GRASSES OF IOWA. 



251 



Fig. 121. Bunt of wheat, Tilletia foetens, after Bessey. 



a whorl of blender bodies — the primary sporidi a. These spo- 

 ridia produce short tubes which join them to each other. The 

 infection may result from the slender threads produced by the 

 primary sporidia, or from the secondary sporidia, which also 

 produce slend-.r threads. These germ tubes can enter the 

 plant only by way of the delicate tissues of the seedling. 



Damage. — It is difficult to estimate the amount of damage. 

 The percentage in Iowa is usually very small, but in Wisconsin 

 I have seen whole fields destroyed, and Arthur* likewise gives 

 an illustration where one-half of the crop was lost. 



♦Bull. Ind. Agrl. Exp. Sta. 28. 

 1. c. Farmers' Bull. 75: 6. 



