Forage Crops 337 



Powdery-mildew (Erijsiphe polijgoni DC). — The white 

 spots of this mildew are strictly circular when j^oung, but 

 as they enlarge they coalesce and cover the whole upper 

 surface of the leaves with a white powder. 



The disease is very widespread, but even in the worst 

 seasons does not do much injury. 



Angular leaf-spot (Cercospora cruenta Sacc). — ^ The an- 

 gular leaf-spots of this disease are a familiar sight in most 

 cowpea fields. They are of various colors above, chiefly 

 reddish, and are gray to purplish or slate-colored below. 

 The damage is rarely very great. In some instances the at- 

 tack may proceed to the stems, where, especially at the base, 

 it may cause cracking and result in such lowering of the vigor 

 of the plant as to cause shedding of leaves and failure to 

 properly fill the pods. The loss of leaves is of course serious 

 to the hay value of the crop. 



Root-rot (Thielavia); a Phyllosticta leaf-spot and a Sep- 

 toria leaf-spot also occur. Streak. See sweet pea. 



JAPAN CLOVER (Lespedeza) 



Powdery-mildew {Microsphcem diffusa C. & Pk.). — 

 The usual characters of the powdery-mildews distinguish 

 this disease sufficiently. The injury to this valuable southern 

 forage plant, while considerable, is never sufficient to call 

 for treatment. 



SOY BEAN (Soja) 



Bacterial blight •'32-534 (Pseudnmonas glycineum Coerper) . — 

 Small, angular spots, 1-2 mm. in diameter, at first water 

 soaked, translucent, later yellow or brown and eventually 

 brown or purplish black, occur on the leaves and pods 

 accompanied by a bacterial exudate. 



The disease has been reported from Nebraska, Connecti- 

 cut, Wisconsin, and North Carolina. 



It is thought to be seed-borne. 



Wilt. See cowpea. 



