PLATE i6' 



A. — Portion of a field of Moro White maize, showing heavy loss from the downy 

 mildew. At the left, near the scale, is seen the only healthy plant that remains in 

 this part of the field. Near it are several pale, stunted plants which are already 

 withering, while in the background may be seen other plants less seriously attacked. 



B. — View near the edge of a field of Guam White Dent maize, showing the ravages 

 of the downy mildew. 'The tall, dark-leaved plant near the scale and two others a 

 little farther back are the only healthy plants seen. Notice the stimted, withering 

 specimens in the foreground, and at the right the seriously affected individual with 

 stiffly ascending, striped leaves. 



' On the scale which appears in this and the following photographs each black division equals 5 cm. 

 Photsgraphs by W. H. Weston. 



