346 LUTHER BURBANK 



botanist look askance at the barberry, not unnat- 

 urally. Yet it is known that rust attacks the 

 wheat in Australia where the barberry does not 

 grow; and experiments have also shown that the 

 rust may be propagated for an indefinite period 

 without passing through the phase of develop- 

 ment in which the barberry is its host. 



So the elimination of the barberry does not 

 constitute the important agency in fighting the 

 rust that the botanist once hoped it might. 



Nor has any other agency been suggested that 

 will combat the pest. Once its spores have found 

 lodgment, it is obvious that there could be no 

 means of spraying or otherwise giving treatment 

 for their destruction or removal that could be 

 applied to a host plant that is grown not individ- 

 ually or in small clumps, like orchard fruits or 

 garden vegetables, but in fields that aggregate 

 millions of acres. 



So it has long been recognized that the battle 

 with the rust plant must be fought out along 

 different lines. There could be no hope of eradi- 

 cating the pest except by making the grain plant 

 itself resistant to the attacks of the enemy. 



DESTRUCTION WROUGHT BY THE RUST 



Experiments in selective breeding, through 

 which new races of wheat have been developed 



