214 Diseases of Economic Plants 



PEANUT 



Leaf-spot (Cercospora personata (B. & C.) Ell.). — This 

 leaf-spot is circular in outline, indefinitely bordered, black 

 to brown in the center and grading to green on its outer 

 edge. The lower leaves are first affected and suffer most; 

 later the disease spreads to the upper leaves. The leaves 







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Fig. 116. — Peanut leaf-spot. After Wolf. 



begin to fall soon after they spot, and in many cases the 

 death of the plant results. It is often a pest. The causal 

 fungus was first collected in Carolina and Alabama by 

 Ravenel. 



Southern-blight {Sclerotium rolfdi) does some damage. 

 (See pp. 23, 215.) The true rust (Uredo arachidis Lag.) is 

 injurious in the sub-tropics. Red-rot of the pods, charac- 

 terized by brown discoloration and tlie presence of red 

 perithecia (Neocostnospora) is of slight importance. 



