﻿62 



BULLETIN 1374, U. S. DEPARTMENT OF AGEICULTUEE 



The records show increases in yield for all the treated plats, the 

 increase being greatest in the plats that received early treatment. 

 Records of blooming and bolls produced should be considered in 

 connection with the yields. Bloom counts were made weekly in each 



Elat, and boUs were counted just before the first pick and shortly 

 efore the second pick. The individual plat averages for both 

 blooms and boUs of the first crop are comparable among themselves 

 about as the yields of the first pick in the same plats. This holds 

 true, more or less, also with the second crop of blooms and bolls and 

 the yields of the second pick.. According to these records the increase 

 in yield of the treated plats can not be ascribed entirely to reduction 

 of the pink bollworm damage, but the poisoning evidently reduced 

 the infestation. 



Each boll count represents an average from 50 plants at each of 3 

 points per plat. The count of the first crop of bolls included only 

 boUs that were open just before the first picking. All of the first- 

 crop bolls were open at this time, but hardly any of those of the 

 second crop. Boll counts for the second crop were made several 

 weeks before the second picking and included both open and nearly 

 grown green bolls. No doubt the shedding of some of these green 

 bolls and the failure of others to open by the time of the second 

 picking, the smaller size of the bolls of the second crop, and the non- 

 pickable cotton practically all of which was of the second growth, all 

 contributed toward the much greater difi^erence that is found between 

 the yields of the first and the second picking than that found between 

 the records of total bolls of the first and of the second crop. 



Of three other series of poison tests conducted in 1922, two showed 

 increases in yield in treated plats. In the third there was a very 

 slight decrease. 



COMPAKATIVE EFFECTIVENESS OF DIFFEKENT POISONS 



Reduction in infestation was brought about by all three poisons 

 used in 1922. Sufficient experiments have not been made to deter- 

 mine whether one is more effective than the others. Because the 

 6-plat series treated with arsenite of zinc was left incomplete, a 

 comparison of the effectiveness of the three kinds of poison can be 

 based only on the results obtained in the two latest poisoned plats in 

 each of three 6-plat series on which different poisons were used. 

 This comparison of the poisons is shown in Table 50. 



Table 50. 



-Comparison of average infestation in plats treated with different kinds 

 of poison 



Plat No. 



Treatment 



Average number of worms per 

 boll per examination 



Calcium 

 arsenate 



Arsenite 

 of zinc 



Lead 

 arsenate 



1 and 6 



Check 



15.13 

 4.29 

 4.07 



15.13 

 4.30 

 4.17 



15.13 



4 



Aug. 9 to Sept. 7- . 



4.19 



5 



Aug. 22 to Sept. 26 



4.15 









'Average of checks, all series. 



