LUTHER BURBANK 



in Australia where the barberry does not grow; 

 and experiments have also shown that the rust 

 may be propagated for an Indefinite period with- 

 out passing through the phase of development in 

 which the barberry is its best. 



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 dif- 

 ferent lines. There could be no hope of eradicat- 

 ing 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 by 

 saving for seeding purposes the grain of plants 

 that proved individually resistant to the rust, have 

 long been carried out more or less systematically. 



[50] 



