has role fungicide phosphonic acids phosphorus oxoacid phosphonate(1-) phosphorous acid phosphonic acid [PHO(OH)2] H2PHO3 A phosphorus oxoacid that consists of a single pentavalent phosphorus covalently bound via single bonds to a single hydrogen and two hydroxy groups and via a double bond to an oxygen. The parent of the class of phosphonic acids. (HO)2HPO HPO(OH)2 Phosphonate phosphonic acid Phosphite CHEBI:44976 chebi_ontology H3PO3 Phosphonic acid Phosphonsaeure CHEBI:26067