PLATE 4 
Helminthosporium avenae 
A.—Portion of oat plant showing a number of discolored areas on upper leaves due 
to attack by H. avenae. X^- 
Ba- 1 .—Spores of H. avenae from diseased oat leaf showing variation in size, shape, 
and septation. X500. 
Ca-b.—Spores from diseased oat leaf, germinating in water showing production 
of germ tubes from end and middle segments. X500. 
Da-g.—Conidiophores emerging singly or in groups of 2 or 3, from stomata or between 
contiguous epidermal cells. Dc and De exhibit type of branching occurring oc¬ 
casionally in this species. X500. 
