Abstract: New pyridylphosphoric acid derivatives, a process for the manufacture thereof by reaction of pyridinecarboxylic acid esters with salts of phosphoric acid derivatives, and pesticides containing these new pyridylphosphoric acid derivatives as active ingredients. The compounds of the invention have the formula ##STR1## where X denotes hydrogen or halogen, Y denotes oxygen or sulfur, R.sup.1 denotes linear or branched alkyl, alkenyl or alkynyl of a maximum of 6 carbons atoms, or unsubstituted or halogen-substituted phenyl or benzyl, R.sup.2 denotes linear or branched alkyl, unsubstituted phenyl, substituted phenyl, alkyloxy or alkylthio of a maximum of 6 carbon atoms, alkenyloxy or alkenylthio of a maximum of 6 carbon atoms, alkynyloxy or alkynylthio of a maximum of 6 carbon atoms, amino or alkylamino with from 1 to 4 carbon atoms in the alkyl moiety, or dialkylamino with from 1 to 4 carbons atoms per alkyl moiety, and R.sup.3 denotes alkyl of from 1 to 4 carbon atoms.

Abstract: New and valuable salts of phosphonic acids whose cationic components are ammonium radicals, agents for influencing the growth of plants with these salts, and a process for their manufacture.

Abstract: New and valuable 2-chloroethane-phosphonic acid derivatives having a strong biological action, agents for controlling the growth of plants containing these compounds as active ingredients, a process for influencing the growth of plants with these compounds, and a process for their preparation.