Cereals 317 



occurring in the fields in spots. They are known in many 

 countries on wheat, oats, barley, rye, and rice, and are very 

 destructive in Europe and Australia. The diseases in their va- 

 rious forms have many names, among them Take-all, White- 

 heads, Pietin. Any one of several fungi may cause foot-rot, 

 especially when the wheat plant is weakened by adverse en- 

 vironmental conditions. A foot-rot of wheat due to unknown 

 cause was reported in Oregon in 1902, and one due to Hel- 

 minthosporium in Illinois and Indiana in 1919. Burning of 

 the stubble and crop rotation, accompanied by good drain- 

 age, are reconmiended. 



Anthracnose {Colletotrichum cereale Manns). — This an- 

 thracnose seems to prevail on wheat as extensively as upon 



Fig. 165. — Normal wheat kernels and shriveled ker- 

 nels due to anthracnose. After Manns. 



rye. The head is not destroyed, as in the case of rye, but 

 general weakness of the plant and light, shriveled grain 

 follows the attack. 



Powdery-mildew ^^ (Enj.^iphe (jraminis DC). — The usual 

 characters of the powdery-mildews are exhibited; a whitish, 

 flour-like coating in irregular, circular spots upon the leaves 

 and other plant parts. This mildew, together with the 

 mildew of oats, rye, and barley, bears the same specific 

 name, but upon each of these crops the form is so special- 

 ized as not to transfer readily, if at all, to the other crop 

 plant. Thus from the farmer's viewpoint there are prac- 



