(1.Institute of Plant Protection，Heilongjiang Academy of Agricultural Sciences，Harbin,Heilongjiang 150086;2.Branch of Horticultural，Heilongjiang Academy of Agricultural Sciences，Harbin，Heilongjiang 150069)
The experimental material of this trial was ４％ tetraconazole aqueous emulsion，the experimental comparison were Thiphanate-mythy1 and water.４％ tetraconazole aqueous emulsion was used in the field efficacy trials to control melon powdery mildew.The results showed that control effect of ４％ tetraconazole aqueous emulsion was better to melon powdery mildew，after spraying 2 times，the control efficiency of ４％ tetraconazole aqueous emulsion to melon powdery mildew was over 80%，and it was safe to melon leaves and fruits in all experiments.The control effect of ４％ tetraconazole aqueous emulsion was significantly higher than CK，the control effects were higher to melon powdery mildew，especially ４％ tetraconazole aqueous emulsion at 800× and 600×,control efficacy were 74.94% and 81.63%,respectively.