Plate \^II. — Sweet potato diseases, o and 6, Leaf of sweet potato 

 plant, showing the presence of » number of circular leaf-blight spots, 

 c and d, Leaf of a sweet potato plant, showing white spots caus^ by 

 the leaf-spot fungus, e and /, Leaf of a sweet potato plant, showing 

 the white-rust fungus, g. A sweet potato showing the characteristic 

 appearance of dry-rot. 



