Cucurbit powdery mildew, resistance

It is essential to control mildew strains resistant to SBI fungicides such as Fenaiimol (3), and Table II depicts the dramatic control of both Fenarimol-sensitive and resistant cucurbit powdery mildew after treatment with LY186054. In this, as well as other related studies, there was no indication of cross-resistance of this quinoline with additional commercial fungicides. 

Qol resistance was first reported in wheat powdery mildew in northern Germany in 1998 (5). In Japan, control failure by these fungicides has been reported in five diseases so far, i.e. cucurbit powdery mildew, cucumber downy mildew, eggplant leaf mold (4), cucumber Corynespora leaf spot (5), and wheat powdery mildew. In most cases, the level of Qol resistance was high enough to cause complete loss of fiingicide efficacy at the fiingicide concentraticai recommended for practical use. 

As a result of this search for novel fungicides, a series of analogous phenoxyquinolines has been developed which controls sensitive and resistant strains of powdery mildew in cereals, cucurbits and grapes. The discovery and structure-activity relationships as well as the greenhouse and field efficacy of selected compounds are detailed in this report. 

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