390 DISEASES OF ECONOMIC PLANTS 



the United States by Sheldon in 1906, and has since been 

 noted as serious in a niunber of states. 



Leaf spot {Psevdopeziza Trifolii (Biv. Bernh.) Fckl.)- — 

 Perhaps identical with the similar disease of alfalfa, this 

 occasionally causes considerably damage. 



Macrosporiose {Macrosporium sarcinicBforme Cav.). — 

 This widely distributed black mold is a common cause of 

 leaf spots. 



Scab (Gibberella Saubinetii (Mont.) Sacc). — This 

 parasite of grains is also known to cause depressed oblong 

 spots upon clover. See wheat. 



Broom rape (Orobanche minor. L.). — The parasite which 

 causes this disease is very similar to that upon tobacco. 

 See p. 307. Orobanche has also been noted upon pelar- 

 gonium, tomato, coleus, and several other plants. 



Dodder. See alfalfa. 



CRAB GRASS 



Piriculariose (Piricularia Oryzce Cav.). — This is proba- 

 bly identical with rice blast. See p. 352. 



COWPEA 



Wilt,fusariose {Fusarium vasinfedum Atk.) — This disease 

 is closely like fusariose of cotton, okra, and watermelon, 

 though the disease is not conmiunicable from one of these 

 plants to the other. 



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

 Up to this time they will grow well and appear healthy. 

 Scattered plants then begin to drop their leaves, the lower 

 ones falling first. Growth is checked, and the stem shows 



> Orton, W. A., U.S. Dept. Agr. Bur. Plant Indus. Bui. 17, April, 1902. 



