LUTHER BURBANK 



specialized breeding in which selection has been 

 made generation after generation with reference 

 to the quality of the seed has been the gradual loss 

 on the part of many varieties of the cereals of the 

 power to ward off the attacks of a fungus pest 

 that finds their stalks its favorite feeding ground. 



This pest is known to the farmer as "rust," 

 because in many forms it gives to the stalks of the 

 plant, once it is fairly lodged and under develop- 

 ment, a blotched, reddish brown appearance sug- 

 gestive of the scales of rust that appear on a 

 metallic surface. 



To the botanist the fungus is known as a mem- 

 ber of the tribe of so-called Euridineial or Cup 

 Fungi. The most familiar species is known as 

 Puccinia graminis. 



The precise history of this parasite has been 

 very difficult to trace. It is known, however, that 

 the germinal matter lodges on the stalks of the 

 grain in the form of minute spores, and that these 

 send little rootlets into the substance of the grain 

 cell and sap its vitality. 



It is further known that at one stage of their 

 career some varieties of rust plant lodge on the 

 leaves of the common barberry and there develop 

 another type of spores. This fact has made the 

 botanist look askance at the barberry, not unnat- 

 urally. Yet it is known that rust attacks the wheat 



[48] 



