CLIMATE 



219 



growth and hasten an undesirable premature ripening. After the 

 first part of August, however, when the plant has attained its full 

 vegetative growth, a lower and more varied temperature is desirable. 

 Cool nights at this period favor the production of a maximum crop, 

 for the lower temperature checks the vegetative growth and hastens 

 the maturation of the seeds and fiber. 



liegion Suited to Cotton. The cotton belt of the United States 

 is the area between 37 latitude and Gulf Coast and east of the west- 

 ern border of Texas. The heavy frosts of this section have generally 



FIG. 84. A field of upland cotton in September. 



ended by the middle of April, and if cotton is planted in time to 

 show above ground by the first of May there is little danger of it 

 being frost-killed. The frosts of autumn generally do not come 

 before the middle of October or the first of November, and the plant 

 has six to seven months of warm, frostless weather in which to pro- 

 duce its crop. The average mean temperature of the cotton belt, 

 from April to October, inclusive, ranges from 71 F. in the northern 

 area to 74 F. in the southern area. During the same period there 

 are, on the average, in each 100 days about 56 which are clear and 

 sunny, and 32 which are likely to produce rain. The climatic re- 



