82 DISEASE AND ITS PREVENTION 



tubers. When the tubers are cut, the disease germs may 

 enter easily. 



Gophers are another pest to the potato grower. They 

 will do a great amount of damage in one night, by cutting 

 the vines. If the vines grow again the tubers that appear 

 will be prongy, and sometimes will cause small tubers to 

 grow on the vine, between the leaf and the stalk. 



In conclusion of this chapter on "Disease and Its Pre- 

 vention," I would emphasize the following points : 



1st. Above all things, never plant diseased potatoes. 



2nd. The more thorough the cultivation and the richer 

 the soil, the less liable are the tubers to disease. 



3rd. Cull potatoes are responsible to a great extent for 

 the increase of disease and should always be removed from 

 the fields at harvest time. 



4th. In spraying it is well to use a high-pressure spray 

 and a fine nozzle. 



5th. Never leave volunteer potatoes in the field from 

 year to year, as it is these small diseased tubers that cause 

 the spreading of disease. 



