Disease: Downy mildewPathogen: Peronospora parasiticaHosts: cabbage and other crucifers (brassicas)
This delicate tree-like structure is one example of the elegance of the microscopic world. It is the asexual reproductive structure of the downy mildew pathogen, Peronospora parasitica. The sporangia are blown to new host plants for infection. Relative humidity and leaf moisture are important factors in the development of downy mildews. Control of these factors is important to controlling these diseases. (Courtesy of G. A. Payne)