18 Potato Disease and Allied Diseases [CH. 
examination under the microscope shows that the 
white threads consist of a number of branched hyphae 
carrying lemon-shaped bodies (Fig. 9A). This is the 
Fig. 8. A potato leaf showing the patches which indicate the 
presence of the potato disease fungus. 
fruiting stage of the fungus which causes the potato 
disease. 
These small bodies are the spores or conidia of the 
fungus. Each conidium is formed by the swelling of 
