The present invention relates to novel pyridazine derivatives of formula (I) as active ingredients which have microbiocidal activity, in particular fungicidal activity: wherein R
1
is methyl, ethyl or isopropyl; R
2
is chloro, fluoro, hydroxy or C
1
-C
2
alkoxy; R
3
is H, chloro, fluoro, methoxy or C
1
-C
3
alkyl; R
4
is chloro, fluoro or bromo; and R
3
is H, fluoro or methoxy; or an agrochemically usable salt form thereof; with the proviso that when R
1
is methyl, R
2
is chloro and R
3
is H, then R
4
or R
5
is different from fluoro.
本发明涉及式(I)的新型
吡嗪衍
生物作为活性成分,其具有微
生物杀菌活性,特别是杀真菌活性:其中R1为甲基,乙基或异丙基;R2为
氯,
氟,羟基或C1-C2烷氧基;R3为H,
氯,
氟,甲氧基或C1-C3烷基;R4为
氯,
氟或
溴;R3为H,
氟或甲氧基;或其农药可用盐形式;但当R1为甲基,R2为
氯,R3为H时,R4或R5与
氟不同。