PYRIDAZINON DERIVATIVES, THEIR PREPARATION AND THEIR USE IN AGRICULTURAL COMPOSITION AND THE TREATMENT OF SEED AND PLANTS

摘要

Compounds of formula (I): < IMG > (I) ¢in which: A represents a group of formula -CH=CH- or -CH2-CH2-, R1 represents a halogen atom; R2 represents a hydrogen atom, a hydroxy group, a halogen atom, an alkyl group or an alkoxy group; R3 represents a hydrogen atom or a halogen atom; and Y represents a hydroxy group, a halogen atom, an alkylamino group, a dialkylamino group, an a1kenylamino group, a dialkenylamino group, an anilino group if (n which the aromatic ring is unsubstituted or has one or two halogen and/or alkyl substituents), a cycloalkylamino group, a 1-pyrrolidinyl group, a piperidino group, a morpholino group, a group of formula < IMG > (in which R4 represents an alkyl group or a phenyl group) or a group of formula < IMG > (in which A, R1, R2 and R3 are as defined above)! are useful agricultural fungicides having greater systemic activity and chemical stability than known compounds of similiar structure. They may be applied as such or in a conventional preparation to seeds and growing plants. They may be prepared by reacting a 6-(substituted phenyl)-3(2H)-pyridazinone with formaldehyde and optionally with a halogenating agent, an appropriate amine or piperazine.