Phosphorous acid (H3PO3) and phosphonic acid are two tautomers whose salts are commonly called phosphites or phosphanates.
Phosphites have two actions: they destroy the mycelium of the mushroom and stimulate the plant's self-defenses (phytoalessin).
Phosphites are molecules that are very active  in plants, as they are easily assimilated by the plant given their water solubility.
The use of phosphites is not allowed in organic agriculture but it is admitted in integrated pest control.
Vassanelli Lab is able to analyse residues of Fosetyl-Aluminium and its metabolites or degradation products with the CVUA EU RL-SRM quppe method on all fruit and vegetables with LOQ of 0.01 mg/kg.
The analysis is Accredia accredited as required by point 8.1 of RT-16 Rev.5
With regard to organic fruit and vegetable products, the detection of phosphonic acid only >0.01 mg/kg, in the absence of simultaneous detection of ethylphosphonic acid, is not a sufficient condition for excluding the use of technical means that are not allowed or those that are allowed but not in conformity due to the undeclared presence of ethylphosphonic acid and / or phosphite-based products, and must lead to further in-depth analysis aimed at assessing the potential origins of the positivity detected. As a research tool, it is advisable to acquire a list of the technical means and production batches used by the farmer for fertilisation and protection in the current year, and in the case of multi-year crops also over the previous years, and pass this information to the authorities responsible for monitoring for subsequent checks.

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