NEW PYRIDAZINE COMPOSITIONS, PRODUCTION PROCESS THEREOF AND FUNGICIDES AND ALGICIDES CONTAINING THEM

Pyridazine derivatives having general formula (I), wherein R1? is a hydrogen atom or a saturated or unsaturated alkyl rest having between 1 and 4 atoms of carbon, R2? is a hydrogen atom or a straight or branched, saturated or unsaturated alkyl rest having between 1 and 10 atoms of carbon, a cycloalkyl rest, an alkoxyalkyl rest, a hydroxyalkyl rest, or a phenyl rest optionally substituted once or a plurality of times with halogen atoms or R1? and R2? form together with the N atom a closed cycle having between 5 and 7 members and which may have nitrogen or oxygen as additional heteroatom and may optionally be substituted with alkyl, hydroxyalkyl, hydroxyl, phenylalkyl or pyridyl residues, R3? is a phenyl residue or a tertiary butyl residue optionally substituted once or a plurality of times with halogen atoms in position 3, 4, or 5, or optionally substituted once or a plurality of times by branched or straight chain alkyl or alkoxy groups having between 1 and 4 atoms oc carbon, R4? is a hydrogen atom or a straight or branched chain alkyl residue having between 1 and 4 atoms of carbon, R5? is a hydrogen atom, a straight or branched, saturated or unsaturated alkyl or oxoalkyl residue having between 1 and 20 atoms of carbon, optionally substituted with halogen, nitrile, hydroxyl, alkoxyl, phenyl, halogenphenyl or optionally with halogenated phenoxyl residues or a cycloalkyl residue, and A?- is an anion physiologically acceptable by plants except methyliodides of 6-methylamino-3-phenylpyridazine and of 6-dimethylamino-3-phenylpyridazine and of 6-amino-3-phenylpyridazine. The invention also relates to their production process, fungicides and algicides containing said derivatives, and method for their production and utilization.