560 



DISEASES OF ECONOMIC PLANTS 



Fig. 155. — Head of rye attacked by an- 

 thracnose. After Manns. 



the Borage family, but has 

 never been found occurring 

 naturally in America. 



Smut ( Urocydis occulta 

 (Wallr.) Reb.). — Unlike 

 most of the cereal smuts, 

 this affects the stems and 

 leaves, not the floral parts. 

 It may be recognized by the 

 usual dusty black spores, 

 which occur especially at 

 the joints. While this dis- 

 ease does not directly at- 

 tack the grain, it does 

 diminish the yield by weak- 

 ening the plant. It has not 

 as yet been seriously de- 

 structive in this country. 



Anthracnose (Colleto- 

 trichum cereale Manns). — 

 A serious disease of cereals 

 and other grasses, chiefly 

 rye, wheat, oats, timothy, 

 blue grass, red top, and or- 

 chard grass, was discovered 

 by Selby and Manns ^ in 

 1908 and described in 1909. 



It seems to be a destruc- 

 tive pest of very general dis- 



1 Selby, A. D., and Manns,' T. 

 F., Ohio Agr. Exp. Sta. Bui. 203, 

 April, 1909. 



