-ARID AGRICULTURE. 275 



Some of these men believe the diseases we have 

 that seem common to other places, are new and 

 typical of our own agriculture. As an example, 

 it has been stated that the potato scab of the 

 West, which scientists and writers have consid- 

 ered identical with that of the East, is not the 

 same disease, but is produced by an entirely dif- 

 ferent fungus. Our potato blight is a Western 

 potato blight, probably due to the same fungus 

 which produces dry rot, and not to the fungus 

 which produces the late blight of the East. 



These considerations and the new discoveries 

 indicate that, even with our plant diseases, we 

 must unlearn the old and learn the new. We 

 must build up our own knowledge of agriculture 

 and take nothing for granted because it appears 

 to be so from what we have known in other coun- 

 tries. 



There are diseases of grain, such as rusts, 

 for which there is no effective treatment. Rusts 

 do not affect grains to any extent in the dry re 

 gion, and careful irrigation may prevent dam- 

 age from them. With many diseases the solu- 

 tion will be the breeding of disease-resistant 

 strains. The cantaloupe blight has been effectu- 

 ally controlled by breeding disease-resistant 

 -trains of seed. We are now working to control 

 the leaf-spot disease of alfalfa. 



POTATO There is one great, ever-present, and destruc- 



r * ve disease of potatoes which causes incalculable 



