Phosphonic Acid/Fosetyl-Al

Phosphonic Acid

Phosphonates are considered multiple-source substances because of their wide range of applications and widespread occurrence. They are found in pesticides and fertilizers, and they can also be found in natural sources. Until now, phosphonates have been summarized as residues of fosetyl (specifically, the sum of fosetyl and phosphonic acid and their salts, expressed as Al-fosetyl).

In particular, phosphonic acid poses challenges for organic farming as an unspecific residue because such findings raise the question of unauthorized use of plant protection products containing phosphonic acid.

In October 2024, the European Union changed the residue definition to "phosphonic acid and its salts expressed as phosphonic acid" to cover all entry routes of phosphonates via common maximum levels. However, it should be noted that this definition no longer includes fosetyl. The standard value of 0.01 mg/kg, previously used for product-active substance combinations for which no specific maximum levels were set, is no longer used. Accordingly, residues of fosetyl will no longer appear in test reports. These changes have been in effect since April 29, 2025.

This analysis is still part of our standard portfolio, of course. Please contact us if you have any questions.