两种候选甲氧基丙烯酸酯类杀菌剂对黄瓜霜霉病的作用方式

Mode of action of two candidate strobilurin fungicides against cucumber downy mildew

20%唑胺菌酯EC、20%SYP-3998 SC是甲氧基丙烯酸酯类候选杀菌剂,为探索两药剂对黄瓜霜霉病的作用方式,采用盆栽植株喷雾-叶碟法、叶碟喷雾法、盆栽植株喷雾-叶碟法分别测定两药剂对黄瓜霜霉病的保护、治疗及持效期,并采用离体叶片法、叶碟法测定二者对黄瓜霜霉病的铲除作用。结果表明:20%唑胺菌酯EC和20%SYP-3998 SC具有良好的保护、治疗及铲除作用。两药剂的铲除作用表现在能抑制黄瓜霜霉病菌病斑扩展、孢子囊产生及孢子囊再侵染,与孢子囊混合接种能显著降低孢子囊的致病性。此外,20%唑胺菌酯EC和20%SYP-3998 SC具有7～10天的持效期;20%唑胺菌酯EC预防、治疗、铲除效果及持效性均优于20%SYP-3998 SC及对照药剂25%嘧菌酯SC。

Pyrametostrobin 20 EC and SYP-3998 20 SC were two strobilurin candidate fungicides. Preventive, curative and duration of control of two fungicides against cucumber downy mildew were deter- mined by potted plant spray-leaf disc test, leaf disc spray test, and potted plant spray-leaf disc test, and eradicative action of them against cucumber downy mildew were determined by detached leaves test and leaf disc test. The results showed that, pyrametostrobin 20 EC and SYP-3998 20 SC has good preventive, curative and eradicative activity against cucumber downy mildew. The eradicative action of the two candidate fungicides was reflected by their strong inhibition of the lesion extension, production of sporangia, and reinfection of sporangia, and by obvious decreasing pathogenicity of sporangia mixed with the two candidate fungicides. Moreover, pyrametostrobin 20 EC and SYP-3998 20 SC can provide the effective control of cucumber downy mildew 7 - 10 days after foliages spray. The preventive, curative and eradica- tive activity of pyrametostrobin 20 EC is higher than that of SYP-3998 20 SC and azoxystrobin 25 SC, the same with duration of control.