340 



Diseases of Economic Plants 



PASPALUM 



Ergot '^^^ {Claviceps paspali S. & H. and C. rolfsii S. & H.). 

 — The ergots displacing the grain are somewhat smaller than 

 a pea, irregularly globular in outline, and pale yellow in 



color. Stock poisoning 



from pasturing on grass 

 bearing these ergots is com- 

 mon in the South. Mow- 

 ing the green heads before 

 the ergot develops will les- 

 sen the danger. 



QUACKGRASS (Agropyron) 

 Smut ( Urocystis agropyri 

 (Preuss.) Schroet and Usti- 

 lago) . — These smuts re- 

 semble each other in the 

 general appearance of the 

 sori, though microscopi- 

 cally the characters are 

 quite different. 



REDTOP {Agrostis) 



Black-stem- rust {Puccinia graminis agrostis Erks.). — 

 The rust is identical with that upon wheat and oats, though 

 infection does not readily pass from one host to the other. 



Smut (Ustilago striceformis (West.) Niessl). — This is 

 the smut described under timothy. It has been known 

 to affect 30 per cent of the plants, and to reduce the seed 

 yield from 300 hundredweight to 70 hundredweight. 



Anthracnose. See rye. 



Fig. 181. — Ergot on Paspalum. 

 After Beal. 



TALL OATGRASS 



Smut {Ustilago perefinans Rostr.). — This smut closely 

 resembles that of oats, though the flower parts are not so 

 completely destroyed as in oat smut. The disease is peren- 



