38 



BULLETIN 564, U. S. DEPARTMENT OF AGRICULTURE. 



the weevils into the pan. A number of different types of these ma- 

 chines have been examined by the writers, and several of the most 

 promising were tested at Tallulah during the season of 1915. The 

 one of these which gave the best results during that season was 

 selected for more intensive studies during 1916. These studies were 

 of two types, (1) plat tests of the machine under field conditions, 

 and (2) comparative efficiency studies to determine the relative 

 weevil-collecting ability of this machine when compared with the 

 bag-and-hoop. 



PLAT TEST. 



The plat test was arranged in somewhat the same manner as the 

 Hecla test which has been described. The experimental principles 

 involved were much the same, and the same methods of arranging 

 the plats and buffers were followed. A very uniform strip of light 

 sandy soil was selected, and the plant growth over the entire experi- 

 mental area was rather unusually uniform. The light soil was 

 selected in order to secure plants of comparatively small size, since 

 the machine had shown a tendency to break larger plants rather 

 severely. Two plats were arranged, each 20 rows wide and 740 feet 

 in length. One of these was picked with the machine, while the 

 other was left unpicked as a check. 



The first picking was made on these plats on July 1. Originally 

 it was intended to start this picking somewhat earlier, but delay in 

 securing the machine postponed it until this date. However, as has 

 been mentioned, cotton of small size was secured, and the light and 

 late weevil emergence into this cut was such that only a slight infes- 

 tation was present on the 1st of July. Consequently, the condi- 

 tions more or less approximated those which would usually prevail 

 about two weeks earlier in a more severely infested cut of richer 

 soil. 



Table 33 shows the detailed results of the various pickings con- 

 ducted. 



Table 33. — Pickings with mechanical collector, Tallulah, La., 1916. 



Weevils 

 collected. 



Bolls collected. 



Clean. Infested. 



Squares collected. 



Clean. Infested. 



Time required. 



Hour. Minutes. 



Julyl 



July 11.... 

 July 24.... 

 July 31.... 



Aug. 7 



Aug. 15 



Aug. 21 



Aug. 21.... 



T t'll 



40 

 156 

 450 

 1,117 

 1,299 

 2,445 

 2,037 

 1,064 



115 



362 

 296 

 397 

 301 

 457 

 231 



103 



364 



21 



112 

 665 

 1,700 

 2,281 

 2,23S 

 1,363 

 2,037 

 1,079 



8, 608 



2,274 



11,475 



