Forage Crops 331 



It is first found chiefly upon the leaf stalks, later upon the 

 stems, near the surface of the ground and just below the 

 flower clusters, as elongated sunken spots, which result 

 eventually in the cleath of the whole plant. It frequently 

 causes great loss, and is said, by Bain, to be the most serious 

 plant disease in Tennessee. Alsike clover is nearly immune. 

 Hope lies in the use of resistant varieties. 



Anthracnose {Glceosporium caulivorum Kirch.). — Long, 

 brown to black, sunken spots upon stems and petioles, caus- 

 ing death of the more distal parts, are diagnostic characters 

 of this anthracnose, which was first reported in the United 

 States by Sheldon in 1906, and has since been noted as 

 serious in a number of states. 



Minor rliseases 



Leaf-spot ^-^ {Pseudopeziza trifolii (Biv-Bernh.) Fcl.). — 

 This leaf-spot much like that of alfalfa occasionally causes 

 considerable damage. A Cercospora leaf-spot is also re- 

 corded. Black-mold {Macrosporium sarcinceforme Cav.) is 

 widely distributed as the cause of concentric spots on leaf 

 and petiole. Scab (GibbereUa saubinetii, Fusarium) . — This 

 parasite of cereals is also known to cause depressed, oblong 

 spots upon clover. See wheat. Broom-rape (Orobanche 

 minor L.) is similar to that upon tobacco. See p. 259. Root- 

 rot (Rhizodonia) is sometimes injurious. Dodder. See 

 alfalfa. 



COWPEA 



Wilt ^•^'^ (Fusarium vasinfectum Atk.). — This disease, 

 closeh^ like wilt of cotton, okra, and watermelon, is not com- 

 municable from one of these plants to the other, though it is 

 identical with the wilt of the soy bean. 



It first appears when the plants are about six weeks old. 

 Up to this time they grow well and appear healthy. Scat- 

 tered plants then begin to drop their leaves, the lower ones 

 falling first. Growth is checked, and the stem shows a faint 



