FUNGI, THE RUST FUNGI 



317 



investigations undoubtedly being stimulated by those of a 

 renowned French botanist, Tulasne, who had previously shown 

 the connection of the uredo and teleuto stages. These studies 

 have since been verified, both in Europe and in the United States, 

 in regions where the barberry grows. 



469. Other grain rusts. There are a number of other rusts 

 which attack wheat and other cereals. One of the most destruc- 

 tive of these in this country is Puccinia rubigo-vera. In some 

 regions in the United States this rust is more abundant and does 

 more injury to the wheat than the Puccinia graminis. 



Fig. 277. 



Cedar apples, the winter condition. Abnormal growth of the cedar caused by a fungus 

 (Gymnosporangium macropus). The masses of spores ready to ooze out are in the little pits 

 with the conical elevations. 



470. Prevention of wheat rust. No practical method has 

 been found of successfully combating the wheat rust. Formerly 

 laws were enacted in England and Massachusetts requiring the 

 destruction of the barberry, but this did not materially lessen the 

 disease. The selection of resistant varieties gives promise of solv- 

 ing the problem. The " macaroni" wheats are more resistant 

 than many other varieties, and experiments in crossing are being 

 made with the hope of obtaining still more resistant strains (see 

 paragraph 679). 



