396 DISEASES OF ECONOMIC PLANTS 



ORCHARD GRASS 



Scolecotrichose (Scolecotrichum graminis, Fckl.)- — In 

 times of severe drought elongated dead spots may 

 appear upon orchard grass, most conspicuous upon the 

 lower outer leaves. Following these comes the death of 

 the leaf, sometimes starting at the leaf tips and reaching 

 to the base. In conditions favorable to the disease whole 

 plants are involved. The spots, before they become con- 

 fluent, are of quite characteristic appearance: large, dark 

 brown to purphsh brown. When old, they usually show 

 at their centers spots of gray or white, and these spots 

 may be marked with very small black pycnidia arranged 

 in rows lengthwise of the leaf. 



Black stem rust (Puccinia graminis Pers.). — This rust is 

 identical with the oat rust caused by Puccinia graminis, and 

 it may be conveyed from either of these hosts to the other. 



Rust {Puccinia Rhamni (Pers.). Wett.). — It is probable 

 that orchard grass can act as host for this species, which 

 has been described under oats. 



Anthracnose. See rye. 



QUACK GRASS 



Smut. See timothy. 



Smut, urocystose ( Urocystis Agropyri (Preuss.) Schroet.). 

 — This smut resembles the above closely in the general 

 appearance of its sori, though microscopically its charac- 

 ters are quite different ; its spores show a more reddish hue. 



RED TOP 



Black stem rust (Puccinia graminis, Pers.). — The rust 

 is identical with that upon wheat and 03,ts, though in- 

 fection does not readily occur from one host to the other. 



