214 ELEMENTS OF AGRICULTURE 



The fertilizing constituents of cottonseed meal and 

 its value per ton as a fertilizer are as follows: 



Lbs. in 



one ton Value 



Nitrogen 135.8 $27 16 



Phosphoric acid 57.6 2 88 



Potash . . . 17.4 87 



$30 91 



202. Fungous Diseases and Insects Affecting Cotton. 

 Cotton is, for the most part, a robust plant; yet, where 

 it is continuously cultivated on the same soil it becomes 

 subject to certain parasitic and fungous diseases. These 

 diseases, when present in a field, develop very rapidly, 

 and the curative measures resorted to are not very effec- 

 tive. When cotton is grown in rotation with corn and 

 some legume, which occupy the soil for one or two seasons 

 and bui'd up the organic matter and nitrogen content 

 of the soil, very little trouble is experienced with para- 

 sitic or fungous diseases. 



The two insects most troublesome in the cotton fields 

 are the Mexican boll- weevil and the cotton-boll worm. 

 Both of these can be retarded to some extent by early 

 planting, and such methods of culture as will hasten the 

 crop to maturity. (See Figs. 135 and 136.) 



The boll-weevil, as its name indicates, originally came 

 from Mexico, and in ten years' time it has spread over 

 all of central and eastern Texas and western Louisiana, 

 advancing at the rate of about 50 miles per year. It is 

 estimated that the annual loss to the farmers of Texas 

 occasioned by the boll-weevil is over $25,000,000. Far- 

 mers' Bulletin No. 189 of the United States Department 

 of Agriculture states that "there is not even a remote 



