PLATE B 



Young maize plants, showing the effects of later attack of the downy mildew on a 

 large, late-maturing variety, Guam White Dent. 



The two plants at the right are diseased; the one at the left is healthy. Notice the 

 characteristic markings on the larger diseased plant — the whitish yellow sheath of the 

 lowest affected leaf, the short narrow stripes at the base of the next leaf, and on the 

 later leaves the whitening of the entire breadth at the base and the extension of broad 

 stripes increasingly far into the normal green of each successive leaf tip. The leaves 

 are nearly as broad and flexible as in normal plants, and their growth is little checked, 

 if at all. The plants are 31 days old and developed the symptoms of the disease 25 

 days after emerging from the soil. One-seventh natural size. 



