PREVENTATIVE AND CURATIVE APPLICATIONS OF VERTICILLIUM-LECANII FOR BIOLOGICAL-CONTROL OF CUCUMBER POWDERY MILDEW

The effect of timing of the application of the mycoparasite, Verticill ium lecanii, on cucumber powdery mildew, Sphaerotheca fuliginea, was s tudied in a rooted cucumber leaf bioassay. The mycoparasite teas appli ed at different times before and after mildew inoculation. At near-to- maximum humidity (> 95% relative humidity), early preventative (9 and 5 days before mildew inoculation) and early curative control treatment s (2 days after mildew inoculation) gave considerable reduction in mil dewed leaf areas, while late curative treatments resulted in greater m ildewed leaf area but ultimately a reduced amount of healthy mildewed leaf ni ea (< 20%). Appropriate timing of biocontrol treatment applica tion of V. lecanii is important to achieve good control.