to PPPs took place in Oeiras, Portugal, from October 1 to 3, 2025. Many thanks are due to the Instituto Nacional de Investigação Agrária e Veterinária (INIAV) for kindly hosting the meeting. The meeting was attended by the EPPO Scientific Officers Mr Lucchesi (Chair) and Mr Martínez Pérez,11 EWG members from ten EPPO countries, two observers, one CropLife Europe representative and the European Herbicide Resistance Action Committee representative.

Photo of the EPPO EWG on Resistance to PPPs, including a technical visit.

The EWG continued working on the EPPO Database on Resistance Cases. In addition to the 992 resistance cases already validated in previous EWG meetings (and visible in the Database for all users), this year the EWG considered more than 250 new (or updated) cases of which, more than 200 were validated. The cases validated at the meeting will soon be visible for all users of the Database. The cases which could not be validated at the meeting will need further work or consideration by the countries that proposed them.

Experts presented an update on the current and new resistance cases and management strategies in their countries. Presentations were made by experts from Austria, Denmark, France, Germany, Greece, Ireland, Italy, the Netherlands, Portugal, Sweden, Switzerland and the United Kingdom. The Resistance Action Committees (RACs) representatives (with FRAC and IRAC participating remotely) informed the EWG about new developments and recent activities. The EWG also discussed how to move forward with the planned new draft Standard on generating sensitivity data for PPP resistance monitoring.

A technical visit was provided by Adega Casal da Manteiga. The winery is part of a national heritage and agricultural restoration project dedicated to the production of Carcavelos wine with native grape varieties.

The EPPO Expert Working Group on Resistance to PPP will next meet on 2026-10-06/08 in Paris at the EPPO Headquarters.