Microscopic Views of Basil Downy Mildew Updated June 2020. (Originally prepared for Vegetable MD Online.) Photographs of the basil downy mildew pathogen, Peronospora belbaharii, at various magnifications. P. belbaharii observed with a dissecting microscope. Images courtesy of Robert L. Wick, Stockbridge School of Agriculture, University of Massachusetts. P. belbaharii observed with a dissecting microscope. Images courtesy of Robert L. Wick, Stockbridge School of Agriculture, University of Massachusetts. P. belbaharii observed with a compound microscope. Images courtesy of Robert L. Wick, Stockbridge School of Agriculture, University of Massachusetts. P. belbaharii observed with a compound microscope. Images courtesy of Robert L. Wick, Stockbridge School of Agriculture, University of Massachusetts. A differential interference image of P. belbaharii. Image courtesy of Robert Belas, Department of Marine Biotechnology, University of Maryland Baltimore County, and Institute of Marine and Environmental Technology. A differential interference image of P. belbaharii. Image courtesy of Robert Belas, Department of Marine Biotechnology, University of Maryland Baltimore County, and Institute of Marine and Environmental Technology. A false-color image of P. belbaharii taken with a 25x objective. Image courtesy of Robert Belas, Department of Marine Biotechnology, University of Maryland Baltimore County, and Institute of Marine and Environmental Technology.