FIBER CROPS 335 



as in maize and some other plants, it is sufficiently important to 

 be considered in attempting to maintain pure strains or in ma- 

 king improvements by selection. Pollen is mainly carried by 

 bees. Practical isolation may be secured by planting a quarter 

 or half a mile from other cotton, particularly if surrounded by 

 woods, although for accurate breeding work greater precaution 

 may be necessary. 



Where crossing is feared from undesirable types mixed with 

 the type it is desired to propagate, this may be prevented by 

 going through the fields as soon as the lower flowers appear 

 and removing all plants showing the undesirable characters. 

 Seed may then be selected from the upper bolls, which were fer- 

 tilized after the objectionable plants had been removed. 



426. Seed Selection. With cotton as with most other crops, 

 evidence is accumulating to show that the best results are ob- 

 tained by selecting where it is regularly grown rather than in 

 the change of seed. (C. A. 40, 41, 116, 277, 393) Probably half 

 the cotton seed planted is taken at random from the public gin. 

 Some of the more careful growers, however, send trusted em- 

 ployees through the field at the second, and if necessary to ob- 

 tain sufficient seed also at the third, picking who select the seed 

 cotton from the most productive plants of the type desired. The 

 first and fourth pickings are not generally considered so desira- 

 ble for seed. The seed cotton thus obtained is ginned separately. 

 By the use of such seed much has been accomplished in improv- 

 ing the general yield and quality of cotton. Cotton degenerates 

 easily and improves rapidly under careful selection. 



427. IMPROVEMENT OF COTTON. For those who wish to make more rapid 

 and definite progress in the improvement of cotton the United States Bureau 

 of Plant Industry recommends the following method which has been practised 

 successfully for several years by some growers of sea island cotton, the staple 

 having been increased from 1.75 to 2.5 inches by this method. 1 This method 

 requires four years of selection to secure seed for general planting. The fol- 

 lowing diagram shows the steps to be taken with each plant selected. 



iU. S. Dept. Agr. Yearbook 1898, pp. 358-62. 



