20 BULLETIN *742, U. S. DEPARTMENT OP AGRICULTURE. 



Department of Agriculture could furnish in guarding against the 

 deterioration of the seed used for planting. 



The growers in the Salt Hirer Valley having signified their desire 

 to cooperate with the department along these lines, experts were de- 

 tailed during the summer of 1913 to rogue x a limited acreage of wel'l- 

 grown Yuma cotton in order to obtain seed for increase during 1914 

 and for general planting in 1915. In 1914 the department's experts, 

 assisted bj^ representatives of the Salt River Valley Egyptian-Cotton 

 Growers' Association, rogued about 100 acres which had been 

 planted with seed from the fields which were rogued in 1913. Every 

 plant in this acreage was examined, and the unproductive and off- 

 type plants, amounting to about 1 per cent of the total, were removed. 

 The work was done early in July;, soon after blossoming began, in 

 order to take out the inferior plants before their pollen should con- 

 taminate those left in the field. Of the cotton groAvn from seed pro- 

 duced by fields which, were rogued in 1914, about 100 acres were 

 rogued during the summer of 1915, somewhat less than 1 per cent of 

 the plants being removed. 



In a 20-acre field of Yuma cotton which was rogued in 1916, 2 per 

 cent of the plants were removed as being " off type." 



A large part of the acreage planted to the Pima variety in 1916 

 and 50 acres of this variety in 1917 were rogued. The much greater 

 uniformity of the new type- was shown by the fact that whereas from 

 10 to 20 plants in every thousand of the Yuma variety had been re- 

 moved, only from 2 to 4 plants per thousand of the Pima variety 

 were taken out in roguing, although the latter variety was rogued 

 much more rigorously than the Yuma. 



The growers' association on its part has had the seed from the 

 rogued fields ginned under such conditions as to avoid mixing with 

 other seed, and also has had the seed sacked and tagged as it comes 

 from the gins, in order to prevent mixture while it is held in storage. 

 The rogued seed is placed hj the association in the hands of careful 

 farmers having good land sufficiently remote from other cotton to 

 1 prevent crossing. The fields planted under these conditions are in- 

 spected during the summer, and the. product of those which are 

 properly grown and are otherwise satisfactory is ginned separately, 

 in order to furnish seed for general planting the second year after 

 the roguing is done. Thus, the seed used for general planting in 

 1918 was derived from the fields which were rogued in 1916, and 

 that which will be used for general planting in 1919 has been derived 



from the fields rogued in 1917. It is believed that the seed from 



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1 The importance of early roguing cotton fields intended to furnish seed for planting 

 and the practicability of recognizing " off-type " plants in the early stages of their growth 

 have been pointed out by Mr. O. F. Cook. (Cotton selection on the farm by the characters 

 of the stalks, leaves, and bolls. U. S. Dept. Agr., Bur. riant Indus. Cir. 66, 23 p. 1910.) 



