Degradation behaviour of potassium K-phosphite in apple trees

Summary in the original language of the document

Although potassium phosphite is not registered for organic fruit production in Europe, it
has long been regarded as a potential alternative to sulphur- and copper-containing
fungicides. In 2005/2006 a field trial was carried out to verify the presence of residues of
phosphoric acid over time in apples after applications of potassium phosphite at different
time-points. No residues were present on fruits if treatments were applied before flowering,
whereas treatments after flowering, in the summer or in autumn resulted in comparable
residue levels irrespective of the period of application. Residues were eveneven found in
leaves and fruits of the following years, 2006 and 2007.