Potatoes 213 



potato storage houses at very little expense. These houses 

 will usually need to be ceiled on the inside. For this purpose 

 two-inch by four-inch scantlings should be set against the wall 

 and covered with building paper and then a layer of matched 

 lumber. The windows and doors should be made tight and 

 ventilators put in where needed. 



122. Pests of the sweet potato. Few insects are trouble- 

 some to sweet potatoes. 



The root-borer is sometimes destructive in Texas and Louisi- 

 ana. This insect bores into the roots and injures them. The 

 treatment is to avoid storing or bedding infested roots. 



Black rot is the most serious disease of the crop. Black 

 spots appear on affected roots which soon rot. To combat 

 this disease care should be taken not to bed infested roots and 

 not to plant slips that show dark spots on their stems. As 

 stated previously roots from plants propagated by vine cut- 

 tings are likely to be free from the rot and are the best kind to 

 use for bedding. The organism of the disease is carried over 

 in the soil and for this reason it is well to plant some crop other 

 than sweet potatoes for a few years on land from which a 

 badly infested crop has been harvested. Several other rots 

 attack sweet potatoes, but the remedies are the same as for 

 black-rot. Proper storage aids in combating the rots. 



QUESTIONS 



1. Compare the average yield and possible yield of white potatoes 

 in the United States. 



2. What kind of soil is best for white potatoes ? 



3. What size seed pieces of white potatoes seem to give best re- 

 sults? 



4. Why is rather deep planting usually advised for white potatoes ? 



5. Give the life history of the Colorado potato-beetle and state 

 the method of control for this pest. 



6. How are early blight, late blight, and scab combated ? 



7. What kind of soil is best for sweet potatoes ? 



8. What general formula is employed in fertilizing land for sweet 

 potatoes ? 



