386 



DISEASES OF ECONOMIC PLANTS 



most other rusts ; indeed other forms of spores are almost 

 entirely absent in most parts of the country, throwing the 

 burden of perpetuation of the species entirely upon the uredo 

 mycehum and its spores. This stage is known to be peren- 

 nial as far north as Washington, DC, and Lincoln, Neb. 

 The rust is very destructive, and seems to be limited to 



this one host. 



Smut. See timothy. 

 Anthracnose. See 

 rye. 



CLOVER 



Black mold (Phyl- 

 lachora Trifolii 

 (Pers.) Fckl.).— 

 Common red clover, 

 crimson clover, white 

 clover, alsike clover, 

 and several other related plants are affected by this mold. 

 The chief symptoms are pale spots upon the upper sides 

 of the leaves accompanied by black dots on the lower sides. 

 These spots at first glance so strongly resemble the sori of 

 the rusts as to lead the disease to be mistaken for a rust by 

 the casual observer. 



Though the disease is often of considerable damage, no 

 treatment is known. 



Sclerotiniose, wilt (Sclerotinia Trifoliorwn Eriks.). — This 

 wilt is possibly identical with the wilt of alfalfa. In any 

 event it resembles it very closely. It was first noted 

 in America, in Delaware, by Chester in 1889, later in New 

 Jersey by Halsted. 



Fig. 165. — Clover leaf showing spota of black mold. 

 Original. 



