Family Convolvulaceac 179 



stantly spread and increase in the land, as the sweet 

 potato is grown continuously on the same ground. 

 This being the case, we cannot expect healthy plants 

 to thrive or be free from disease on land that is badly 

 infected with disease. Cleanliness is, therefore, the 

 only means of keeping out disease from fields de- 

 voted to sweet potatoes. 



Sprout Treatment. Before being planted, sprouts 

 should be treated, in order to insure the best stand. 

 Not only are untreated sprouts subject to chance con- 

 tamination, but they are also the prey to flea beetles 

 as soon as they are planted. When the sprouts are 

 pulled from the seed bed they should be taken at 

 once to a shaded place and dipped into a Bordeaux 

 mixture, 3-3-50. 



Other Field Control Measures. Growers will do 

 well to make it a point to inspect their fields every 

 week or two and pull out and burn stunted plants 

 which are yellow, sickly looking, and which fail to 

 grow. These should never be left near the seed bed, 

 but should be destroyed so that the disease cannot 

 spread to the healthy plants. Clean cultivation is 

 essential in preventing field diseases with the sweet 

 potato. In cultivation, great care should be taken 

 to prevent injury to the roots, as an injury means 

 a possible opening for disease. 



STORAGE METHODS OF CONTROL 



Before satisfactory conditions can be found for the 

 proper storing of sweet potatoes, there must be a 



